Wall Area Calculator (Wall, Ceiling and Floor Square Footage, with Doors, Windows, Perimeter and Volume)

Enter the room size (length × width) and the ceiling height. For openings such as doors and windows, enter the width, height and count on each row (leave rows you do not use blank).

Units

How to enter the room size

Room length (m)

Room width (m)

Ceiling height (m)

Unit for openings

Openings (doors, windows, closet doors and so on)

Row Width Height Count

Measure the inside dimensions (from wall surface to wall surface). A blank count is treated as 1.

Result and figure

Enter the room size, the ceiling height and the openings in the fields on the left and press "Calculate". The result and an unfolded view of the walls will appear here.

[ CLOSE ]

What you can do on this page
What is this calculation used for?
How to Use
Formulas and figures
Symbols and terms
- Symbols
- Terms
Good to know before you start
How to calculate it in Excel
How to calculate it in Google Sheets
How to calculate it in Python
How to write it in LaTeX and other math languages (copy and paste)
How to have ChatGPT do the calculation
DataChef Features
Related Features
NumberChef Calculators List

What you can do on this page

Enter the length, width and ceiling height of a room, and you get the floor area, ceiling area, wall area, perimeter and volume all at once
Enter up to 6 rows of openings such as doors and windows (width × height × count) to get the net wall area with the openings taken out
Room dimensions are in feet and openings in inches or feet. Switch "Units" above the calculator to Metric to work in meters
The result is drawn as an unfolded view of the four walls, so you can see which area was calculated
Use it to get the areas before you estimate wallpaper, paint, drywall or insulation. A plain-language explanation of the formulas and copy-and-paste formulas for Excel, Google Sheets and Python are all on this page

The room is treated as a rectangle (a box) with a flat ceiling. For an L-shaped room, split it into rectangles and add the results.

What is this calculation used for?

Estimating wallpaper

You estimate wallpaper from the net wall area. For example, a 12 × 10 ft room with an 8 ft ceiling, one door (32 × 80 in) and one window (36 × 48 in) has a gross wall area of 352 ft². Take away the 29.78 ft² of openings and 322.22 ft² is the area to paper.
The amount to buy is this area plus waste for pattern matching and cut-offs (the larger the pattern repeat, the more waste). You can also use this formula to check whether the square footage in a contractor's quote makes sense.

Painting walls and ceilings (DIY)

If you paint the walls and the ceiling together, the area to paint is "walls + ceiling": the net wall area plus the ceiling area. In the example above, that is 322.22 + 120 = 442.22 ft².
One gallon of paint typically covers about 350 to 400 ft² per coat, so two coats (884.44 ft²) take about \(884.44 \div 350 \approx 2.5\) gallons. Coverage differs by product and surface, so always check the can label or the maker's data sheet.

How much insulation, soundproofing or wall panels you need

When you put insulation board, soundproofing or acoustic panels on the walls, the material goes on the net wall area without the openings. For the room above, start from 322.22 ft² and divide by the coverage of one panel. With 4 × 8 ft (32 ft²) boards, that is \(322.22 \div 32 \approx 10.07\), so 11 boards.
If you also cover the ceiling, add the 120 ft² ceiling area. Windows usually get a different treatment (curtains or interior storm windows), so it is normal to think about them separately from the walls.

Using the volume to choose fans, air purifiers and HVAC

Ventilation and air conditioning are about how much air the room holds, which is the volume. The example room holds \(120 \times 8 = 960\) ft³.
For ventilation that replaces the air 0.5 times per hour, you need \(960 \times 0.5 \div 60 = 8\) CFM, which you can compare with a fan's rated airflow in CFM. For air purifiers, a common guideline (from AHAM) is a CADR of at least 2/3 of the floor area for rooms with 8 ft ceilings: \(120 \times 2/3 = 80\) CFM. With a higher ceiling there is more air, so choose a larger unit.

