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Choose a shape, then enter its measurements.
Shape
Measurements
Square Footage Calculator
Calculate one room or combine several spaces, shapes, and measurement units in one project. Add an optional allowance and material price when you need a purchase estimate.
🌎 Region
Choose the country for starting measurement and currency labels. Switching regions resets the current project; it does not convert prices or fetch local rates.
📐 Areas & spaces
Break an irregular room into simple shapes and add each piece separately. Every area can use its own unit.
1 / 50 areas
✂️ Extra allowance
Add extra area for cuts, waste, fitting, or other project-specific needs.
💵 Material cost
Estimate material cost from the adjusted project area and your own unit price.
This estimate does not automatically include labor, tax, delivery, or other project costs.
Area estimate disclaimer: This calculator is for planning and estimation. Actual material requirements can vary with layout, cuts, installation method, product dimensions, measurement accuracy, and site conditions. Confirm important quantities before purchasing.
Quick Answer
For a rectangular room measured in feet, square footage equals length × width: a 12 × 15 ft room is 180 ft². For an L-shaped room or irregular space, split it into non-overlapping simple shapes and add their areas. This calculator combines multiple rooms and reports both square feet and square meters.
How the area calculation works
Each space is calculated from the dimensions for its selected shape. The calculator converts the measurements to a common internal unit before combining the areas.
Quantity multiplies an individual area, and the optional allowance is applied only after all areas have been combined.
If you enter a material price, the estimated material cost uses the adjusted area after allowance, not the rounded display value.
Base Area is the sum of measured sections before allowance. Adjusted Area = Base Area × (1 + your allowance percentage ÷ 100). Estimated Material Cost = Adjusted Area in the selected pricing unit × your entered cost per area.
Supported shapes
- ▭ Rectangle
- Length × width
- □ Square
- Side × side
- △ Triangle
- Base × height ÷ 2
- ○ Circle
- π × radius²
- ⏢ Trapezoid
- (Base A + Base B) × perpendicular height ÷ 2
Irregular and L-shaped rooms
Split an irregular room into simple, non-overlapping rectangles, triangles, circles, squares, or trapezoids. Add each section as a separate area and let the calculator combine the results. Quantity covers repeated identical spaces. This avoids forcing a complex room into one inaccurate set of dimensions.
Choose feet, inches, meters, or centimeters for each section. A compound measurement such as 12 ft 6 in must first be converted to 12.5 ft or 150 in; it cannot be entered in one field as written.
Worked examples
One room: 12 ft × 15 ft = 180 ft².
L-shaped room: Add a 12 × 10 ft section (120 ft²) and a non-overlapping 5 × 8 ft section (40 ft²) for 160 ft² total.
Allowance and cost: A 12 × 15 ft room has 180 ft² Base Area. A 10% allowance makes 198 ft² Adjusted Area. At $4.50 per ft², Estimated Material Cost is $891.00.
Common room sizes
Reference areas for rectangular rooms, before any allowance. Actual rooms should be measured.
| Room dimensions | Square feet | Square meters |
|---|---|---|
| 10 × 10 ft | 100 ft² | 9.29 m² |
| 10 × 12 ft | 120 ft² | 11.15 m² |
| 12 × 12 ft | 144 ft² | 13.38 m² |
| 12 × 15 ft | 180 ft² | 16.72 m² |
| 14 × 14 ft | 196 ft² | 18.21 m² |
| 15 × 20 ft | 300 ft² | 27.87 m² |
| 20 × 20 ft | 400 ft² | 37.16 m² |
Method: dimensions are converted to meters for calculation; 1 ft² = 0.09290304 m². Results retain calculation precision and are rounded only for display. The conversion follows the exact foot-to-meter relationship documented by the National Institute of Standards and Technology (NIST). This is a geometric area estimate, not an official living-area measurement or a full project quote.
FAQ
How do I calculate the square footage of a room?
For a rectangular room measured in feet, multiply its length by its width. For other shapes, use the matching formula or add separate non-overlapping sections.
How many square feet is a 12 × 12 ft room?
A 12 ft by 12 ft room has 144 square feet of floor area before any allowance.
How many square feet is a 10 × 10 ft room?
A 10 ft by 10 ft room has 100 square feet of floor area before any allowance.
How do I calculate an L-shaped room?
Divide it into two non-overlapping rectangles, enter each as an area, then add their areas. The multi-area builder does that summation for you.
Can I calculate several rooms together?
Yes. Add a section for each room. Use Quantity for repeated spaces with the same shape and dimensions; sections may use different measurement units.
How do I calculate square footage with feet and inches?
Convert a compound measurement before entering it: 12 ft 6 in equals 12.5 ft or 150 in. Choose one unit for each dimension field; the calculator does not accept ‘12 ft 6 in’ in one field.
How do I convert square feet to square meters?
Multiply square feet by 0.09290304 to get square meters. The calculator reports both units and rounds only the displayed result.
What does the allowance percentage do?
It adds your chosen percentage to the combined Base Area to produce Adjusted Area. No allowance is applied unless you enter one, and no single percentage suits every project.
How is estimated material cost calculated?
Adjusted Area in the selected pricing unit is multiplied by your cost per square foot or square meter. Labor, tax, delivery, packaging, and other project costs are not automatically included.
Which shapes does the calculator support?
It supports rectangles, squares, triangles, circles, and trapezoids. Divide more complex spaces into supported, non-overlapping sections.