MATERIALS & MEASUREMENTS

Room Area Calculator

Calculate square feet, square meters, and the perimeter of rectangular rooms. Estimate multiple identical rooms without repeated manual math.

Interactive estimate · Private on your device

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Change any number to refresh the results instantly.

Project details

All fields editable

All starter prices are illustrative user-editable inputs, NOT verified quotes or live market data. The currency switch relabels amounts; it never converts exchange rates.

YOUR PROJECT ESTIMATE Live calculation

Input values used

Measurements: imperial. Prices: USD (user-entered; no currency exchange).

Room length12 ft
Room width15 ft
Identical rooms1

Area and dimension results

Area per room180 ft²
Total area180 ft²
Perimeter per room54 ft
Total in square feet180 ft²
Total in square meters16.72 m²

Calculation assumptions

  • Assumes rectangular rooms with no alcoves or obstructions.
  • Perimeter is shown per room; repeated rooms are assumed identical.

Compare two scenarios

Save the current estimate to A or B, change inputs, then compare. Stored only in this browser.

Planning estimates only. They are not binding contractor quotations, local price checks, or certified engineering advice. Inputs are calculated on this device; none are sent to our servers.

How to use this calculator

  1. Measure the interior length and width of a rectangular room.
  2. Choose the unit system you used to measure.
  3. Enter the number of identical rooms, then review both area units and perimeter.

The calculation formula

Area per room = length × width; total area = area per room × number of rooms; perimeter = 2 × (length + width).

Worked example

A 12 ft × 15 ft bedroom covers 180 ft² (approximately 16.72 m²), with a perimeter of 54 ft. Two identical bedrooms cover 360 ft².

Assumptions and limitations

  • L-shaped rooms need to be split into rectangles.
  • Measurements do not account for walls, built-ins, or measurement error.

Actual project costs may be affected by supplier rates, material grade, labor market, location, disposal, site condition, access, permits, taxes, and schedule. All entered prices are yours to revise. See our methodology and disclaimer.

Frequently asked questions

Does this calculate wall area?

No. Floor area and perimeter are separate from wall surface area. Use the paint calculator for walls.

Can I use meters?

Yes, switch to metric; both square meters and square feet are always reported.