Free DIY & construction calculators

Measure once, buy right. Quick, accurate calculators for home and garden projects, in feet or metres, that work on your phone at the hardware store.

Plan a project

Most jobs need more than one calculation. Start here and work through the tools in order.

Measure the area, order compacted gravel for the base, then work out the concrete and bags for the slab.

Fill the bed with topsoil (plus a little extra for settling), then finish with a layer of mulch.

Board the walls, paint them, then lay the new floor, with the right number of sheets, cans and boxes.

Find the air conditioner size a room needs from its floor area, sun, ceiling height and how many people use it.

Measure. Each calculator shows a diagram of exactly what to measure. Use feet, inches, metres or centimetres.
Calculate. Results update as you type, with bags, boxes, sheets or cans to buy, plus waste and cost.
Buy and share. Print the result, copy it, or copy a link to send the exact numbers to a partner or contractor.

Imperial and metric. Mix feet, inches, metres and centimetres. We convert everything for you.
Real shopping numbers. Bag counts, waste allowance and a cost estimate, not just a raw volume.
Fast and private. Every calculation runs in your browser. No sign-up, nothing to install.
Explained, not just calculated. Each tool shows the formula and a worked example so you can check the math.