Convert ft² to in² square feet ↔ square inches Free Online Secure
Type a value in square feet and read it in square inches at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
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Common values — Convert ft² to in² (square feet ↔ square inches)
| ft² | in² |
|---|---|
| 1 | 144 |
| 2 | 288 |
| 3 | 432 |
| 5 | 720 |
| 10 | 1440 |
| 20 | 2880 |
| 50 | 7200 |
| 100 | 14400 |
Where these units come from
Square units need no definition of their own: a square metre is a metre by a metre, and everything follows from the length. The land measures are older and stranger. The acre began as the land a yoke of oxen could plough in a day, which is why it was long and thin rather than square — one chain by one furlong, 4840 square yards. The hectare and the are came out of the French Revolution, when land had to be measured in something decimal; neither belongs to the International System, but both were kept for land because a hectare is a comfortable size to picture and a square metre is not. Since the 1959 agreement on the yard, the acre is exactly 4046.8564224 square metres, so the conversions on this page are exact rather than approximate.
Where you meet them
Square metres price flats, size carpets and decide how much paint a wall needs; square feet do the same work in the United States and in much of the property market worldwide. Hectares belong to farmland, forests and planning permissions; acres to land deeds in the English-speaking world. Square kilometres and square miles are for countries, lakes and fires. Square centimetres and square millimetres live in workshops, on datasheets and anywhere a cross-section matters.
Questions people ask
How do I think about square feet?
A square foot is 0.09290304 square metres exactly, so a square metre is about 10.76 square feet. In the United States and in British property listings, floor space is given in square feet: a 100 square metre flat is a little under 1,100 square feet. Divide by ten and a bit to go from feet to metres.
How many square millimetres is a square inch?
Exactly 645.16, or 6.4516 square centimetres. The figure follows from the inch being exactly 25.4 millimetres: squaring 25.4 gives 645.16. Square inches turn up in the pressure unit psi, in the sizes of screens and prints, and in small component specifications.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
One hundred and forty four square inches in every square foot
A square foot is a square twelve inches on a side, and since there are twelve rows of twelve square inches in it, the answer to the question how many is 144. To convert ft² to in² you multiply by 144, so 2 ft² is 288 in² and 0.5 ft² is 72 in². The number is easy to remember because 144 is a dozen dozen, a gross, but it is also easy to confuse with the linear factor of 12. That mistake is the most common one, and it makes the answer twelve times too small. This page multiplies as you type, and the text below shows where the conversion matters, from floor tiles to wind loads.
You will find the rule with worked examples, short profiles of the two units, a comparison, a long tour of real situations, and a list of the typical mistakes. The calculation runs in your browser and nothing you type is sent anywhere.
How to convert ft² to in²: multiply by 144
The rule
One square foot equals exactly 144 square inches. To convert ft² to in², multiply the number of square feet by 144. So 3 ft² is 432 in², 10 ft² is 1,440 in², 25 ft² is 3,600 in² and a thousand square feet are 144,000 in². Going the other way, divide square inches by 144.
Worked examples
A window of 15 ft² is 2,160 in². A door of 21 ft² is 3,024 in². A sheet of plywood, 4 by 8 feet, is 32 ft² or 4,608 in². For a quick estimate, multiply by 100 and add 44 per cent: 10 ft² gives 1,000 plus 440, which is 1,440, exactly right in this case.
A dozen dozen
The factor 144 is 12 times 12. In a square foot there are 12 strips of 12 inches. A way to see it is to imagine a tile 12 inches square on the floor, divided with a grid of one inch squares: you will count 12 columns and 12 rows.
A quick check
The square inch is the small unit, so the number must grow a lot. If your “convert ft² to in²” calculation gave you a number only 12 times bigger than the one you started with, you used the linear factor.
The square foot
12 by 12 inches
The square foot is the area of a square with sides of one foot, which equals 0.092903 square metres. It is the main unit for floor area in homes, shops and offices in the United States, and in construction in several other countries. Listings give the size of a house in ft², and rent is quoted per square foot per year.
Where it appears
Flooring, roofing, insulation, drywall and paint coverage all use square feet. A bag of tile adhesive may cover 60 ft², a gallon of paint 350 to 400.
The square inch
One inch by one inch
The square inch is 6.4516 square centimetres. It measures small surfaces: electronic parts, picture frames, cutting boards and, in pressure, the area on which pounds of force push. A tyre pressure of 32 psi means 32 pounds on each square inch.
Where it appears
Product labels in North America, hobby crafts, small appliance specifications and engineering drawings use square inches.
Square foot and square inch compared
A square foot is 144 times a square inch. The two units are used for different sizes of things: floors, walls and roofs in square feet, small parts in square inches. When both appear in the same document, such as a building code, converting between them is routine.
A common pitfall is the pair of pressure units: pounds per square inch, psi, and pounds per square foot, psf. The latter is used in building loads, and 1 psi equals 144 psf.
