Building calculators
Quick metric estimates for DIY and trade jobs: how much concrete, plaster, screed, flooring or paint to order. Type your measurements and the answer updates as you go.
Materials
- Concrete calculatorEnter the length and width in metres and the depth in millimetres to get the volume in m³ and the number of 25kg bags of ready-mix.
- Plaster calculatorEnter the wall or ceiling area in m² and the coat thickness in mm to see how many 25kg bags of multi-finish to buy.
- Screed calculatorEnter the floor area in m² and the screed depth in mm to get the volume, the weight in tonnes and how much sand and cement a 4:1 mix needs.
- Flooring calculatorEnter the room area in m², the coverage of one pack in m² (printed on the box) and a wastage allowance to see how many packs to buy.
- Paint calculatorEnter the wall area in m², the number of coats, the coverage per litre and any doors and windows to deduct, and see the litres and tins to buy.
- Brick and block calculatorEnter the wall length and height in metres, deduct any openings, pick the wall type and see how many bricks or blocks to order.
- Plasterboard calculatorEnter the wall or ceiling area in m², pick a sheet size, set the number of layers and see how many sheets to buy.
- Tile calculatorEnter the area in m², the tile size and joint width in mm, and see the tiles, adhesive and grout to buy.
- Aggregate calculatorEnter the length and width in metres and the depth in millimetres, pick a material, and see the volume in m³ and the weight in tonnes.
- Paving calculatorEnter the patio area in m², pick a slab size and joint width, and see how many slabs and how much Type 1 sub-base to order.
Heating and decorating
- Radiator BTU calculatorEnter the room size in metres, pick the room type, glazing, insulation and external walls, and see the heat output you need in watts, BTU/h and kW.
- Wallpaper calculatorEnter the room length, width and wall height in metres, plus the pattern repeat and roll size, to see how many strips and rolls you need.
- Insulation calculatorEnter the area in m², the coverage per board, roll or pack printed on the label, the number of layers and a wastage allowance.
Garden
- Fencing calculatorEnter the fence length in metres, the panel width and the post width to see how many panels, posts and gravel boards a straight run needs.
- Decking calculatorEnter the deck length and width in metres, the board width and gap in mm, the stock board length and joist spacing, and see the boards and joists to order.
Frequently asked questions
Are these calculators exact?
No. They are estimates, and you should check the manufacturer's coverage rates before you order.
What units do the calculators use?
Metric: metres and millimetres for sizes, m² for areas, m³ for volumes, kg and tonnes for weights, and litres for paint.
Do the results include wastage?
Yes, each calculator has an allowance or wastage box you can change. Bags, packs and tins are always rounded up to whole units.