- Free square footage calculator
- Multiple shapes & rooms
- Feet, inches, yards & metric
Square Footage Calculator
Use this square footage calculator to calculate square feet for a room, floor, house section, building area, or other space. Enter your dimensions, choose the shape and measurement unit, and get the total area instantly. You can add multiple rooms, subtract openings, include an optional waste allowance, and view the result in square feet, square yards, and square meters.
For a rectangle, multiply length by width. A room that measures 12 ft × 10 ft has an area of 120 sq ft.
Square Footage Calculator
Calculate one or multiple areas, subtract openings, add waste, and export a professional result.
How to Use the Square Footage Calculator
This online square footage calculator works for one room or several areas in a single calculation.
Choose the measurement unit
Select feet, feet + inches, inches, yards, meters, or centimeters. Changing the unit converts existing dimensions instead of clearing them.
Select the area shape
Choose rectangle, square, triangle, circle, semicircle, trapezoid, or parallelogram. The correct fields appear automatically.
Enter your dimensions
Type the length, width, side, diameter, base, or height. Add more rooms with Add Area, or remove openings with Subtract Area.
Review the final area
The calculator updates gross, subtracted, net, and final area automatically and also shows square yards and square meters.
Square Footage Formula and Area Calculation
The correct formula depends on the shape of the area. Keep dimensions in compatible units before calculating.
If a room measures 12 feet long by 10 feet wide, the calculation is 12 × 10 = 120 square feet.
- Length and width should use the same unit
- Feet × feet = square feet
- Meters × meters = square meters
When a measurement includes feet and inches, convert the inches into a fraction of a foot before multiplying. The calculator handles this automatically in Feet + Inches mode.
Length × WidthSide²(Base × Height) ÷ 2π × Radius²(π × Radius²) ÷ 2((B1 + B2) ÷ 2) × HeightSquare Feet Calculation Examples
These examples show how to find square footage for common room and shape measurements.
12 ft × 10 ft room
Length: 12 ft
Width: 10 ft
Calculation: 12 × 10
14 ft × 12 ft bedroom
Length: 14 ft
Width: 12 ft
Calculation: 14 × 12
Triangle area
Base: 12 ft
Height: 8 ft
Calculation: (12 × 8) ÷ 2
Square Feet, Square Meters, and Square Yards
Use these reference values when converting common area measurements.
| Conversion | Value | Use |
|---|---|---|
| 1 square foot | 144 square inches | Small surface measurements |
| 1 square yard | 9 square feet | Flooring and larger areas |
| 1 square meter | ≈ 10.7639 square feet | Metric-to-US conversion |
| Square feet → square meters | sq ft × 0.09290304 | US-to-metric conversion |
| Square meters → square feet | m² × 10.7639 | Metric-to-US conversion |
Room Square Footage Calculator
A room square footage calculator helps measure floor area from room dimensions. For a simple rectangular room, multiply the length by the width. For a room with alcoves, extensions, or multiple sections, calculate each area separately and add the results together.
House and Home Square Footage Calculator
A house square footage calculation can be built room by room or section by section. Name each area in the calculator, enter its dimensions, and add the sections together. If part of a measured plan should not be included, use Subtract Area.
Building and floor area calculator
The same area formula can be used for many floor and building sections. Because measurement standards can differ by purpose, this calculator should be treated as a dimension-based area tool rather than an official property-record measurement system.
Irregular square footage calculator
For irregular areas, divide the space into simpler shapes such as rectangles, triangles, circles, or trapezoids. Calculate each section, then combine the areas. The multiple-area feature makes this easier without forcing the whole space into one shape.
When to use the waste allowance
The optional waste field can be useful when the measured square footage is being used to estimate materials that require cuts or extra coverage. The appropriate percentage depends on the material and project, so confirm the recommended allowance before purchasing.
Frequently Asked Questions
Quick answers about square footage, room area, dimensions, conversions, and irregular shapes.
How do you calculate square footage?
For a rectangle, multiply length by width using the same unit. For example, 12 ft × 10 ft = 120 square feet.
What is the square footage formula?
The basic rectangle formula is Area = Length × Width. Other shapes use their own formulas, such as (Base × Height) ÷ 2 for a triangle.
How do I measure square footage of a room?
Measure the room length and width and multiply them. For irregular rooms, divide the space into simple shapes and add the areas together.
Can I calculate multiple rooms at once?
Yes. Use Add Area for each room or section. The calculator totals them and can also subtract openings or excluded spaces.
Can I calculate square footage with feet and inches?
Yes. Select Feet + Inches from the measurement unit menu and enter each required dimension using separate feet and inches fields.
How do I convert square feet to square meters?
Multiply square feet by 0.09290304. The calculator also displays the final result in square meters automatically.
Can this calculate triangle or circle square footage?
Yes. The calculator supports triangle, circle, semicircle, rectangle, square, trapezoid, and parallelogram area calculations.
Can I use this for tile, flooring, paint, roof, wall, deck, or lawn projects?
The area result can help with many projects, but dedicated calculators for those topics can include material-specific coverage, waste, and project rules.
Useful Area and Material Calculators
Use dedicated calculators when you need project-specific estimates beyond general square footage.