About Backyard Math Hub

Backyard Math Hub is built by Jim Frith, who also makes NECCalcHub (electrical calculators) and The College Recruiting Playbook. It started with a familiar problem: standing in a home-center aisle trying to work out how many bags of concrete a fence post really takes, or whether a 20×20 bed needs 30 bags of mulch or 50.

How we build the calculators

• We start from geometry (volume = area × depth) and use published manufacturer data, such as the QUIKRETE Concrete Mix yields, wherever it exists.
• Where a figure varies by supplier (gravel density, paint coverage), we use a typical value, say so on the page and let you change it.
• Every calculator is tested against hand calculations before publishing.

What we don't do

We aren't engineers, and these tools don't replace building codes, permits or a pro's site assessment. For structural work (deck footings, tall retaining walls), follow your local code and the manufacturer's specifications.

How the site is funded

The site is supported by display ads (Google AdSense), Amazon affiliate links (as an Amazon Associate we earn from qualifying purchases) and an optional printable worksheet. None of these changes the math.

Questions or corrections? Contact us.