Estimating trim you buy by length, such as baseboard and crown molding

Baseboard along the floor and crown molding along the ceiling are bought by length, not area, and the room perimeter is the estimate. The example room has a 44 ft perimeter. Baseboard does not run across the door, so take away the 32 in (about 2.67 ft) door width to get about 41.33 ft.
Trim is sold in stock lengths, so divide by the length of one piece and round up (41.33 ÷ 16 ≈ 2.58, so 3 pieces of 16 ft), then add some extra for miter cuts and mistakes.

Estimating drywall sheets for walls and a ceiling

Drywall usually comes in 4 × 8 ft sheets (32 ft² each). For the example room, walls + ceiling is 442.22 ft², so \(442.22 \div 32 \approx 13.8\), or 14 sheets. Adding about 10% for cuts and waste gives about 16 sheets.
Many installers do not subtract small openings for drywall, because the cut-out pieces are rarely usable. Working it out from the areas before you order helps you avoid a second trip to the store.

Formulas and figures

Floor area and ceiling area

Figure

Standard notation (the usual math form)

\(S_f\) \(=\) \(L\) \(\times\) \(W\)

\(S_c\) \(=\) \(S_f\)

In words (symbols replaced with words)

③ \(S_f\): floor area \(=\) ① \(L\): room length \(\times\) ② \(W\): room width

④ \(S_c\): ceiling area \(=\) \(S_f\): floor area

The formula in words

① Take the \(L\): room length

② multiply it by the \(W\): room width

③ and you get the \(S_f\): floor area

④ and the \(S_c\): ceiling area is the same value as the floor area (for a room with a flat ceiling)

Quick example

The floor area and ceiling area of a 12 × 10 ft bedroom are

floor area \(S_f\) \(=\) length (12 ft) \(\times\) width (10 ft)

\(12 \times 10 = 120\,\mathrm{ft^2}\)

\(S_c = S_f = 120\,\mathrm{ft^2}\)

Key idea

The floor of the room is a rectangle, so the floor area is length × width. In an ordinary room with a flat (level) ceiling, the ceiling is the same shape as the floor lifted straight up, so the ceiling area equals the floor area. A sloped (vaulted) ceiling or exposed beams make the ceiling area larger than the floor area; in that case, measure the ceiling separately. Measure the inside dimensions, from wall surface to wall surface. If a length has extra inches, turn them into feet first (10 ft 6 in = 10.5 ft).

Room perimeter (total length of the walls)

Standard notation (the usual math form)

\(P\) \(=\) \(2\) \(\times\) \((\) \(L\) \(+\) \(W\) \()\)

In words (symbols replaced with words)

③ \(P\): perimeter \(=\) \(2\) \(\times\) \((\) ① \(L\): length \(+\) ② \(W\): width \()\)

The formula in words

① Add the \(L\): length

② and the \(W\): width and double it (there are two walls of each length)

③ and you get the \(P\): perimeter

Quick example

The perimeter of a 12 × 10 ft room is

perimeter \(P\) \(=\) \(2\) \(\times\) \((\) length (12 ft) \(+\) width (10 ft) \()\)

\(2 \times (12 + 10) = 2 \times 22 = 44\,\mathrm{ft}\)

Key idea

The perimeter is the distance all the way around the room: the widths of the four walls added together. In a rectangular room, opposite walls are the same length, so add the length and the width and double it. Besides the wall area, the perimeter is the starting point for estimating baseboard (the trim where the floor meets the wall) and crown molding (the trim where the ceiling meets the wall).

