Free Home Improvement Calculators
25 calculators for every home improvement math problem: paint, tile, concrete, board feet, R-value, HVAC BTU, and more. All free, all in-browser, all bookmarkable.
Paint & wall 4 calculators
Estimate materials for interior and exterior painting, wallpaper, and drywall projects.
Flooring & tile 3 calculators
Tile floors, walls, and backsplashes — with proper waste allowance.
Framing & lumber 3 calculators
Lumber math for framing, decking, and general carpentry.
Concrete & masonry 2 calculators
Slabs, footings, walkways, and driveways.
Roofing & exterior 2 calculators
Roof squares, siding, and outdoor coating.
HVAC & insulation 6 calculators
System sizing and comfort-envelope calculations.
Electrical 1 calculator
NEC-referenced sizing for common electrical calculations.
Landscape & yard 3 calculators
Mulch, seed, sprinklers, and outdoor projects.
Project cost 1 calculator
Estimate total project cost with regional variation.
Why we built 25 calculators
Every home reference site has articles. Almost none have working calculators. That's a mistake — the moment when a homeowner realizes they need 3.2 gallons of paint or 68 bags of concrete is the moment they'd otherwise leave for a home improvement store's calculator or a scattered spreadsheet.
All 25 calculators are free, run entirely in your browser (no data collected), and are cross-linked to the material and project pages relevant to each calculation. They're bookmarkable — save a link and the calculator opens ready to use.
Missing a calculator you want?
Suggest one via our contact page. Reader-requested calculators go into the roadmap. Recent additions from reader requests: Deck Stain Calculator, Ceiling Fan Sizing, and Attic Ventilation.
Frequently asked questions
Genuinely free, no signup, no email required. The site is funded by display ads (on non-emergency pages) and affiliate commissions from material/tool links. Calculators themselves don't cost you anything and don't collect your inputs. See our advertising disclosure.
Yes. Each calculator uses standard trade-appropriate waste factors — 10% for tile, 15% for hardwood flooring, 10% for lumber, and so on. Where waste factor is variable (irregular rooms, complex tile patterns), the calculator lets you adjust it.
Accurate for planning and budgeting purposes. Always verify with a professional for exact quantities on large or complex projects. The calculators use industry-standard formulas — the paint estimator uses 350 sq ft/gallon standard coverage; the concrete calculator uses standard bag yields; the R-value calculator references DOE climate zone recommendations.