Calculate square footage for rectangular, circular, and triangular areas with unit conversion, perimeter for rectangles, optional cost per square foot, and practical material planning guidance.
Inputs and method
Choose rectangle, circle, or triangle, enter positive dimensions and units, and optionally enter cost per square foot. Dimensions are converted before applying the shape formula; optional cost multiplies unrounded area by the entered rate.
Calculations retain full floating-point precision until the labeled display step. Counts and packages use an explicit upward ceiling only where a whole purchase unit is required.
Interpreting the estimate
Use the result as a planning value and keep input precision consistent with the measurements or source data you have. Small displayed differences can come from final-place rounding; intermediate values are not rounded.
Assumptions and limits
Irregular boundaries, excluded areas, measurement tolerance, and installation waste are not inferred. Break complex spaces into measured shapes. Once the area is known, estimate materials with the tile calculator, concrete calculator, paint calculator, or mulch calculator.
Empty entries, invalid numbers, prohibited negatives, zero denominators, impossible relationships, and unsupported options trigger a validation message instead of a misleading result.
Separate shape measurements from pricing
Choose the shape and enter only the dimensions applicable to that shape, keeping each dimension’s unit visible. Save the resulting area before adding a price-per-square-foot assumption. This distinguishes the measured geometry from a purchasing or cost scenario that uses the area.
Sources
- SI Units — authoritative context for the stated definition, rule, model, or applicability boundary.
- Area measurement — authoritative context for the stated definition, rule, model, or applicability boundary.