Gross wall area (the wall area before openings)

Figure

Standard notation (the usual math form)

\(S_w\) \(=\) \(P\) \(\times\) \(H\)

In words (symbols replaced with words)

③ \(S_w\): gross wall area \(=\) ① \(P\): perimeter \(\times\) ② \(H\): ceiling height

The formula in words

① Take the \(P\): perimeter

② multiply it by the \(H\): ceiling height

③ and you get the \(S_w\): gross wall area

Quick example

The gross wall area of a room with a 44 ft perimeter and an 8 ft ceiling is

gross wall area \(S_w\) \(=\) perimeter (44 ft) \(\times\) ceiling height (8 ft)

\(44 \times 8 = 352\,\mathrm{ft^2}\)

Key idea

If you cut the four walls apart and lay them out in a row, they make one big rectangle whose width is the perimeter and whose height is the ceiling height, as in the figure (an unfolded view). So instead of working out "width × height" for each of the four walls and adding them, you get the wall area in one step as perimeter × ceiling height. At this stage the doors and windows are still counted as wall, so it is called the gross wall area.

Total area of openings (doors and windows)

Standard notation (the usual math form)

\(A_o\) \(=\) \(\sum\) \((\) \(w_i\) \(\times\) \(h_i\) \(\times\) \(n_i\) \()\)

In words (symbols replaced with words)

⑤ \(A_o\): total area of openings \(=\) ④ \(\sum\) \((\) ① \(w_i\): opening width \(\times\) ② \(h_i\): opening height \(\times\) ③ \(n_i\): count of that size \()\)

The formula in words

① Take the \(w_i\): opening width

② multiply it by the \(h_i\): opening height to get the area of one opening

③ multiply by the \(n_i\): count of that size to get the total for that size

④ add this up for every row you entered (the symbol \(\sum\) means "add them all up")

⑤ and you get the \(A_o\): total area of openings

Quick example

For a room with one door (32 in wide × 80 in high) and one window (36 in wide × 48 in high), the total area of openings is

total openings \(A_o\) \(=\) door width (32 in) \(\times\) door height (80 in) \(\times\) count (1) \(+\) window width (36 in) \(\times\) window height (48 in) \(\times\) count (1)

\(32 \times 80 \times 1 \div 144 \approx 17.78\,\mathrm{ft^2}\)

\(36 \times 48 \times 1 \div 144 = 12\,\mathrm{ft^2}\)

\(17.78 + 12 = 29.78\,\mathrm{ft^2}\)

Key idea

Doors, windows, closet doors, sliding patio doors and other parts that get no wallpaper or paint are called openings. The subscript \(i\) is the row number ("row 1, row 2, …"). If there are two windows of the same size, enter 2 as the count \(n_i\) instead of using two rows. Door and window sizes are usually given in inches, so turn in² into ft² by dividing by 144 (1 ft² = 12 × 12 in²). When hanging wallpaper, small windows and vents are sometimes counted as wall instead of subtracted (the cut-off pieces often mean you save no material anyway). Decide which openings to subtract based on the material and the way it is installed.

Net wall area (the wall area minus openings)

Figure

Standard notation (the usual math form)

\(S_n\) \(=\) \(S_w\) \(-\) \(A_o\)

In words (symbols replaced with words)

③ \(S_n\): net wall area \(=\) ① \(S_w\): gross wall area \(-\) ② \(A_o\): total area of openings

The formula in words

① From the \(S_w\): gross wall area

② subtract the \(A_o\): total area of openings

③ and you get the \(S_n\): net wall area

Quick example

For a room with a gross wall area of 352 ft² and 29.78 ft² of openings, the net wall area is

net wall area \(S_n\) \(=\) gross wall area (352 ft²) \(-\) total openings (29.78 ft²)

\(352 - 29.78 = 322.22\,\mathrm{ft^2}\)

Key idea

"Net" means "what is left after taking out the extras", so \(S_n\) is the wall area that really needs wallpaper or paint. As in the figure, it is the unfolded wall rectangle with the doors and windows cut out. If you paint or paper both the walls and the ceiling, add the ceiling area \(S_c\) to get "walls + ceiling". When you buy materials, get a little more than this net area. Wallpaper needs extra for the pieces cut off to fit the ceiling height and for shifting to match the pattern, and paint increases with each coat (two coats, three coats). Those waste factors and coats are handled on the wallpaper, paint and flooring pages; this page stops at the net area after subtraction.

