This square footage calculator multiplies length by width and reports the area in square feet, square yards, and square metres. Length and width can include extra inches, so a room that is 12 feet 6 inches by 10 feet does not have to be rewritten as 12.5. Twelve inches are one foot. Inches past 12 are still added, which is useful when a tape reading is 10 feet 18 inches and you would rather not do the carry yourself. A second rectangle, entered in decimal feet, is added for an L-shaped room. The sample is 12 feet 6 inches by 10 feet, with no second rectangle and no extra for ordering. The headline is 125.00 square feet, which is 13.89 square yards and 11.61 square metres.
The floor tile calculator already knows that a 10 by 12 foot floor is 120 square feet, and then it counts tiles. This page stops at the area. With a 10% extra allowance that same floor is 132.00 square feet, the area the tile page divides by the coverage of one tile. Paint is wall area in gallons. Concrete is a volume. Mulch and gravel are volumes at a depth. None of those headlines is a square-footage measurement of the floor you are standing on. Real-estate “finished square footage” under ANSI Z765 is a different set of rules about stairs, garages, and below-grade space. This form is the arithmetic of the rectangles you measure.
How to use this calculator
- Enter the length in feet and any extra inches. The sample length is 12 feet and 6 inches. Inches may be 0. They may also be more than 12. A negative inch is rejected.
- Enter the width the same way. The sample width is 10 feet and 0 inches. Both sides have to produce an area above zero. A length with a zero width is not a room.
- If the room is an L, enter the second rectangle’s length and width in feet. Leave both at 0 for a single rectangle. Entering only one side of the second rectangle is rejected, so a forgotten width does not silently disappear.
- Type an extra-to-order percentage if you are buying carpet, vinyl, or underlayment, or leave 0. Press Calculate. The headline is the measured square feet, before that extra. The ordering line is underneath.
How square feet, square yards, and square metres are calculated
Each side in feet is the foot count plus the inches divided by 12. The sample length is 12 + 6/12, which is 12.5 feet. Times 10 feet, the area is 125 square feet. One square yard is 9 square feet, so 125 / 9 is 13.888…, displayed as 13.89 square yards. One international foot is 0.3048 metres, so one square foot is 0.3048 × 0.3048, or 0.09290304 square metres. Times 125, that is 11.61288 square metres, displayed as 11.61. The length converter on this site turns metres into feet. It does not multiply two sides, and it does not use this exact square-metre factor. Its foot factor is the rounded 3.28084 used for a one-way length conversion.
An L is two rectangles that do not overlap. A 20 by 15 foot main room is 300 square feet. An 8 by 6 foot wing, measured as the part that sticks out and not as a second copy of the main room, is 48 square feet. The total is 348.00 square feet, 38.67 square yards, and 32.33 square metres. If you measure the bounding box, 20 by 21, you include the empty corner. That box is 420 square feet and is the wrong area. If you measure the wing as 20 by 6 because the tape ran the full length of the house, you have counted a strip of the main room twice. The second rectangle is only the additional piece. Draw a line where the two rectangles meet and measure each one up to that line.
Inches that are not a tidy half foot still multiply. A room 8 feet 3 inches by 10 feet 4 inches is 8.25 feet by 10.333… feet. The product is 85.25 square feet, 9.47 square yards, and 7.92 square metres. Eight and a quarter times ten and a third is exact in ordinary arithmetic: 8.25 × 31/3 = 85.25. The display rounds the square yards and the square metres. It does not round the square feet away from 85.25. Eighteen extra inches on a 10 foot side are 1.5 feet, so a 10 foot by 10 foot room with 18 inches added to the length is 11.5 × 10, or 115.00 square feet. You do not have to convert 18 inches to 1 foot 6 inches before you type.
The extra-to-order field does not change the headline. A 10 by 12 foot floor is 120.00 square feet, 13.33 square yards, and 11.15 square metres. Ten percent extra makes the ordering line 132.00 square feet, 14.67 square yards, and 12.26 square metres. The tile page uses that 132 square feet, with a 1/8 inch grout joint, to reach 129.29 tiles before rounding up to 130. This page will not produce the 130. Carpet sold by the square yard is the 13.33 line, or 14.67 if you are ordering the extra. A 10% allowance is not a measurement of the room. It is waste, pattern match, and the piece you would rather have left over than go back for.
