Material quantity calculator
Enter your room dimensions and we'll calculate exactly how much material you need — including the correct waste allowance for your material type — with links to current pricing at major UK retailers.
Understanding waste allowances
Every material calculation should include a waste allowance — the extra material needed to account for cuts, offcuts, and breakages during installation. Getting this wrong means a trip back to the retailer mid-project, often to find that your batch is no longer available.
Why waste allowances differ by material
Tiles and plasterboard need 10% waste for standard rectangular rooms because every cut piece generates offcuts. Timber flooring and decking need 15% because the boards run in one direction and end cuts cannot be reused. Wallpaper needs 20% because each drop must be pattern-matched from the top, wasting significant paper on each roll.
Buying from the same batch
For tiles, timber flooring, and carpet, always check that all packs or rolls are from the same production batch. Batch numbers are printed on the packaging. Even the same product from a different batch can have slight colour or texture variations that are noticeable once installed.
Can I return leftover materials?
Most major retailers (B&Q, Wickes, Toolstation) accept returns of unused, unopened packs within 90 days with proof of purchase. It is worth buying one extra pack as a contingency and returning it if unused — particularly for tiles, where a future repair using the same batch is invaluable.