Free home project calculators
Free home project calculators for roofing, concrete, paint, flooring, decks, fences, gutters, room AC, water heaters and insulation, with formulas shown.
Each tool runs entirely in your browser and shows its method on the page. Nothing you type is stored or sent anywhere.
| Tool | What it works out | Based on |
|---|---|---|
| Roof pitch calculator | Pitch, angle, grade and slope multiplier | Geometry; OSHA's slope definitions |
| Rafter length calculator | Rafter length and shortest stock length | Geometry |
| Roof area calculator | Roof area and roofing squares | Footprint and pitch |
| Shingle calculator | Squares and bundles | GAF's bundle guidance |
| Concrete slab calculator | Cubic yards and bags | QUIKRETE published yields |
| Concrete block calculator | Blocks, courses and mortar | Titan America's estimating guide |
| Concrete footing calculator | Cubic yards and bags for a footing | QUIKRETE published yields |
| Sonotube concrete calculator | Cubic yards and bags for round columns | Geometry; QUIKRETE published yields |
| Fence post concrete calculator | Concrete around each post | Geometry; QUIKRETE published yields |
| Concrete weight calculator | Estimated weight of a slab | QUIKRETE typical unit weight |
| Metal roof calculator | Panels and roof area | Panel coverage you enter |
| Attic ventilation calculator | Net free vent area | 2021 IRC Section R806.2 |
| Paint calculator | Gallons and quarts for a room | Coverage you enter; published product ranges |
| Flooring calculator | Order area and whole boxes | Box coverage you enter |
| Tile calculator | Tiles, grout volume and thin-set bags | Geometry; CUSTOM MultiSet coverage |
| Stair calculator | Risers, treads and run | Geometry; 2021 IRC Section R311.7 |
| Baluster calculator | Baluster count and gap | Geometry; 2021 IRC Section R312.1.3 |
| Deck materials calculator | Boards, joists and fasteners | Geometry; 2021 IRC Table R507.7 |
| Gravel, mulch and soil calculator | Cubic yards, bags and weight range | Extension formula; commercial density ranges |
| Room AC calculator | Room AC capacity | ENERGY STAR table |
| Water heater worksheet | Peak-hour demand | PNNL rule; secondary usage values |
| Tankless calculator | Heat output needed | Water heating physics |
| Drywall calculator | Sheets, screws, tape and compound | USG's material table (older guide) |
| Egress opening calculator | Clear opening compared with code figures | 2021 IRC Section R310 |
| Bathroom clearance checker | Your layout compared with code minimums | 2021 IRC P2705.1, P2708.1, R305.1 |
| Fence calculator | Posts, rails and pickets | Geometry; rule-of-thumb spacing |
| Gutter flow calculator | Flow and downspout count | 2021 IPC Equation 11-1 and tables |
| Attic insulation calculator | R-value and depth to add | 2021 IRC and ENERGY STAR tables |
| Concrete steps calculator | Cubic yards and bags for solid steps | Geometry; QUIKRETE published yields |
| Rebar calculator | Bars, stock lengths and weight | Geometry; commonly listed bar weights |
| Hip roof calculator | Area, ridge, hips and eaves | Geometry |
| Paver calculator | Pavers, bedding and base | Geometry; base depth you enter |
| Baseboard calculator | Feet and pieces | Geometry |
| Wallpaper calculator | Strips and rolls | Roll label you enter |
| Carpet calculator | Carpet to buy and layout | Geometry; roll width you enter |
How we build our tools
Each calculator uses a formula you can check by hand, and each page works through an example. Automated tests check the math against those examples. Allowances for waste are planning figures, and you can change them.
Each tool can also show the math with your own numbers, show how the result changes in a what-if table, copy your results, and download a full PDF report that's created in your browser, with your results, inputs, the working, a what-if table, a checklist, questions to ask and sources. "Copy link" puts your numbers in the web address, so anyone you share it with can see them. Nothing is sent to us when you use the tools, though like any web address, a link you open is recorded in our host's server logs.
These tools are for planning. Confirm measurements on site, and check code and product requirements before you buy or build.