Formula
Length in feet = feet + inches / 12 Width in feet = feet + inches / 12 First rectangle = length × width Second rectangle = its length × its width, or 0 when both sides are 0 Square feet = first rectangle + second rectangle Square yards = square feet / 9 Square metres = square feet × 0.3048 × 0.3048 Ordering area = square feet × (1 + extra percent / 100) The headline is the measured square feet, before the extra.
The international foot of 0.3048 metres is exact by agreement, so 0.09290304 square metres per square foot is exact before display rounding. An older US survey foot is not used. A result in square metres that came from a rounded 0.093 factor will disagree in the second decimal on a large floor. This page multiplies by 0.3048 twice and then rounds the displayed square metres to two decimals. At 125 square feet the unrounded product is 11.61288, which displays as 11.61.
Square inches are square feet times 144, and acres are square feet divided by 43,560. Neither is the headline, because a room is not usually bought in those units. A 125 square foot room is 18,000 square inches and about 0.0029 acres. A lot measured in acres should be entered as feet only after you have converted, or the number will look like a room. The form accepts a large foot count. It does not know whether you measured a bedroom or a paddock.
Worked square-footage examples
12 feet 6 inches by 10 feet
The length is 12.5 feet and the width is 10 feet. The headline is 125.00 sq ft. Square yards are 13.89. Square metres are 11.61. The second rectangle line says it was not used. The ordering line at 0% extra repeats 125.00 square feet. Six inches are half a foot, so this is the same area as typing 12.5 in the foot field and 0 inches. The inch field exists so the half does not have to be converted first.
Add 10% extra and the headline stays 125.00 sq ft. The ordering line becomes 137.50 square feet. That extra is for a cut or a pattern. It is not a larger room. The tile page’s waste field works the same way on area, and then it goes on to count pieces. This page stops at the area.
The 10 by 12 floor the tile page starts from
Length 10 feet, width 12 feet, no extra inches, and no second rectangle: 120.00 square feet, 13.33 square yards, and 11.15 square metres. With 10% extra the ordering area is 132.00 square feet, 14.67 square yards, and 12.26 square metres. The floor tile calculator’s worked example takes that 132 square feet, divides by 1.0209 square feet of tile-plus-joint, and rounds 129.29 tiles up to 130. If you only needed the area, you are done on this page. If you need the box count, the tile page is the one that knows the carton.
A square yard of carpet for the measured floor is the 13.33 line, not the 14.67 line, unless you meant to buy the waste. Some carpet remnants are sold by the square foot. The headline is that unit. The conversion does not change because the material changed. Vinyl, hardwood, and carpet use the same floor area and then apply their own waste, which is why the extra percentage is a field you set rather than a hidden 10%.
An L-shape, and a room that is not a whole number of feet
A 20 by 15 foot rectangle plus an 8 by 6 foot wing is 300.00 plus 48.00, so the headline is 348.00 sq ft. Square yards are 38.67 and square metres are 32.33. The wing is the protruding piece only. Measuring 20 by 21 as if the L filled its bounding box would report 420.00 square feet and would order too much material. Measuring the wing as 20 by 6, the full run of the house, would add a 120 square foot strip that is already inside the 20 by 15.
A room 8 feet 3 inches by 10 feet 4 inches is 85.25 sq ft, 9.47 square yards, and 7.92 square metres. Three inches are 0.25 feet and four inches are one-third of a foot. The product is exact at two decimals. A 10 foot square with 18 extra inches on one side is 115.00 sq ft, because 18 inches are 1.5 feet and the side is 11.5 feet. Both readings are accepted. You do not have to borrow twelve inches into the foot field before the form will multiply.
Square feet for rooms measured in feet and inches
| Measurement | Square feet | Square yards | Square metres |
|---|---|---|---|
| 12 ft 6 in × 10 ft | 125.00 | 13.89 | 11.61 |
| 10 ft × 12 ft | 120.00 | 13.33 | 11.15 |
| 10 ft × 12 ft, plus 10% extra | 132.00 ordered | 14.67 ordered | 12.26 ordered |
| 20 ft × 15 ft plus 8 ft × 6 ft | 348.00 | 38.67 | 32.33 |
| 8 ft 3 in × 10 ft 4 in | 85.25 | 9.47 | 7.92 |
| 10 ft × 10 ft, plus 18 in on the length | 115.00 | 12.78 | 10.68 |
What this square-footage measurement leaves out
Finished square footage for a listing follows measurement standards this form does not apply. ANSI Z765 distinguishes above-grade and below-grade area, excludes open areas to the floor below, and has rules for stairs and ceiling height. A basement, a garage, and a screened porch can be area you can measure and still not be “finished square footage” in a listing. Type the rectangles you mean, and do not read the headline as an appraisal.
