What this calculator works out
Flooring is bought in whole packs, not by the square metre, so the real question isn't the floor area but how many packs that turns into once wastage and box rounding are added. This calculator takes your room's size, a flooring type (laminate, LVT or click vinyl, or engineered wood) with its pack coverage, and a wastage allowance, and works out the packs to buy. It extends the same list to underlay rolls, beading lengths and door bars, with an optional cost per item added into one total. Every measurement carries its own metric or imperial toggle.
How the maths works
Start from the floor area, typed directly or worked out from length times width. Add the wastage allowance, then divide by the pack's coverage and round up, since a supplier can't sell part of a pack.
Underlay is worked out against the bare floor area, without the flooring's own wastage percentage, since a roll trims down at the edges rather than being cut into small off-cuts the way patterned plank layouts are.
Beading runs the room's perimeter, twice the length plus twice the width, unless you enter a length directly for doorways or walls that won't get any. That length rounds up into whole 2.4m pieces, the common length beading and scotia trim is sold in.
A worked example
Take a 4m by 3.5m UK room, 14 m², fitting laminate at this calculator's 2.5 m² per pack default with 5% straight-lay wastage. 14 × 1.05 = 14.7 m², ÷ 2.5 = 5.88, rounded up to 6 packs (15 m² bought). Underlay at 15 m² a roll: 14 ÷ 15 = 0.93, rounded up to 1 roll. The perimeter is 2 × (4 + 3.5) = 15m, ÷ 2.4 = 6.25, rounded up to 7 beading pieces (16.8m bought). With one door bar, and rough UK prices of £18 a pack, £22 a roll of underlay, £4 a beading length and £9 a door bar, materials come to (6×18) + (1×22) + (7×4) + (1×9) = £167, before adhesive, tools or delivery.
The American equivalent: a 12ft by 14ft room, 168 sq ft, fitting LVT at a 20.1 sq ft per case default (Home Depot's LifeProof click-lock plank) with the same 5% wastage. 168 × 1.05 = 176.4 sq ft, ÷ 20.1 = 8.78, rounded up to 9 cases. Underlay at 100 sq ft a roll: 168 ÷ 100 = 1.68, rounded up to 2 rolls. The perimeter is 52ft, about 15.85m, ÷ 2.4m is 6.6, rounded up to 7 lengths of trim. With one transition strip, and rough US prices of $45 a case, $16 a roll of underlay, $12 a length of trim and $15 a strip, materials come to (9×45) + (2×16) + (7×12) + (1×15) = $536, again before adhesive or delivery.
Choosing a flooring type and pack coverage
Laminate is a printed decorative layer over a fibreboard core, click-fitted without glue or nails, and generally the cheapest of the three. B&Q's own laminate lines include options around 2.5 m² a pack, this calculator's default, up to nearly 3 m² for some styles; Pergo's laminate at Home Depot commonly ships in cases around 19.6 sq ft, roughly 1.8 m² converted.
LVT (luxury vinyl tile) and click vinyl are a fully synthetic plank or tile, more tolerant of damp than laminate and often sold as waterproof. Wickes' Novocore covers 1.98 m² a pack, this calculator's LVT default; Home Depot's LifeProof click-lock plank covers 20.1 sq ft, about 1.87 m², a close match.
Engineered wood is a real hardwood veneer bonded over a plywood or HDF core, giving the look of solid wood with more stability. Wickes' W by Woodpecker ranges run 1.08-1.5 m² a pack depending on plank width, with 1.5 m² used here as the default; US engineered cartons commonly run larger, often 20-30 sq ft.
Solid wood is deliberately left out of the pack model above. It's usually sold and priced by length or by the board, and typically nailed, screwed or glued rather than click-fitted, so a supplier's own board count is the reliable source for that job.