Where the conversion appears
Building loads
Building codes give floor loads in pounds per square foot. A residential floor must carry 40 psf, which is 0.278 psi. A roof designed for a snow load of 30 psf carries 30,000 pounds on 1,000 ft². Knowing that 1 psf is 1/144 psi helps when a manufacturer lists loads in psi.
Panels and sheets
A sheet of drywall of 4 by 8 feet is 32 ft², 4,608 in². A solar panel of 65 by 39 inches is 2,535 in², 17.6 ft². Both units appear on the datasheet in the same page, and a “convert ft² to in²” calculation puts them on the same scale.
Television and artwork
A 55 inch television has a screen area of about 1,290 in², 9 ft². A framed picture of 24 by 36 inches is 864 in², 6 ft². Decorators and retailers mix feet and inches daily, and the conversion tells you whether a piece fits the wall.
Psi versus psf
One pound per square inch is 144 pounds per square foot. A tyre at 35 psi presses on the road with 5,040 psf in the contact patch. A wind pressure of 20 psf is only 0.139 psi. Engineers use psf for loads on large surfaces and psi for fluids and small parts, and the factor 144 links the two.
Quilts and fabric
A bed quilt of 90 by 108 inches is 9,720 in², 67.5 ft². A baby quilt of 36 by 36 inches is 1,296 in², 9 ft². Fabric shops sell by the yard, but quilters plan in square inches for each block, such as 6 by 6 inches, 36 in². A large quilt uses hundreds of such blocks.
Roofing flashing and shingles
A roofing shingle of 12 by 36 inches covers 432 in², 3 ft². Contractors speak of a square, 100 ft² of roof, which equals 14,400 in² and about 33 shingles. Flashing around a chimney of 24 by 36 inches takes 864 in² of metal, 6 ft².
Door and window openings
A standard door of 36 by 80 inches is 2,880 in², 20 ft². A window of 36 by 60 inches is 2,160 in², 15 ft². Building codes require a certain percentage of floor area as window area, often 8 to 10 per cent, so a room of 150 ft² needs at least 12 ft² of windows, 1,728 in².
Sheet metal and plywood
A sheet of plywood 4 by 8 feet is 32 ft² or 4,608 in². A sheet of galvanised steel of 3 by 10 feet is 30 ft², 4,320 in². Suppliers sell by the sheet but price by the square foot, and a carpenter who cuts a piece of 18 by 24 inches, 432 in², uses 3 ft² of it.
Rounding
The factor 144 is exact, so nothing needs to be rounded until the end. For floor planning, round to the nearest square inch for small areas, and to the nearest ten for large ones. A result of 1,440 in² is exact for 10 ft².
Spreadsheet use
Put square feet in column A and write =A2*144 in column B. For the reverse, use =B2/144. A third column with =A2*0.092903 gives square metres. Format as whole numbers for square inches, and with two decimals for square feet.
Teaching the idea
On the floor, tape a square one foot on a side, then divide it with string into one inch squares. Students count 12 by 12, 144. They can also measure a tile or a book cover in inches and convert to square feet by dividing by 144, which makes the idea concrete.
Why 144 is called a gross
A gross is a dozen dozens, 144, an old merchants' count for pencils, buttons and pens. By chance, the number of square inches in a square foot is also a gross. Using a gross to remember 144 is a trick that helps many people, and it is a nice link between commerce and geometry.
Copper sheet and roofing metal
Copper sheet is sold by weight per square foot. A sheet of 16 ounce copper weighs one pound per ft², that is 0.0069 pounds per in². A roof of 500 ft² uses 500 pounds of copper, and a flashing piece of 36 in² weighs 0.25 pounds. The unit conversion links price lists with cutting plans.
Tile sizes
A tile of 12 by 12 inches is exactly one square foot, 144 in². A 6 by 6 inch tile is 36 in², 0.25 ft², so four make a square foot. A 24 by 24 inch tile is 576 in², 4 ft². Tile shops price per square foot, and a “convert ft² to in²” calculation shows how many tiles a room needs.
Wind load on a wall
A wind of 100 mph exerts about 25 psf on a flat wall. A wall of 10 by 8 feet, 80 ft², takes a force of 2,000 pounds. In psi the same pressure is 0.17, and over a window of 15 ft², 2,160 in², the force is 375 pounds. Designers of shutters and glass work with both figures.
Craft vinyl and adhesive paper
A roll of adhesive vinyl of 12 inches by 10 feet covers 10 ft², 1,440 in². A decal of 6 by 8 inches takes 48 in², so a roll provides 30 decals before waste. Crafters buy by the roll, plan in inches, and need conversions between the two.
Cabinets, shelves and closets
A kitchen wall cabinet of 30 by 12 inches has a front of 360 in², 2.5 ft². A closet shelf of 24 by 72 inches is 1,728 in², exactly 12 ft². Cabinet makers list door sizes in inches and finishing costs per square foot, so a “convert ft² to in²” calculation is needed whenever a quotation lists both. If you plan to paint a set of ten doors of 360 in² each, the total is 3,600 in², 25 ft², and you can compare it with the coverage on the can.
