About

QuantityGuru publishes free calculators that answer one practical question: how much of a material do I need to buy? Each calculator takes your measurements, shows the amount to order, and lists the steps behind the number so you can check it yourself.

What we cover

Concrete and masonry, landscaping and soil, paint and flooring, roofing, decks and fencing, and pool volumes. Every calculator has its own page with a plain-language explanation, worked examples, buying notes and common mistakes, and many sizes have a ready-made answer page.

How the numbers are worked out

The formulas are standard geometry and widely used rules of thumb, such as 27 cubic feet in a cubic yard, 100 square feet in a roofing square and 7.48 gallons in a cubic foot. Each page states the assumptions it uses (for example the yield of a concrete bag, the coverage of a gallon of paint or the weight of a cubic yard of gravel) so you can swap in the figure printed on your own product.

Accuracy and limits

Results are planning estimates. Real jobs depend on site conditions, waste, product coverage and installation method, and the cost ranges shown are rough averages that vary by region and supplier. Always confirm quantities with your supplier or contractor and follow local building codes and manufacturer instructions.

Corrections

If you spot a mistake in a formula, a figure or an explanation, please tell us on the contact page. We review reports and fix errors.