Room volume

Standard notation (the usual math form)

\(V\) \(=\) \(S_f\) \(\times\) \(H\)

In words (symbols replaced with words)

③ \(V\): room volume \(=\) ① \(S_f\): floor area \(\times\) ② \(H\): ceiling height

The formula in words

① Take the \(S_f\): floor area

② multiply it by the \(H\): ceiling height

③ and you get the \(V\): room volume

Quick example

The volume of a room with a floor area of 120 ft² and an 8 ft ceiling is

volume \(V\) \(=\) floor area (120 ft²) \(\times\) ceiling height (8 ft)

\(120 \times 8 = 960\,\mathrm{ft^3}\)

Key idea

The volume is the amount of air in the room when you treat it as a box, in cubic feet (ft³): length × width × height, or floor area × ceiling height. It is used to size exhaust fans and ventilation (fan airflow is rated in CFM, cubic feet per minute), to think about heating, cooling, humidifiers and air purifiers in terms of how much air the room holds, and to work out how much fogger or other product to use for the space.

For the walls of a room, find the gross wall area as perimeter (2 × (length + width)) × ceiling height, then subtract the total area of doors, windows and other openings to get the net wall area for estimating materials. The floor and ceiling areas are length × width, and the volume is floor area × ceiling height. The amounts of material with waste and coats (rolls, gallons, planks) are worked out on the wallpaper, paint and flooring pages.

Symbols and terms

Symbols

\(L\)	ell	The room length (ft), from "length". Measure the inside dimension (wall surface to wall surface).
\(W\)	double-u	The room width (ft), from "width". It does not matter which side you call the length and which the width.
\(H\)	aitch	The ceiling height (ft), from "height" - the height from the floor to the ceiling.
\(S_f\)	ess sub eff	The floor area (ft²). \(S\) is often said to come from "surface" or "square", and the subscript f stands for "floor". It is found with \(S_f = L \times W\).
\(S_c\)	ess sub cee	The ceiling area (ft²). The subscript c stands for "ceiling". For a flat ceiling it equals the floor area.
\(P\)	pee	The room perimeter (ft), from "perimeter". It is found with \(P = 2(L + W)\).
\(S_w\)	ess sub double-u	The gross wall area (ft²). The subscript w stands for "wall". It is the area of the four walls before openings are subtracted, found with \(S_w = P \times H\).
\(w_i\)	double-u sub i	The width of the opening in row \(i\), from "width". The subscript \(i\) is the row number of the input (row 1, row 2, …).
\(h_i\)	aitch sub i	The height of the opening in row \(i\), from "height".
\(n_i\)	en sub i	The count of openings in row \(i\), from "number". For two windows of the same size, it is 2.
\(A_o\)	ay sub oh	The total area of openings (ft²). \(A\) stands for "area" and the subscript o for "opening".
\(\sum\)	sigma	The Greek letter sigma (the Greek S), used as the first letter of "sum" to mean "add them all up". \(\sum (w_i \times h_i \times n_i)\) means "add up the area of every row".
\(S_n\)	ess sub en	The net wall area (ft²). The subscript n stands for "net". It is found with \(S_n = S_w - A_o\).
\(V\)	vee	The room volume (ft³), from "volume". It is found with \(V = S_f \times H\).

