Measure twice, cut once
Square footage calculator
Length times width, with as many areas as your project has. Every job starts here — and the formula is right on the page.
Turning area into materials? Cubic yards, tile, drywall, and sod pick up from here.
Cubic feet in one cubic yard — the divisor behind every soil, gravel and concrete order.
What one cubic yard covers at an inch deep. Divide by your depth in inches for your coverage.
The extra to order for cuts, breakage and bad luck. Each material calculator carries its own waste default.
Every formula on this site is shown on the page — check it against any estimate you're handed.
All the calculators
Board Foot CalculatorBoard feet from thickness, width and length, with optional cost.
Sod CalculatorSquare feet of sod for your yard, with a waste allowance.
Tile CalculatorHow many tiles you need from room size, tile size and waste.
Drywall CalculatorSheet count for walls and ceilings.
Stair Stringer CalculatorRise, run and stringer length from your total rise.
BTU CalculatorRough heating/cooling BTU estimate from room size.
What's the catch?
There isn't one. Every calculator here is free, there's no signup, and nothing you type leaves your browser — the math runs on your device. No ads, and your measurements are never stored or sold. The site is run by one independent builder whose paid products cover the bills.
These are ordering estimates, not engineering. Measure your own project, round up on concrete, and when structure or code is involved, your local building department has the final word.
How this is calculated
Square feet = length × width, per rectangle, summed. Square yards = square feet ÷ 9. Square meters = square feet × 0.0929.
Rooms are rarely perfect rectangles — split an L-shape into two rectangles, measure each, and add them. Closets and alcoves count if they get the same flooring.
Common questions
How do I measure an L-shaped room?
Split it into two rectangles at the corner, measure each one, and add them together — that's what the multiple-area rows are for.
Do I measure walls or floor?
This page figures floor (or ceiling, or yard) area. For wall area — like for drywall or paint — the drywall calculator handles walls and ceilings together.
How much extra should I buy?
That depends on the material, which is why each material calculator carries its own waste factor — tile and sod default around 10%. Cutting it exact is how projects come up one box short.
Who makes this
Built by one person, in the open.
MeasureTwiceMath is made by Jon, a product designer outside Chicago. He also runs Jon's Reminders, a text reminder service he built for his own parents.
These tools give material estimates. They don't replace measuring carefully or checking your local building code.