Square Footage Calculator
A 12 by 10 rectangle, a 12 by 6 triangle, and a 10 by 8 L with a 4 by 4 cutout add to 220.00 square feet.
Last updated . Each shape has its own unit and its own add or subtract switch. Nothing here has a depth.
Add a rectangle, a triangle, a circle, or an L-shape. Subtract any of them from the net.
Volume from a depth: cubic yard calculator. Several flooring rooms: flooring calculator.
Square footage
Each shape uses one unit. An L-shape is the overall rectangle minus the cutout. A cutout larger than the overall rectangle counts as zero. Subtract removes that shape from the net.
Results
How the shapes are added
Rectangle area is length × width, 12 × 10 = 120.00 ft². Triangle area is base × height ÷ 2, 12 × 6 ÷ 2 = 36.00 ft². An L-shape is the overall rectangle minus the cutout, 10 × 8 − 4 × 4 = 64.00 ft². The net is 220.00 ft² · 20.44 m². A circle is π × radius². A 10 ft diameter is 78.54 ft².
Subtract flips that shape’s sign. A cutout longer or wider than the L counts as zero rather than a negative room. The result is an area. It does not apply a depth, a waste percent, or a price.
The opening three shapes
| Shape | Rule | Area |
|---|---|---|
| A, rectangle 12 × 10 | length × width | 120.00 ft² · 11.15 m² |
| B, triangle 12 × 6 | base × height ÷ 2 | 36.00 ft² · 3.34 m² |
| C, L 10 × 8 minus 4 × 4 | overall − cutout | 64.00 ft² · 5.95 m² |
| Net, all added | A + B + C | 220.00 ft² · 20.44 m² |
Worked example
Leave A as a 12 by 10 rectangle, B as a triangle 12 by 6, and C as an L, 10 by 8 with a 4 by 4 cutout. Leave every switch on Add. Net reads 220.00 ft² · 20.44 m².
Square footage questions
What is the square footage of the three default shapes?
Shape A stays a 12 by 10 rectangle. Shape B stays a triangle with base 12 and height 6. Shape C stays an L, 10 by 8 overall with a 4 by 4 cutout. All three stay on Add. Shape A reads 120.00 ft² · 11.15 m². Shape B reads 36.00 ft² · 3.34 m². Shape C reads 64.00 ft² · 5.95 m². Net reads 220.00 ft² · 20.44 m².
How is the L-shape calculated?
Overall 10 × 8 is 80. The cutout 4 × 4 is 16. Shape C is 80 − 16 = 64.00 ft² · 5.95 m². The cutout has to sit inside the overall rectangle. This page does not guess which corner the notch occupies. It only subtracts the area.
What if shape C is a circle?
Set shape C to Circle and leave the diameter at 10 ft. Shape C reads 78.54 ft² · 7.30 m². Shape A stays 120.00 ft² · 11.15 m² and shape B stays 36.00 ft² · 3.34 m². Net reads 234.54 ft² · 21.79 m². The circle is π × 5².
How do I subtract a shape?
Set shape C back to L-shape and set shape B to Subtract. Shape B reads − 36.00 ft² · 3.34 m². Net reads 148.00 ft² · 13.75 m². That is 120.00 + 64.00 − 36.00. The minus sign is on shape B only.
What if the L cutout is too big?
Set shape B back to Add. On shape C, set the cutout length to 12. The overall length is still 10, so the cutout does not fit. Shape C reads 0.00 ft² · 0.00 m². Net reads 156.00 ft² · 14.49 m². The note says a cutout is larger than its L-shape, so that shape counts as 0.
Can I enter shape A in meters?
Set the cutout length back to 4. Set shape A’s unit to m, length to 3.6576, and width to 3.048. Shape A still reads 120.00 ft² · 11.15 m². Net still reads 220.00 ft² · 20.44 m². Those meter values are 12 ft and 10 ft. Shapes B and C can stay in feet.
Does this turn square feet into cubic yards?
No. Net on the opening example is 220.00 square feet, an area. A depth, a swell factor, and truck loads are the excavation calculator. Cubic yards from length, width, and depth are the cubic yard calculator. This page only adds and subtracts flat shapes.