Posters, signs and banners
A poster of 24 by 36 inches has 864 in², 6 ft². A yard sign of 18 by 24 inches is 432 in², 3 ft². A banner of 3 by 10 feet is 30 ft², 4,320 in². Sign printers charge per square foot, but design files are in inches, so the printer's order form and the designer's drawing speak different units unless somebody does a “convert ft² to in²” calculation.
Garden beds and paving stones
A paving stone of 16 by 16 inches covers 256 in², 1.78 ft². A patio of 10 by 12 feet, 120 ft², needs 68 such stones. A raised bed of 4 by 8 feet is 32 ft², 4,608 in². Landscape suppliers sell stones by the piece and soil by the cubic foot, while the plan is in square feet, so the conversion appears on almost every garden project.
Checking an answer by eye
Picture a square foot as a large floor tile, and a square inch as a postage stamp. A tile holds 144 stamps, three quarters of the way to 200. If you convert 3 ft² and get 36, you can see at once that something is wrong, since three tiles must hold far more than a few dozen stamps. Visual checks like this catch most errors before any arithmetic is repeated, and a “convert ft² to in²” calculation that passes the check is usually right.
Snow load on a roof
A snow load of 40 psf is common in northern states. A roof of 1,500 ft² must therefore carry 60,000 pounds, 30 tons. In psi, the pressure is 0.28. Local codes give the value in psf, but material data sheets for roof panels may give strength in psi, so converting is part of design.
Table and desk surfaces
A table of 30 by 60 inches has 1,800 in², 12.5 ft². A desk of 24 by 48 inches has 1,152 in², 8 ft². Furniture makers list top surfaces in square inches, while store catalogues may quote square feet, so comparing two tables of different sizes may need a quick convert ft² to in².
Pool tables and ping pong
The playing surface of an eight foot pool table is 44 by 88 inches, 3,872 in², 26.9 ft². A table tennis table is 9 by 5 feet, 45 ft², 6,480 in². Owners who plan a games room compare the table area with the room size, usually in square feet.
Queen size and king size beds
A queen mattress of 60 by 80 inches is 4,800 in², 33.3 ft². A king of 76 by 80 inches is 6,080 in², 42.2 ft². Bedding manufacturers list in inches, while room planners talk about square feet. A king bed takes about a quarter more floor area than a queen.
Kitchen counters
A kitchen worktop 25.5 inches deep and 96 inches long has 2,448 in², 17 ft². Granite suppliers charge by the square foot, but cut by the inch, so the conversion appears on every quotation. A hole for the sink, 30 by 18 inches, 540 in², removes 3.75 ft² from the total.
Heat flux and insulation
Heat loss through a wall is expressed in BTU per hour per square foot. A wall of 120 ft² with a loss of 3 BTU per ft² per hour loses 360 BTU per hour. Smaller surfaces, such as a window frame of 300 in², 2.08 ft², are treated similarly. Energy calculations often mix both units.
Pizza and food
An 18 inch pizza has an area of 254 in², 1.77 ft². A 12 inch pizza has 113 in², 0.79 ft². A restaurant that prices by area finds that the bigger pizza gives 2.25 times as much food for a price only 1.5 times higher. Most diners do the arithmetic in square inches.
More values for convert ft² to in²
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 ft² = 14.4 in²
- 0.5 ft² = 72 in²
- 3 ft² = 432 in²
- 4 ft² = 576 in²
- 7 ft² = 1,008 in²
- 15 ft² = 2,160 in²
- 20 ft² = 2,880 in²
- 75 ft² = 10,800 in²
- 200 ft² = 28,800 in²
- 500 ft² = 72,000 in²
- 2,000 ft² = 288,000 in²
- 10,000 ft² = 1,440,000 in²
Mistakes when you convert ft² to in²
Using 12 instead of 144
That is the linear factor. For area, multiply by 144.
Mixing psi and psf
One psi is 144 psf. Mistaking one for the other means an error of two orders of magnitude.
Dividing instead of multiplying
The square inch is smaller, so the number grows. If 5 ft² became 0.035, you divided.
Quick answers
How many square inches in a square foot?
144.
How do I convert ft² to in²?
Multiply by 144.
What is 2.5 ft² in square inches?
360 in².
How many ft² in 1,000 in²?
6.94 ft².
Does my number leave my device?
No. The calculation runs in your browser.
Related pages and a last word
If you work with areas, these conversions are close at hand: Convert ft² to acres, Convert ft² to m², Convert mm² to in², Convert cm² to in², Convert in² to mm², Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C. The reverse of this page is Convert in² to ft².
In short, to convert ft² to in² multiply by 144, remember that the factor is the square of 12, and keep the digits your measurement supports. Your number stays on your device: nothing is uploaded and no account is needed.