The second rectangle is added in full. There is no overlap subtraction. If your two measurements share a strip, the total is high by that strip. A T-shape or a U-shape needs the same discipline: split the floor into rectangles that meet at edges and do not cover one another, then put only one of them in the second pair of fields. A third rectangle has to be added by you to the headline. The form has two. Slopes, bay windows, and circles are not a length times a width. A circular alcove is a separate bit of geometry.
The extra percentage increases the ordering line only. It does not know the width of a carpet roll, the direction of a plank, or a tile that needs a grout joint. The tile page adds the joint before it counts pieces. This page, given the same 10 by 12 floor and 10% extra, stops at 132.00 square feet. Paint coverage is wall area, which includes height and excludes openings. A floor area is the wrong input for gallons. Concrete, mulch, and gravel need a depth. Square feet times a depth in inches, divided by 12, is cubic feet, and this form does not ask for the depth.
Units are the international foot and the square metre that follows from it. A metric room should be converted to feet first, on the length converter, or measured again in feet. That converter’s displayed foot factor is rounded, so a room near a rounding boundary can pick up a small difference if you convert each wall and multiply here. Measuring in feet on site avoids that. The result is an area, not a price. A cost per square foot is a multiplication you do after you trust the area.
Frequently asked questions
How many square feet is a room that is 12 feet 6 inches by 10 feet?
125.00 square feet. The 6 inches are half a foot, so the length is 12.5 and 12.5 times 10 is 125. That is 13.89 square yards and 11.61 square metres. The square-metre factor is 0.09290304, from a foot of 0.3048 metres. The headline does not include an ordering allowance unless you type one, and a 10% allowance would change the ordering line to 137.50 square feet without changing the 125.00 headline.
How do I calculate the square footage of an L-shaped room without counting the corner twice?
Split the L into two rectangles that share an edge and do not overlap, then enter the second rectangle in the extra length and width. A 20 by 15 foot piece plus an 8 by 6 foot piece is 348.00 square feet, 38.67 square yards, and 32.33 square metres. The bounding box, 20 by 21, is 420 square feet and includes empty space. A wing measured along the full 20 foot wall counts part of the main room a second time.
What is 120 square feet in square yards and square metres?
A 10 by 12 foot floor is 120.00 square feet, 13.33 square yards, and 11.15 square metres. Square yards are the area divided by 9. Square metres use 0.09290304 square metres per square foot. With 10% extra the ordering area is 132.00 square feet. The floor tile page starts from that same 120, and from the 132 after waste, and then counts tiles. This page does not.
Can I type 18 inches instead of converting them to a foot and a half?
Yes. Inches are divided by 12 and added to the foot count, including when they exceed 12. A 10 foot side plus 18 inches is 11.5 feet. A 10 foot by 10 foot room with that extra on the length is 115.00 square feet, 12.78 square yards, and 10.68 square metres. The inch fields accept 0 through 120. A negative inch is rejected. You can still convert first and type 11.5 feet with 0 inches. The area is the same.
Does this square footage calculator follow real-estate finished-area rules?
No. It multiplies the rectangles you enter. Listing standards such as ANSI Z765 decide which spaces count as finished square footage, how stairs are treated, and how below-grade area is reported. A garage or a porch can have an area on this page and still be excluded from a listing total. Measure the floor you mean, and treat the headline as that measurement rather than as an appraisal.
Related ClearCalc pages
- Floor tile calculator The 10 by 12 foot floor is 120 square feet here and 130 tiles there, once a 1/8 inch joint and 10% waste are included.
- Room paint calculator Gallons from wall height, openings, and coats. A floor area is not a wall area, and this page has no ceiling height.
- Concrete slab calculator Cubic yards and bags from a thickness in inches. Square feet are only the start of that volume.
- Length converter from meters Metres to feet for one length. It does not multiply two sides, and its displayed foot factor is a rounded 3.28084 rather than this page’s exact 0.3048 metre foot.