TrowelMath publishes free construction and DIY material calculators for DIYers and contractors estimating concrete, paint, mulch, gravel and room AC size before buying materials. Every tool runs in your browser, needs no sign-up and shows how its answer was reached.
Who runs TrowelMath
TrowelMath is an independent site edited by Alex. We are a small team, not a bank, payroll provider, retailer or advisory firm, and we do not sell your data. You can reach us through the contact page.
What makes the tools different
- Sources you can check. Every data point names its source and period on the page where it is used.
- Working shown. Formulas and worked examples sit next to each calculator, so you can check a result by hand.
- Tested code. The calculators share one tested engine. Our automated tests cover unit conversions between feet, inches, yards and metres, bag rounding and waste allowances.
- Private by design. The numbers you type stay on your device; we do not run analytics that record them.
Methodology in brief
Volumes are length × width × depth with the waste allowance you choose. Bag counts use manufacturer yields (40/50/60/80 lb = 0.30/0.375/0.45/0.60 cu ft). Paint uses 350 sq ft per gallon unless you change it; door and window deductions are 20 and 15 sq ft. Room AC sizes follow the ENERGY STAR chart and adjustments.
Full details are on our editorial policy and methodology page.
How the site is funded
TrowelMath is free to use. It may show advertising and earns a commission on some product links; see the affiliate disclosure. Money never decides what a calculator says.
Corrections
If you find an error, tell us with the page address. We check every report, fix confirmed errors, and note the update date on the page.