Terms

opening	Any part of the wall that is open, such as doors, windows, sliding patio doors, closet doors and doorways. They get no wallpaper or paint, so you subtract them from the wall area when you estimate materials.
perimeter	The distance all the way around a shape. For a room it is the total width of the four walls; for a rectangular room it is 2 × (length + width).
gross wall area	The total area of the four walls, counting doors and windows as wall. It is perimeter × ceiling height.
net wall area	The gross wall area minus the openings - the area that really needs wallpaper or paint. "Net" means what is left after the extras are taken out.
ceiling height	The height from the finished floor to the finished ceiling. 8 ft is standard in US homes, and 9 or 10 ft is common in newer homes.
inside dimension	The size measured from one wall surface to the other - the space you can actually use inside the room. Wallpaper, paint and flooring are estimated with these dimensions.
unfolded view	A drawing of a solid with its faces cut apart and laid flat (a net). Laying the four walls of a room in a row gives one rectangle whose width is the perimeter and whose height is the ceiling height, so you can see the wall area at a glance.
volume	The size of the space inside something. For a room it is floor area × ceiling height, in cubic feet (ft³). It is the basis for thinking about ventilation and heating or cooling.
drywall	Gypsum board used for the walls and ceilings of most US homes (also called sheetrock or wallboard). It is sold in sheets, most often 4 × 8 ft (32 ft²), so the number of sheets comes from the wall and ceiling area.
baseboard	The long, narrow trim board along the bottom of the wall where it meets the floor. It protects the bottom of the wall from dirt and bumps. The length you need is about "perimeter − door widths".
crown molding	The trim along the top of the wall where it meets the ceiling. The perimeter of the room is a good estimate of the length you need.
square footage	An area in square feet. The square footage in a US home listing is usually measured from the outside of the exterior walls (the ANSI Z765 standard for single-family homes), so it is larger than the sum of the inside room sizes. Use inside dimensions for wallpaper and paint.
sliding patio door	A large glass door that reaches the floor, used to go out to a patio, deck or yard. It is one of the largest openings, so always subtract it.
pattern matching	Hanging patterned wallpaper so that the pattern lines up from one strip to the next. The strips are cut to follow the pattern repeat, so there is more waste and you need more paper.
stock length	The fixed length in which trim and lumber are sold (for example 8, 12 or 16 ft). Divide the length you need by the stock length and round up to get the number of pieces to buy.

Good to know before you start

Here is what helps you use the calculation on this page with real understanding, not just by pressing the button.

Area and perimeter of a rectangle (Grade 3)	Knowing that the area of a rectangle is length × width Knowing that the perimeter of a rectangle is 2 × (length + width), because opposite sides are the same length
Volume of a rectangular prism (Grade 5)	Knowing that the volume of a box is length × width × height = base area × height Knowing the difference between a unit of volume, \(\text{ft}^3\) (cubic feet), and a unit of area, \(\text{ft}^2\) (square feet)
Nets of solids (Grade 6)	Being able to look at a net (the faces of a box laid out flat) and tell which face was where
Converting units of length and area (Grades 4–5)	Knowing that 1 ft = 12 in and 1 ft² = 144 in², so you can turn 6 in into 0.5 ft and in² into ft²
Multiplying and subtracting decimals (Grades 4–5)	Understanding what decimal calculations such as \(10.5 \times 12\) and \(352 - 29.78\) mean (a calculator can do the arithmetic)
Area of composite figures (Grades 3–6)	Knowing that you can find the area of a shape with holes by subtracting the small rectangles from the big one

How to calculate it in Excel

Copy the whole table below and paste it into cell A1 in Excel. It works as is.

Table to find the floor area and ceiling area

Room length (ft)	12
Room width (ft)	10
Floor area (ft²)	=B1*B2
Ceiling area (ft²)	=B3

Table to find the room perimeter

Room length (ft)	12
Room width (ft)	10
Perimeter (ft)	=2*(B1+B2)

Table to find the gross wall area

Perimeter (ft)	44
Ceiling height (ft)	8
Gross wall area (ft²)	=B1*B2

Table to find the total area of openings

Opening 1 width (in)	32
Opening 1 height (in)	80
Opening 1 count	1
Opening 2 width (in)	36
Opening 2 height (in)	48
Opening 2 count	1
Total area of openings (ft²)	=(B1B2B3+B4B5B6)/144

Table to find the net wall area

Gross wall area (ft²)	352
Total area of openings (ft²)	29.78
Net wall area (ft²)	=B1-B2

Table to find the room volume

Floor area (ft²)	120
Ceiling height (ft)	8
Volume (ft³)	=B1*B2

After pasting, the upper rows of column B are your inputs and the last row is calculated automatically.
The first table gives a floor area of 120 ft² (the ceiling area in B4 is also 120), the second a perimeter of 44 ft and the third a gross wall area of 352 ft².
The fourth table takes up to two sizes of openings in inches and divides by 144 to get ft², giving about 29.78 ft². For three or more sizes, add three more rows (width, height and count) and add "+B7*B8*B9" inside the parentheses.
The fifth table gives a net wall area of 322.22 ft² and the sixth a volume of 960 ft³.

