Frequently Asked Questions

How HomeMath works and how its calculators measure. Questions about a single calculator are answered on its own page.

What is HomeMath?

HomeMath is a set of 25 free calculators for concrete, block, gravel and paver projects, made by Dross Creative. Each one runs in your browser and shows the answer as you type; the home page lists them all.

Is HomeMath free?

Yes. Every calculator is free to use, with no account, no sign-up and nothing to install.

Are the sizes and prices I enter stored or sent anywhere?

No. The calculations run in your browser, and the numbers you type are not sent to us. They only leave the page if you copy a link to a calculation and share it, because the link carries the inputs. When someone opens such a link, our analytics may record its address, inputs included, with that page view.

Which units do the calculators use?

US customary units by default, and metric at the switch above each calculator. In US units, length fields take feet, inches or yards, thicknesses and diameters are in inches, and volumes come out in cubic yards and cubic feet (27 cubic feet make a cubic yard). In metric, lengths are in meters or centimeters, thicknesses in centimeters, volumes in cubic meters and liters, and areas and prices per square meter. Bag counts are for the 40, 60 and 80 lb bags sold in the US (and in the fence post and sonotube calculators also the 50 lb fast-setting bag), shown with their weight in kilograms in metric, where you can also type your own kilogram bag's yield in liters from its label. The block calculator counts the US 8 × 8 × 16 in block, and in metric the block size you pick or type in millimeters. The concrete mix calculator counts 94 lb bags of Portland cement, and the self-leveling concrete calculator 50 lb bags of underlayment at the yield you type.

Why do the price fields already have numbers in them?

In the cost, block, concrete wall and retaining wall block calculators they are round example numbers that show how the estimate works, not market averages or quotes; replace them with your supplier's prices before you rely on a total. The slab price, driveway, patio, paver, concrete removal, foundation and block wall cost calculators, and the gravel prices per ton and per yard, come from published US ranges instead, named with their source and date on each page; the paver cost calculator's bag and compactor prices start at Lawn Love's, and the gravel and paver calculators' own price fields start empty. HomeMath has no local price data.

Does every calculator add extra for waste?

The concrete, pad, cost, block, fence post, sonotube, concrete wall, concrete mix and self-leveling concrete calculators add a waste allowance of 10% by default, and show the amount without it as well. Change the field to suit your job, or set it to 0 for the exact volume. The driveway, patio and foundation cost calculators add a fixed 10% to the concrete to order, and the slab price, removal and wall cost estimates add none, since they price the area. The gravel and gravel driveway calculators add an editable 10% extra, the paver base calculator 20% to the base gravel for compaction, the paver calculator the waste of the laying pattern (10% or 20%), and the rebar calculator 5% on the bar and mesh, all of which you can change. The concrete weight calculator adds none: it weighs the volume you enter.

Can HomeMath replace a contractor's quote or an engineer?

No. HomeMath computes quantities and costs from the sizes and prices you enter; it doesn't design footings, check loads or know your local code. Use it to plan and to check quotes, and follow your plans, your building department and the product instructions for anything structural.

Can I share a calculation?

Yes. Every calculator has a copy-link button; the link opens the same calculator with the same sizes and prices filled in, for a helper, a supplier or your own notes.