About MaterialCalc

MaterialCalc is a small set of free calculators for people ordering building and garden materials. The goal is simple: give you the number you need, in the unit you actually buy, without making you read a 2,000 word article first.

How the numbers are calculated

Every calculator uses published rules of thumb and converts them into volume. Coverage figures, bag yields and material densities are listed on each calculator page, along with the assumptions behind them, so you can check the maths yourself.

Where a material's density or coverage varies by product, the calculator uses a middle-of-the-road figure and says so. Your supplier's spec sheet is always the final word.

Corrections

If a figure looks wrong to you, it may well be — supplier specs change. Get in touch and it will be checked and corrected.

Last updated 2026-09-30.