How we calculate
Last updated
Every calculator and cost guide on this site follows the same rules.
Quantities
- We use standard geometry (length × width × depth) and convert units the usual way: 27 cubic feet per cubic yard.
- Coverage and yield figures, such as how much concrete one bag makes, come from the manufacturer's data sheet. We link to it on the page.
- Bags, pallets and boards are rounded up, because you can't buy part of one.
- Extra for waste is your choice. We show the default and you can change it.
- Each formula is tested with worked examples before we publish it.
Prices
- Prices are shelf prices we checked online for specific stores. Our reference locations are Penitas, TX (78576) , Columbus, OH (43215) and Sacramento, CA (95814) . If a product isn't sold or isn't in stock near one of them, we say so and leave that location out.
- Every price shows the store, location and date. We show ranges instead of a single number.
- We recheck prices at least every six months. Old prices are flagged before they can be published.
- Prices exclude sales tax and delivery. Your local price may be different, so every calculator lets you type it in.
Labor costs
When we estimate what a contractor's labor might cost, we use wage data from the US Bureau of Labor Statistics and say which year and occupation we used. A real quote includes overhead and profit, so treat our estimate as a floor, not a quote.
What we don't do
- We don't invent numbers. If we can't verify a figure, we leave it out.
- We don't accept payment to change a price, a ranking or a recommendation.
- We don't replace your local building code, a permit or a professional for structural work.
Corrections
If you spot an error, contact us. We fix it and update the date on the page.