How to calculate it in Google Sheets

Copy the whole table below and paste it into cell A1 in Google Sheets. It works as is.

Table to find the floor area and ceiling area

Room length (ft)	12
Room width (ft)	10
Floor area (ft²)	=B1*B2
Ceiling area (ft²)	=B3

Table to find the room perimeter

Room length (ft)	12
Room width (ft)	10
Perimeter (ft)	=2*(B1+B2)

Table to find the gross wall area

Perimeter (ft)	44
Ceiling height (ft)	8
Gross wall area (ft²)	=B1*B2

Table to find the total area of openings

Opening 1 width (in)	32
Opening 1 height (in)	80
Opening 1 count	1
Opening 2 width (in)	36
Opening 2 height (in)	48
Opening 2 count	1
Total area of openings (ft²)	=(B1B2B3+B4B5B6)/144

Table to find the net wall area

Gross wall area (ft²)	352
Total area of openings (ft²)	29.78
Net wall area (ft²)	=B1-B2

Table to find the room volume

Floor area (ft²)	120
Ceiling height (ft)	8
Volume (ft³)	=B1*B2

The same formulas as in Excel (just basic arithmetic) work as is. Copy the whole table, paste it into cell A1, and replace the numbers in column B with your own.

How to calculate it in Python

room_length_ft = 12      # room length (ft)
room_width_ft = 10       # room width (ft)
ceiling_height_ft = 8    # ceiling height (ft)
# openings as (width in, height in, count). Add rows for more sizes
openings = [
    (32, 80, 1),         # door
    (36, 48, 1),         # window
]

floor_area = room_length_ft * room_width_ft                   # floor area (ft2)
ceiling_area = floor_area                                     # ceiling area (flat ceiling)
perimeter = 2 * (room_length_ft + room_width_ft)              # perimeter (ft)
gross_wall_area = perimeter * ceiling_height_ft               # gross wall area (ft2)
opening_area = sum(w * h * n for (w, h, n) in openings) / 144  # total openings (in2 -> ft2)
net_wall_area = gross_wall_area - opening_area                # net wall area (ft2)
wall_and_ceiling = net_wall_area + ceiling_area               # walls + ceiling (ft2)
volume = floor_area * ceiling_height_ft                       # volume (ft3)

print(f"Floor area: {floor_area:.4g} ft²")
print(f"Ceiling area: {ceiling_area:.4g} ft²")
print(f"Perimeter: {perimeter:.4g} ft")
print(f"Gross wall area: {gross_wall_area:.4g} ft²")
print(f"Total openings: {opening_area:.4g} ft²")
print(f"Net wall area: {net_wall_area:.5g} ft²")
print(f"Walls + ceiling: {wall_and_ceiling:.5g} ft²")
print(f"Volume: {volume:.5g} ft³")

Runs with the standard library only. Add (width, height, count) sets to the openings list to handle any number of opening sizes. Replace the room size at the top with your own numbers and run it.

