About BuildKit Calculators
BuildKit Calculators is a set of free online calculators that help homeowners, DIYers, landscapers, painters and small contractors work out how much material a job needs before they buy. It covers concrete, gravel, mulch, topsoil, paint, drywall, flooring, tile, roofing, fencing, pavers, rebar and brick and block.
BuildKit Calculators is an independent construction-calculator website. It is not related to Docker's BuildKit, the container build tool, or to any other product that shares the name.
How the calculators work
- Real formulas. Every result comes from a fixed formula shown on the page, such as volume = length × width × thickness for a slab. No AI is used to produce the numbers.
- Waste included. Each calculator adds a waste or overage allowance that you can change, and rounds up to whole bags, boxes, sheets or bundles.
- Imperial and metric. Switch between feet, inches, yards and gallons, or metres, centimetres and litres.
- Private. Calculations run in your browser. The measurements you enter are not sent to us.
- Quantities, not prices. We never assume prices. If you enter your supplier's price, the calculator multiplies it for you.
How accurate are the results?
Results are estimates for planning. Product yields, supplier specifications, site conditions and local building codes vary, so confirm quantities with your supplier or a qualified professional before you buy or build. Each calculator page lists its assumptions, and we check the formulas against worked examples.
The calculators
- Concrete Calculator: Cubic yards, metres and bags for slabs, footings, walls, stairs and columns.
- Gravel Calculator: Volume and weight of gravel for driveways, paths and bases.
- Mulch Calculator: How much mulch to cover a rectangular or round bed.
- Paint Calculator: Gallons or litres for walls and ceilings, after doors and windows.
- Flooring Calculator: Boxes of flooring to buy for any rectangular room.
- Tile Calculator: Number of tiles and boxes, with grout joints and waste.
- Fence Calculator: Panels and posts for open runs or closed loops, with gates.
- Paver Calculator: Pavers, base gravel and bedding sand for patios and paths.
- Roofing Calculator: Roof area, roofing squares and shingle bundles from building size and pitch.
- Cubic Yard Calculator: Convert area and depth to cubic yards, cubic feet, metres and litres.
- Topsoil Calculator: Cubic yards, tons and bags of topsoil for lawns and beds.
- Drywall Calculator: Sheets of drywall for walls and ceilings, minus doors and windows.
- Rebar Calculator: Bars, total length and weight of rebar for a concrete slab grid.
- Brick & Block Calculator: Number of bricks or concrete blocks for a wall, with mortar joints.
Use them on your own site
Run a blog or a contractor site? You can embed any calculator for free.
Get in touch
If a result looks wrong, or you need a calculator we don't have, tell us.