About Trowelly

Trowelly is an independent website with 15 free calculators for home and yard projects: concrete, gravel, mulch, topsoil, paint, drywall, flooring, tile, roofing, decking, fencing and more. The goal is simple: help you work out what to buy, in the units your supplier sells, before you get to the store.

How the calculators work

Each calculator turns your measurements into a volume, area or count, adds a waste allowance you can change, and converts the answer into the units you actually buy: bags, cubic yards, tons, sheets, boxes or bundles. Every page explains its formula, lists the assumptions it makes (such as material density or bag yield) and works through an example, so you can check the maths yourself.

The formulas are covered by automated tests that run every time the site changes. When we find a mistake, we fix the formula and the tests together.

What the results are, and are not

Results are planning estimates. Real materials vary: gravel is heavier when wet, paint coverage depends on the surface, and suppliers round loads differently. Use the numbers to plan and budget, then confirm with your supplier, the product label and your local building codes. See the disclaimer for details.

Privacy by default

The calculators run in your browser. There is no sign-up, and the project planner is stored on your own device. Read the privacy policy for the full picture.

Get in touch

Spotted an error, or want a calculator we do not have yet? Email info@trowelly.com or use the contact page.