About Tally & Square

Tally & Square is a small set of calculators built for one purpose: telling you exactly how much material to buy before you're standing in a hardware store aisle guessing.

Every formula on this site uses the same waste margins a contractor would use, and every result rounds to a real, purchasable unit — whole gallons, whole boxes, whole sheets. The math behind each number is shown on the page, so you can check it against your own tape measure.

This site is supported by display ads and affiliate links to retailers like Home Depot and Lowe's. If you buy something through one of those links, we may earn a small commission at no extra cost to you.