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Builders & DIY tools

Builders & DIY calculators guide

Material calculators reduce waste and avoid last-minute trips. Measure carefully, convert units consistently, and always add a sensible waste allowance for cuts, breakage, and pattern matching.

Measurement tips
  • Measure in one unit system (meters or feet) and convert only when needed.
  • For tiling, include a waste factor for cuts (often 5–15%).
  • For wallpaper, account for doors/windows and pattern repeat if applicable.

Tools to try

Paint Needed Calculator Flooring Boards Calculator Concrete Volume Calculator Tiling Calculator Wallpaper Calculator Unit Converter

A reliable estimating method

  1. Measure: write down dimensions and the unit (metres, millimetres, feet, inches).
  2. Normalize units: convert everything to one system before calculating (this prevents mistakes).
  3. Compute base quantity: area ÷ coverage, room area ÷ board area, or length × width × depth.
  4. Add waste: cuts, off-cuts, and breakage are normal — then round up to packaged quantities.

Worked examples (real numbers)

Example 1: paint for a room

You’re painting a wall that’s 4 metres wide by 2.4 metres high. Area = 4 × 2.4 = 9.6 m². If your paint covers 10 m² per litre and you need 2 coats: litres ≈ (9.6 ÷ 10) × 2 = 1.92 L. Round up to the nearest tin size.

Open Paint Needed
Example 2: concrete slab volume

A slab is 3 m × 2 m × 0.1 m thick. Volume = 3 × 2 × 0.1 = 0.6 m³. Concrete is often sold in bags with an approximate yield per bag — if you’re close to a boundary, add a small buffer.

Open Concrete Volume
Example 3: tiles for a floor

A floor is 3 m × 2 m = 6 m². A tile is 300 mm × 300 mm = 0.09 m². Tiles needed ≈ 6 ÷ 0.09 = 66.67 → 67 tiles. Then add waste (for example 10%) and round up to full boxes.

Open Tiling Calculator
Example 4: wallpaper coverage

Wall area is height × width. Subtract large openings (doors/windows) if it changes whether you need an extra roll. Pattern repeats and matching can increase waste — if the paper has a repeat, you often need more than a simple area calculation suggests.

Open Wallpaper Calculator

Buying advice

  • If your estimate is close to a packaging boundary (tile boxes, wallpaper rolls), round up.
  • Keep a small spare (especially tiles/boards) — batches can change and later replacements may not match perfectly.
  • Write down assumptions (units, coats, waste %) so you can re-check later.
Common inputs
Keep units consistent: tile size in the same unit as the wall/floor size. If you’re mixing millimeters and meters, convert first.