Square Footage Calculator
Calculate area and perimeter for rectangles, triangles, and circles.
What this calculator does
The selected standard geometry formula is applied after unit normalization.
Shape dimensions
Split complex plans into simple non-overlapping shapes, calculate each, then add the areas.
Your plan updates instantly
Drag with a mouse or finger. Pinch or scroll to zoom.
The selected standard geometry formula is applied to normalized dimensions.
The arithmetic uses the exact values shown above. Verify field measurements, product pack sizes, layout constraints, and local requirements before ordering or building.
How to interpret the result
The selected standard geometry formula is applied after unit normalization.
How the result is calculated
Rectangle L x W; triangle base x height ÷ 2; circle πr².
Worked example
A 12 x 10 ft rectangle contains 120 ft² and has a 44 ft perimeter.
Practical guidance
- Measure the project at least twice before ordering.
- Use actual product dimensions and package coverage.
- Keep a saved or printed copy of the inputs used for the estimate.
Assumptions and limitations
Triangle perimeter assumes an isosceles triangle because only base and height are entered.
Methodology
Calculations use standard geometry and normalized units. Countable products are rounded up where partial products cannot normally be purchased.
Read the complete calculation methodology and testing policy.
Frequently asked questions
Are results rounded for purchasing?
Countable materials and packages are rounded up. Measured area, length, volume, and cost remain decimal values where appropriate.
Is this a final construction specification?
No. It is a transparent planning estimate. Verify product instructions, site conditions, plans, and local requirements.