What next?
Floor area drives several other quantities. These are the usual next ones.
What your result means
Packs to order is rounded up, because flooring is only sold in whole packs. The spare row shows what that rounding leaves you with — anything under about half a pack is a comfortable margin for mistakes and future repairs, and more than a pack usually means the waste allowance is set higher than the room needs.
Why this one is different
Packs come whole, so the useful figures are the two either side of that: the area you will actually buy, and the spare left over once the floor is down. That spare figure is the one to keep — it tells you whether you have enough for a future repair or barely a board.
Diagonal or herringbone laying can double the offcuts
A straight lay in a simple rectangular room wastes very little — five to ten percent covers the end cuts. Lay the same boards diagonally and every row ends in an angled offcut, pushing waste to fifteen or twenty percent. Herringbone and chevron patterns go higher still.
Irregular rooms with alcoves, bay windows or a chimney breast add waste for the same reason: more edges means more cuts, and each cut leaves a piece too short to use elsewhere.
How it works
Floor area is length × width, converted to metres first. The waste allowance is added, the result divided by the coverage printed on the pack, and rounded up to the next whole pack since part packs are not sold.
How to use this calculator
- Choose your units and enter the room dimensions.
- Enter the coverage per pack from the product listing — usually around 2 m².
- Set a waste allowance: 10% for a straight lay, 15–20% for diagonal or patterned.
- Add the price per pack for a cost estimate.
Formula
Rounded up to the next whole pack. Underlay, beading and threshold strips are ordered separately.
Example calculation
A 4.5 × 3.5 m room, packs covering 2.2 m², 10% waste:
With 10% waste = 17.33 m²
17.33 ÷ 2.2 = 7.9 → 8 packs
17.6 m² bought, about 1.85 m² spare
Frequently asked questions
How much waste should I allow?＋
Ten percent for a straight lay in a rectangular room. Fifteen to twenty for diagonal lays, patterned floors, or rooms with alcoves and awkward shapes. Long, narrow rooms also waste more than square ones.
Do I need to add underlay separately?＋
Yes, unless your boards have it pre-attached. Underlay is sold by the roll in square metres — use the floor area without the waste allowance, since it is cut with far less offcut.
Should I include areas under furniture?＋
Yes. Flooring runs continuously across the room, and kitchen units are the only common exception — those are usually fitted around, though many installers still run the floor beneath for future flexibility.
Which direction should the boards run?＋
Usually along the longest wall or towards the main light source, which makes joints less visible. On timber joists, boards should run across the joists rather than along them.
Do I need an expansion gap?＋
Yes for floating floors: typically 10 to 15 mm around the whole perimeter, covered by the skirting or beading. Skipping it is the usual cause of a floor that lifts or peaks in summer.
How do I handle doorways and awkward shapes?＋
Break the room into rectangles, calculate each, and add the door threshold areas separately. Rooms with alcoves and bays are where a single length-by-width figure goes wrong.
Related calculators
Assumptions & limitations
Every figure here comes from a simplified model. Keep these limits in mind when reading your result:
- Assumes a rectangular room — measure irregular spaces as separate rectangles and add the areas.
- Pack coverage varies by product; always use the figure on the actual pack.
- Excludes underlay, beading, threshold strips and expansion gaps.
- Waste allowance is a guideline and depends heavily on the laying pattern.