How it works
Area counts unit squares that fit inside the rectangle; multiplication gives that count when sides are perpendicular.
Formula
A = length × width
How to use Area of a Rectangle Calculator
- Measure or enter the longer side (length) and shorter side (width).
- For a square, enter the same value twice or use side-only mode if available.
- Read area in square units.
- Combine with trapezoid or triangle tools for L-shaped lots by splitting shapes.
Worked examples
Concrete numbers and cases you can check against the tool above.
Room 12 ft × 14 ft
Area 168 ft² for carpet ordering before waste factor.
When to use Area of a Rectangle Calculator
Rectangles are the building block for rooms, screens, and fields. Area feeds into paint, flooring, and tile quantity estimates.
Common use cases
- Floor area for carpet or laminate ordering.
- Pixel area of a rectangular UI element.
- Basic land parcel math before surveying detail.
Inputs and outputs
- Length and width in matching units
Privacy
This tool runs entirely in your browser. Your data never leaves your device — nothing is uploaded to our servers.
Frequently asked questions
- Are length and width interchangeable?
- Yes for area — order does not change the product.
- What if sides are not perpendicular?
- That shape is a parallelogram, not a rectangle; this formula does not apply without height.
- How do I convert units?
- Convert both sides to the same unit before multiplying; area units square the length unit.