How to write it in LaTeX and other math languages (copy and paste)

Floor area and ceiling area

S_f = L × W,  S_c = S_f

S_f = L \times W,\quad S_c = S_f

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>S</mi><mi>f</mi></msub>
    <mo>=</mo>
    <mi>L</mi><mo>&#xD7;</mo><mi>W</mi>
    <mo>,</mo>
    <msub><mi>S</mi><mi>c</mi></msub>
    <mo>=</mo>
    <msub><mi>S</mi><mi>f</mi></msub>
  </mrow>
</math>

S_f = L xx W,  S_c = S_f

Sf = L*W; Sc = Sf

Sf := L*W;  Sc := Sf;

Sf = L*W; Sc = Sf;

S_f = L × W, S_c = S_f

Room perimeter (total length of the walls)

P = 2 × (L + W)

P = 2(L + W)

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mi>P</mi>
    <mo>=</mo>
    <mn>2</mn>
    <mo>&#x2062;</mo>
    <mrow><mo>(</mo><mi>L</mi><mo>+</mo><mi>W</mi><mo>)</mo></mrow>
  </mrow>
</math>

P = 2(L + W)

2*(L + W)

P := 2*(L + W);

P = 2*(L + W);

P = 2(L + W)

Gross wall area (the wall area before openings)

S_w = P × H

S_w = P \times H

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>S</mi><mi>w</mi></msub>
    <mo>=</mo>
    <mi>P</mi><mo>&#xD7;</mo><mi>H</mi>
  </mrow>
</math>

S_w = P xx H

Sw = P*H

Sw := P*H;

Sw = P*H;

S_w = P × H

Total area of openings (doors and windows)

A_o = Σ (wᵢ × hᵢ × nᵢ)

A_o = \sum_{i} \left( w_i \times h_i \times n_i \right)

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>A</mi><mi>o</mi></msub>
    <mo>=</mo>
    <munder><mo>&#x2211;</mo><mi>i</mi></munder>
    <mrow>
      <mo>(</mo>
      <msub><mi>w</mi><mi>i</mi></msub>
      <mo>&#xD7;</mo>
      <msub><mi>h</mi><mi>i</mi></msub>
      <mo>&#xD7;</mo>
      <msub><mi>n</mi><mi>i</mi></msub>
      <mo>)</mo>
    </mrow>
  </mrow>
</math>

A_o = sum_i (w_i xx h_i xx n_i)

Ao = Total[w*h*n]

Ao := add(w[i]*h[i]*n[i], i = 1 .. k);

Ao = sum(w .* h .* n);

A_o = ∑_i (w_i × h_i × n_i)

Net wall area (the wall area minus openings)

S_n = S_w − A_o

S_n = S_w - A_o

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msub><mi>S</mi><mi>n</mi></msub>
    <mo>=</mo>
    <msub><mi>S</mi><mi>w</mi></msub>
    <mo>&#x2212;</mo>
    <msub><mi>A</mi><mi>o</mi></msub>
  </mrow>
</math>

S_n = S_w - A_o

Sn = Sw - Ao

Sn := Sw - Ao;

Sn = Sw - Ao;

S_n = S_w − A_o

Room volume

V = S_f × H

V = S_f \times H

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mi>V</mi>
    <mo>=</mo>
    <msub><mi>S</mi><mi>f</mi></msub>
    <mo>&#xD7;</mo>
    <mi>H</mi>
  </mrow>
</math>

V = S_f xx H

V = Sf*H

V := Sf*H;

V = Sf*H;

V = S_f × H

How to have ChatGPT do the calculation

You are a quantity calculation assistant for interior work. Do the following calculation by actually running Python code, and base your answer only on the numbers from the execution result (do not answer by mental math or guessing).

A rectangular room is 12 ft long and 10 ft wide, with an 8 ft ceiling. The walls have one door (32 in wide × 80 in high) and one window (36 in wide × 48 in high).
Find each of the following:
1. The floor area and the ceiling area (ft²)
2. The room perimeter (ft)
3. The gross wall area (perimeter × ceiling height, ft²)
4. The total area of the openings (ft²)
5. The net wall area (gross wall area − openings, ft²) and the walls + ceiling area (ft²)
6. The room volume (ft³)

Show the formulas you used and the numbers from the execution result.

How to Use

1

Enter your numbers

Type the numbers you want to calculate with into the input fields
2

Calculate

Press the "Calculate" button
3

Check the result

The result appears on the spot. The same page also explains the idea behind the calculation and the formula