This page opens with an L-shaped room already split in two, in metres: a 5 × 4 m main part and a 3 × 2.5 m leg. Each part is one Area in the calculator; the total floor, the waste and the boxes are worked out for both together. Replace the sizes with your own, add a third area for a T-shape or a hallway, or remove one.
Splitting a room into rectangles
The calculator multiplies length by width, so every part you enter has to be a rectangle. Sketch the room on paper first and draw straight lines from the inside corners until every piece is a rectangle, then measure those pieces, wall to wall at floor level.
| Room shape | Split into | Floor area |
|---|---|---|
| L-shape | 5 × 4 m and 3 × 2.5 m | 20 + 7.5 = 27.5 m² |
| T-shape | 6 × 3 m across the top, 2 × 3 m stem | 18 + 6 = 24 m² |
| 4 × 4 m room with a 1 m × 40 cm chimney breast | 4 × 3.6 m and 3 × 0.4 m beside the breast | 14.4 + 1.2 = 15.6 m² |
| Room with a bay | the room, and the bay as the rectangle around it | room + bay box |
The last two rows show the two tricks: leave out what the floor won’t cover by splitting around it, and treat a curve or an angle as the rectangle that contains it.
Why odd shapes need more extra
Every inside corner and every angled wall means cuts, and an offcut from one corner rarely fits the next. Quick-Step plans 5% extra for a regular room and 10% for difficult rooms; Pergo says the same 5% for a standard room and up to 10% for a small room with tricky areas. The waste box starts laminate at 10%: for an L-shape that’s usually right, for a room with several notches, angles and pipes go higher.
Both makers also ask for an expansion gap at every wall, threshold and pipe (Quick-Step 8 to 10 mm, Pergo 10 mm), which skirting or trims cover. Don’t take the gap off your measurements: the boards that go to the wall are cut anyway.
Sources
Quick-Step UK, “How much floor do I need for my room?”, and Pergo, “How much flooring is required for my space?”, both read in October 2026.