Square Footage Calculator
Square footage calculator for rooms, floors, walls, gardens, and home projects. Enter length and width in feet, inches, yards, or meters to calculate square feet, square meters, perimeter, waste allowance, and estimated material cost.
To calculate square footage, convert both dimensions to feet and multiply length by width. A 12 ft by 10 ft room is 120 square feet. If you are ordering flooring, tile, carpet, or landscaping materials, add a waste allowance so your purchase covers cuts, mistakes, and irregular edges.
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Result
Enter values above and click Calculate to see your result.
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How to Use This Calculator
Enter the room or surface dimensions
Type the length and width of the space you want to measure, such as a room, patio, wall, or lawn.
Choose the unit you measured in
Select feet, inches, yards, or meters. The calculator converts both dimensions to feet before finding area.
Add waste or cost if needed
Use waste allowance for flooring, tile, carpet, sod, or other materials. Add cost per square foot if you want a quick material estimate.
Review area, perimeter, and adjusted total
Use square footage for measurement, perimeter for edge planning, and waste-adjusted area for ordering materials.
Formula
How it works: Convert both measurements to feet, then multiply length by width. Optional waste allowance adds extra square footage for cuts, mistakes, and irregular edges.
Review and Methodology
This calculator runs locally in your browser. Inputs are converted into the units required by the formula, and the result is paired with supporting references so you can verify the method before using it for planning or estimates.
Reference sources
- NIST Guide for the Use of the International System of Units (SI)
- BIPM SI Brochure, 9th edition
- Industry planning norms for flooring and tile waste allowances
Worked Example
How to Calculate Square Footage
Square footage measures flat area. For a rectangular room, wall, lawn, patio, or floor, the calculation starts with length times width after both measurements are in feet.
- For feet: multiply length by width directly. A 12 ft by 10 ft room is 120 sq ft
- For inches: convert each dimension to feet first by dividing by 12, then multiply
- For yards: multiply each dimension by 3 to convert to feet before finding area
- For meters: multiply each dimension by 3.28084 to convert to feet, or use the square-meter result directly
- Waste allowance helps with cuts, breakage, and irregular edges when ordering flooring, tile, carpet, sod, or other materials
Use the base square footage for measurement and the waste-adjusted area for ordering materials. For depth-based projects, use a volume calculator such as concrete, mulch, or room volume.
You can also calculate changes using our Tile Calculator, Concrete Yardage Calculator, Mulch and Soil Calculator, Rectangle Volume Calculator or Parallelogram Area Calculator.
Common Square Footage Planning Uses
Typical ways square footage is used for rooms, flooring, landscaping, and project estimates.
| Project | What to Measure | Typical Extra | Related Tool |
|---|---|---|---|
| Flooring or carpet | Room length x width | 5% to 10% | Tile Calculator |
| Tile layout | Floor area plus tile size | 10% to 15% | Tile Calculator |
| Concrete slab | Length x width plus depth | 5% to 10% | Concrete Yardage Calculator |
| Mulch or soil | Bed area plus depth | 5% to 15% | Mulch and Soil Calculator |
| Land area | Total flat area | None unless ordering material | Square Footage Calculator |
Note: Waste percentages are planning rules of thumb. Always check supplier guidance and product coverage before ordering.
Frequently Asked Questions
How do I calculate square footage?
Measure length and width in feet, then multiply them. A room that is 12 feet long and 10 feet wide is 12 x 10 = 120 square feet.
How many square feet is a 10 by 12 room?
A 10 ft by 12 ft room is 120 square feet. If you add 10 percent waste for flooring, plan for about 132 square feet of material.
Can I use inches, yards, or meters?
Yes. The calculator converts inches, yards, and meters to feet before calculating area. It also reports the result in square meters for metric planning.
What waste allowance should I use for flooring?
For simple rectangular rooms, 5% to 10% is common. For diagonal layouts, many cuts, closets, or irregular rooms, 10% to 15% is safer.
Is square footage the same as perimeter?
No. Square footage measures area, while perimeter measures distance around the edge. A 12 ft by 10 ft room has 120 sq ft of area and 44 ft of perimeter.
How do I estimate cost from square footage?
Multiply the waste-adjusted square footage by cost per square foot. For 132 sq ft at $3.50 per sq ft, estimated material cost is 132 x 3.50 = $462.
Can I use this Square Footage Calculator on my own web page?
You can. Look for the "Embed" button near the top of this calculator. It lets you pick a size, border style, and color palette, then gives you an iframe tag to paste into any webpage. The widget is responsive, loads fast, and costs nothing. More details at calculory.com/services/embed-calculators.
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I can help you understand the square footage calculator formula, interpret your results, and answer follow-up questions.
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