Flooring Calculator

How the flooring estimate works

The calculator first finds the floor area by multiplying each room length by its width, and adds a second room if you enable one, which assumes simple rectangular spaces. It then adds a waste allowance, a percentage of extra material that covers the off-cuts created when planks or tiles are trimmed to fit at walls, the inevitable breakages during handling, and a reserve for future repairs. Finally it divides this padded area by the coverage printed on each box of your chosen product and rounds the result up to the next whole box, because retailers sell flooring only in full, unopened boxes. Rounding up rather than down is essential: ordering even a fraction of a box short means stopping work to source more, often from a different production batch that no longer matches.

Planning plank rows and the last-row width

Turn on the plank planner to see how the floor lays out before you start. The number of rows is the room width divided by the plank width, rounded up, and the last-row width is whatever is left over after the full rows. This matters because a final row narrower than about a third of a plank looks awkward and is fragile to cut and click into place. The fix is to balance the layout: take the leftover width, add a full plank width, and split it between the first and last rows so both edges are a comfortable size. The planner also estimates the approximate plank count for the primary room by working out how many planks fit along the length, multiplying by the rows, and adding your waste allowance.

Costing the job: material, underlayment and labor

Switch on the cost estimate to price the whole job rather than just the flooring. You can price the flooring per unit area (per square foot or per square metre) or per box, whichever your retailer quotes, and the calculator uses the actual boxes or covered area accordingly. On top of that it adds underlayment, the foam or felt layer most floating floors need, priced per unit area, and installation labor, also per unit area, which you can set to zero for a do-it-yourself job. The cost breakdown table shows each line, its share of the total, and a grand total. It deliberately leaves out transition strips, trim, subfloor repair and delivery, so add those separately, and remember that local prices and quotes vary widely.

Choosing the right waste allowance

Waste is the single biggest variable in a flooring order, and the right figure depends on your layout and room shape. A plain rectangular room with planks laid parallel to the longest wall wastes very little, so 5 to 10% is usually enough. Diagonal or herringbone patterns generate far more off-cuts because every plank meeting a wall is cut at an angle, so allow 15% or even 20%. Rooms with many alcoves, bay windows, doorways, or angled walls also push waste higher, as does a large plank or tile size, since a small leftover strip from a big plank cannot always be reused elsewhere. When in doubt, err on the high side, the cost of one extra box is small against the disruption of running out mid-job.

Measuring irregular rooms

This tool models rectangles, but most real rooms are not perfectly rectangular. For an L-shaped or T-shaped room, split the floor into two or three rectangles, calculate each area, and add them together, or use the second-room inputs for the two halves before applying the waste allowance. For bay windows or chimney breasts, measure the largest rectangle that encloses the space and do not subtract the small protrusions, the extra material they appear to add is genuine waste you will use up in cuts anyway. Always measure each wall at floor level rather than relying on a quoted room size, because skirting boards, out-of-square corners, and plaster thickness can shift the true dimensions by several centimetres.