MeasureSparkConversions
Rectangle Area Calculator
Use the same unit for both dimensions. This version is set up for feet and square feet.Enter your measurements
Area = length × width.
How this estimate works
Area = length × width.
Measure twice and use the same unit throughout. Product coverage, material density, installation patterns, and local requirements can change the quantity you need.
Quick answer
For a rectangle, multiply length by width to get square units. Keep both measurements in the same unit; feet multiplied by feet gives square feet.
Worked example
A 12 ft by 10 ft rectangle has an area of 120 ft². Two such sections total 240 ft² before adding any project-specific waste allowance.
Assumptions
- The measured shape is rectangular.
- Length and width use the same unit.
- The result is geometric area and does not include material waste.
How do I calculate an irregular room?
Split the outline into non-overlapping rectangles, calculate each area, and add the results. Measure alcoves separately and subtract openings or fixed footprints only when they are outside the project scope.
Why are square feet different from feet?
Feet measure one-dimensional length. Square feet measure a surface: each square foot is a square one foot long by one foot wide. The unit is squared because two length dimensions are multiplied.
Can square footage determine material quantity?
It provides the base area. Flooring, tile, paint, and landscaping materials also depend on coverage, cuts, coats, depth, package rounding, and installation requirements, so use the relevant project calculator next.
Last reviewed September 22, 2026. Source: NIST guidance for calculating area and volume. Product instructions take priority over a general estimate.