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Area & volume

Area calculator

Combine rectangles, circles, triangles and deductions in metric or US area units. See clear formulas, worked examples, assumptions and a printable estimate.

Square Footage & Area Calculator

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Build your area

Add non-overlapping shapes. Subtract cutouts only within the included area, counting each cutout once. This calculator sums areas; it does not detect positions or intersections.

Result units & allowance

Allowance is added after exclusions for estimating materials. Net measured area remains separate. Enter 0 for area measurement only.

Optional cost estimate

Cost uses net area plus allowance. Set price to 0 to exclude cost. Changing units converts the rate; changing currency only changes its label.

How to useCalculation methodRead the project guide

How to use

  1. Choose rectangles, circles, triangles, trapezoids or known areas. Add non-overlapping pieces of the space.
  2. Mark cutouts as Subtract and enter quantities. Deductions must leave a positive net area.
  3. Choose a result unit, optional material allowance and price per displayed area unit.
  4. Use Copy net area for manual entry into another calculator; the tools do not automatically synchronize.

Calculation method

Rectangle: length × width. Circle: π × (diameter / 2)². Triangle: base × perpendicular height / 2. Trapezoid: (parallel side 1 + parallel side 2) × perpendicular height / 2. Known-area rows use the entered area. Multiply each by quantity, add included areas and subtract deductions. The main area result is net area. Allowance applies separately to the material target, and cost uses that target.

Worked example

A 4 × 3 m rectangle is 12 m² and costs 300 USD at 25 USD/m² without allowance. Subtracting 2 m² leaves 10 m²; a 10% allowance gives an 11 m² material target and 275 USD. A triangle of base 4 m and perpendicular height 3 m is 6 m². A trapezoid with parallel sides 4 and 2 m at height 3 m is 9 m².

Assumptions and limits

The calculator combines arithmetic areas; it does not detect overlapping shapes or infer boundaries from a drawing. It does not optimize cuts or produce whole material packs. An L-shaped area can be represented as an outer rectangle minus a cutout. Copy net area intentionally excludes the allowance so you can avoid applying it twice in a material calculator.

Units, prices and saved estimates

Physical values are stored internally in metres, square metres, cubic metres or kilograms as appropriate. Changing measurement units converts their display; choosing a currency changes its label without applying an exchange rate. Purchase quantities use unrounded calculations. Money is shown to two decimal places.

Edits can be saved in this tab. Optional device saving lasts seven days after the last save. Copy, TXT download and a separate printable report use the current valid estimate. Delete draft removes saved inputs without resetting the visible form. The privacy choices page can remove all calculator drafts.

For practical measurement decisions, read measuring composite areas and deductions.