This is an area calculator with a waste allowance bolted on. Describe the footprint — rectangle, L or circle — and it returns the floor area, the extra area the waste percentage adds, the total to buy, and the cost at your price per m² or ft².
The decision it supports is the pack count at the counter. Flooring is sold by the pack, and the number returned is the area you purchase, not the area you walk on. Confusing the two is how people end up one pack short halfway through a Sunday.
Measurements are taken in the selected system: metres with m² and a price per m², or feet with ft² and a price per ft².
area = length × width, which also suits a room whose alcove you fold into the overall measurement.area = (A length × A width) + (B length × B width). The plan is split into two rectangles and the parts added, so choose a split where they do not overlap or the shared strip is counted twice.area = π × (diameter ÷ 2)². The field wants the diameter, not the radius: a 5 m round room is 19.63 m², not 78.5 m².Then waste area = floor area × waste ÷ 100, total to buy = floor area + waste area, and cost = total to buy × price per unit area. Cost is charged on what you purchase, which is right: you pay for the offcuts too.
A 5.0 × 4.0 m main room with a 3.0 × 2.0 m alcove, straight-laid engineered boards at £24 per m², in packs covering 2.13 m².
| Step | Calculation | Result |
|---|---|---|
| Section A | 5.0 × 4.0 | 20.0 m² |
| Section B | 3.0 × 2.0 | 6.0 m² |
| Floor area | 20.0 + 6.0 | 26.0 m² |
| Waste at 10% | 26.0 × 0.10 | +2.6 m² |
| Total to buy | 26.0 + 2.6 | 28.6 m² |
| Estimated cost | 28.6 × £24 | £686.40 |
| Packs of 2.13 m² | 28.6 ÷ 2.13, rounded up | 14 packs |
The tool stops at 28.6 m² and leaves the pack rounding to you, because there is no field for pack coverage. Note too that 14 packs hold 29.82 m², so you keep about a square metre more than you ordered — which is what you want when a plank has to be re-cut around a badly placed radiator pipe.
Waste is not one number. The tool applies a flat percentage, so the layout judgement is yours. Straight planks in a simple room typically lose 5–10%; a room with many doorways, alcoves or a diagonal run typically 10–15%; herringbone or chevron typically 15–20%, because every cut leaves two offcuts that rarely fit anywhere else. Under-estimating waste is the commonest cause of a short order.
Direction is invisible to the tool. Boards laid along a room's long axis usually leave longer, more useful offcuts than boards laid across it, and two rooms of identical area can differ by several square metres of waste on direction alone. That judgement has to go into the waste field.
A circle is worse than πr² suggests. The area is correct, but every perimeter board is cut on a curve and the offcuts are unusable, so round floors typically want 20–30% waste rather than 10%.
Underlay is measured on the net area. You need underlay for the 26.0 m² you are covering, not the 28.6 m² you are buying; run the calculator again with waste set to zero for that figure. And remember that a pack opened for two boards cannot be returned, so round the pack count up and keep the remainder closed and dry.
Match the batch and acclimatise. Boards with the same product code but from different production runs can differ in tone, so order the whole job at once and check the batch numbers agree. Solid and engineered timber normally wants a couple of days in the room it will be laid in, packaging opened, to settle to the room's humidity; laying straight from a cold van into a warm room is a genuine route to gapping.
It handles a clean L — two rectangles joined without overlap. For a chimney breast, a bay or an angled wall, split the plan into rectangles you can measure, run each through the tool, and add the totals.
Diameter. The tool halves it before squaring, so entering a radius inflates the answer four times over.
Ten per cent for a straightforward straight lay, fifteen for an awkward room or a diagonal lay, twenty or more for herringbone, curves, or a floor full of pipework.
For the area, yes — but tiles are counted in whole pieces and bought in boxes, which is a different calculation. Use the tile calculator, which works in rows and columns.
One closed pack from the same batch, so a damaged board can be replaced years later with a matching one. It is also your insurance against a miscut during the job.