Plan a building or renovation project with free calculators for concrete, gravel, paint, tile, roofing, stairs, pools and metal stock. Each one shows its formula and a worked example, and runs in your browser.
Last updated: October 2026
Start with the floor, wall or roof area, since most estimates are area times a thickness or a coverage rate.
Area of a room or space in square feet and square meters.
Volume of a cylinder, sphere, cube, cone, or rectangular box.
Concrete, the gravel base beneath it, and the steps that lead up to it.
Concrete for slabs, footings and round columns in yd³ or m³, with bags, weight and cost.
Cubic yards, weight in tons, and bags needed for gravel, mulch, soil or stone.
Number of steps and exact riser height for a staircase.
Floors, walls and roofs, with allowances for waste and coverage.
Gallons or litres of paint for a room, with doors, windows, coats and ceiling.
Count the tiles needed for a floor or wall.
Shingles needed and estimated cost to replace a roof.
Pools, tanks and pipes, from capacity to the weight of the water inside.
Gallons or litres in a rectangular, round, oval or kidney pool, with fill time.
Tank capacity and liquid volume at any fill level.
Capacity and wall volume of a pipe from its diameter, wall thickness and length.
Weight of metal stock and solid shapes, and conversions between units.
Most home projects need several estimates that depend on each other. A patio needs a gravel base, then concrete or tiles, and sometimes steps and a coat of sealer. The calculators below follow that order, and each one explains its formula, shows a worked example and lets you switch between US and metric units.
Typical results you can reproduce with the calculators. Change the sizes to match your own project.
| Project | Result | Calculator |
|---|---|---|
| Concrete slab, 10 × 10 ft, 4 in thick | 1.23 yd³ (about 56 bags of 80 lb) | Concrete Calculator |
| Gravel base, 10 × 20 ft, 3 in deep | 1.85 yd³ (about 2.8 tons) | Gravel & Mulch Calculator |
| Paint, 12 × 12 ft room, 2 coats on the walls | about 1.9 gallons | Paint Calculator |
| Pool, 16 × 32 ft, average depth 5 ft | about 19,150 gallons | Pool Volume Calculator |
| Steel round bar, 20 mm diameter, 1 m long | about 2.47 kg | Metal Weight Calculator |
Guides that go deeper: how many bags of concrete for a slab, how much paint you need and how many gallons are in a pool.
Which calculator should I use first? Start with the Square Footage Calculator to find the area of the space, then use the material calculators (concrete, gravel, paint, tile or roofing) with that area.
How much extra material should I order? A margin of about 5 to 10% is common for waste and uneven surfaces. Tile with diagonal cuts and complicated roofs may need more.
Do the calculators work in metric units? Most of them do. The concrete, gravel, paint and pool calculators have a US and a metric option, and the Conversion Calculator handles other units.
Are the results exact? They are estimates based on the sizes you enter and typical material figures. Always follow the coverage or yield printed on your product, and check large orders with your supplier.