Free home calculators
Measure a room, price a floor, size a rug, check a stair. Each calculator draws what you enter, shows its formula and its sources, works in feet and inches or metres, and opens its result as a floor plan you can edit.
- Square footage calculatorEvery room's area and the total, sketched to scale.Area and size
- Flooring calculatorBoxes, waste by pattern and the installed cost.Materials
- Paint calculatorGallons or litres from the walls, less doors and windows.Materials
- Tile calculatorTiles, boxes, grout and mortar, with the pattern drawn.Materials
- Stair calculatorRisers, treads and angle, checked against the code.Stairs and structure
- Rug size calculatorThe right standard rug for your room and sofa.Rooms and furniture
- Cost to build a houseLow, likely and high, split by stage of the build.Cost
- BTU calculatorThe air conditioner size for a room, sun and people.Comfort
- Carpet calculatorSquare yards from the roll width, with the seams shown.Materials
- Drywall calculatorSheets, joint compound, tape and screws for the walls.Materials
- Wallpaper calculatorRolls, with the pattern repeat counted in.Materials
- Baseboard calculatorLinear feet less doorways, in stock lengths.Materials
- Cost per square footPrice per ft² and m², homes side by side.Cost
- What size bed fits my roomEvery bed size with the walkway around it.Rooms and furniture
- Room size calculatorArea, code minimums and how full the room is.Area and size
- Lumens calculatorHow much light a room needs, in lumens and bulbs.Comfort
- Square feet to square metresBoth ways as you type, with common sizes.Converters
- Feet and inches to metresLengths both ways, fractions of an inch included.Converters
- Roofing calculatorSquares and bundles from the footprint and pitch.Stairs and structure
- Concrete calculatorCubic yards and bags for a slab or footing.Stairs and structure
- Deck calculatorBoards, joists and screws for a deck.Stairs and structure
- Renovation budget plannerYour line items, totalled with a contingency.Cost
What makes these calculators different
- They draw what you type. The room, the walls, the stair or the rug appears to scale as you enter it, so a wrong number looks wrong.
- They show where the number comes from. A chart splits every answer into its parts: each room's share of the floor, what doors and windows take off the paint, where a build budget goes.
- They open as a plan. The button under each calculator builds a FloorGen project from your numbers: your rooms, named and sized, ready to arrange, furnish and see in 3D.
- They cite their defaults. Coverage rates, code limits and cost ranges name their source and date on the page, and every one is a field you can change.
When a calculator is enough, and when to draw
A calculator is the fastest answer for one room. Once there are several rooms, odd shapes or walls you might move, a floor plan keeps every number right as you change it: FloorGen labels each room with its net area, and its Schedules and budget panel adds up paint, flooring, tile and baseboard for the whole house.
Everything runs in your browser; nothing you type is sent anywhere. For the background, how to calculate square footage (ANSI Z765) explains which area a listing or appraisal uses, and materials estimate from a floor plan works through drywall, flooring and baseboard for a whole ADU.
Questions
Are these calculators free?
Yes, with no account and no limit. They run in your browser.
Can I use metres?
Every calculator that measures has a switch between feet and inches and metres.
How accurate are they?
The arithmetic is exact; the answer is only as good as the measurements and the assumptions. Each page names its defaults and their sources. Check the coverage on your can or box and type it in.
Can I share or save a result?
Copy link under a calculator copies an address with your numbers in it. Open as a floor plan saves them as a project in the FloorGen studio.
Can I put a calculator on my own site?
Yes. Embed under each calculator gives you the code for a frame with the calculator in it, free, with a link back to the full page.