Work out your home project before you call a contractor
Free calculators and plain-English guides to work out what a home project needs, with the math and sources shown.
- The math is shown on every tool
- Sources linked in every guide
- Runs in your browser, no sign-up
- International Residential Code
- OSHA and EPA rules
- ENERGY STAR
- Manufacturer data sheets
Calculators and guides
Start with the measurements every estimate depends on. Honest cost guides come next, once we have real quotes to check them against.
Roofing
Measure pitch, roof area and rafters, and work out how many shingles to buy.
All 11 roofing guidesConcrete and block
Work out cubic yards, bags and blocks for slabs and walls.
All 12 concrete and block guidesStart with these
Roof Pitch Calculator
Enter the rise and run to get your roof pitch, angle, grade and slope multiplier, with a pitch-to-angle chart and the formula shown.
Shingles and materialsShingle Calculator: How Many Bundles Do You Need?
Enter your roof area and waste allowance to get squares and shingle bundles, with the formula and manufacturer guidance on bundles per square.
Concrete and block quantitiesConcrete Slab Calculator: Cubic Yards and Bags
Enter your slab's length, width and thickness to get cubic yards and the number of 80, 60 and 40 lb bags, with the formula and a worked example.
PaintPaint Calculator: How Much Paint Do You Need?
Work out how many gallons a room needs from its size, coats and your paint's coverage, with the published range shown to show how much the product matters.
Flooring and tileFlooring Calculator: Area, Waste and Boxes
Work out your floor area, order area and whole boxes for hardwood, laminate or vinyl plank, with the waste assumption shown so you can change it.
Decks and stairsStair Calculator: Risers, Treads and Total Run
Enter your total rise and tread depth to get risers, treads, run and angle, compared with named 2021 IRC figures, with the renumbered 2024 sections noted.
Built to be accurate, and to prove it
Guidance is only useful if it's right. Every guide goes through the same process before it's published.
The math is visible
Each calculator explains its formula and works through an example you can check by hand.
Sources you can check
Figures link to the code section or manufacturer document they come from.
Rules of thumb are labeled
Where a number is only an estimate or planning allowance, we say so, and you can change it.
No invented prices
We won't publish a cost range until real quotes back it up.
Frequently asked questions
Are the calculators free?
Yes. They run in your browser, need no sign-up, and don't send what you type anywhere.
Why are there no prices yet?
Prices vary by region, roof and contractor. We don't want to repeat other sites' ranges or publish unsourced averages, so cost guides will only go live once real quotes back them up.
Can I use these numbers to order materials?
Use them to plan and to check a quote. Before you order, confirm your measurements on site and check the product's own coverage figures.
Are you a contractor or lead service?
No. We don't do building work, and we don't sell your details to contractors.
Spot something wrong?
Tell us the page and what you found. We check it against the source and correct it.