Wastage: straight lay or diagonal and herringbone
A straightforward rectangular room, boards running wall to wall, typically only needs about 5% extra for trimmed edges and the odd damaged plank. Cutting on the diagonal, or laying herringbone or chevron, uses noticeably more, since every plank meets an angled cut and far fewer off-cuts can be reused. Published trade guidance for herringbone and chevron commonly runs 10-15%, so this calculator's 10% option sits at the lower end of that range; raise it by hand, or buy an extra pack, on a large or complex herringbone room, or one with a lot of alcoves and thresholds to cut around.
Underlay, and when you need a vapour barrier
Underlay cushions the floor underfoot, deadens impact sound between floors, and on some products carries a built-in damp-proof membrane. UK rolls commonly cover 10-15 m² each; Wickes' own 3mm foam underlay with an integrated moisture barrier covers 15 m² a roll, this calculator's default. US rolls are usually sold in larger square footage instead, Home Depot's combined underlay-and-vapour-barrier products commonly run around 100 sq ft a roll.
A vapour barrier, sometimes a separate polythene sheet and sometimes built into the underlay, is worth treating as compulsory over solid concrete or screed, since residual moisture can keep travelling up through a slab long after it looks dry. A suspended timber subfloor with a ventilated void usually doesn't need one. Always check the flooring manufacturer's own fitting instructions too, since some click floors, particularly certain LVT ranges, specify their own underlay or none at all.
Expansion gaps around the edge
Laminate, LVT and engineered wood all move slightly indoors with temperature and humidity, expanding through a warm, humid summer and contracting back over a dry winter. Manufacturers commonly ask for a gap of around 8-12mm around the room's full perimeter, against every wall, doorway, pipe and fitted unit, later hidden by skirting or the beading counted above. Skip that gap and a floor with nowhere to expand can bow, peak along a joint (fitters call this "tenting"), or push against a door lining, none of which shows on day one. A long or wide run, especially open-plan, sometimes needs the gap widened further, occasionally with a mid-floor strip; the flooring's own fitting instructions give the figure that should win over any general rule.
Which direction to lay flooring
There's no single rule that always wins, but a few things usually decide it. Running boards the same way as the room's main light source, typically parallel to the wall with the largest window, makes joints less visible since they catch less cross-light. Running boards along a room's length rather than its width tends to make it look longer, with fewer end-to-end joins along the direction most people walk. Through an open-plan space, keeping one direction throughout looks more deliberate than switching at every doorway. Where none of that applies, running boards away from the main entrance is a reasonable fallback.
Acclimatising flooring before you fit it
Laminate, LVT and especially engineered wood should sit in the room they're going into, still in their sealed packs, for a set period before fitting, commonly 48 hours and sometimes longer for thicker engineered boards, so the material settles to that room's actual temperature and humidity rather than a warehouse or delivery van's. Skipping this is a common cause of gaps opening up, or boards peaking at their joints, weeks after a job that looked perfect on day one. Store packs flat rather than on end, and keep the room at its normal lived-in temperature, since acclimatising in a cold room before fitting into a warm one doesn't achieve much. Always check the product's own stated acclimatisation time rather than assuming 48 hours covers every case.
Questions people ask
How many packs of flooring do I need?
Add your wastage allowance to the floor area, divide by the pack's coverage and round up. A 14 m² room in 2.5 m² packs with 5% wastage is 14.7 m² divided by 2.5, rounding up to 6 packs.
Which direction should I lay flooring?
Parallel to the room's main light source usually hides the joints best, and running boards along a room's length rather than its width tends to make it look longer. In an open-plan space, keeping one direction throughout looks more deliberate than switching at every doorway.
Do I need to acclimatise flooring before fitting it?
Yes, commonly 48 hours in the room it's going into, still in its sealed packs, so it settles to that room's temperature and humidity. Skipping this is a common cause of gaps or peaking joints appearing weeks after fitting.
What underlay should I use, and when do I need a vapour barrier?
UK rolls commonly cover 10-15 m² and US rolls around 100 sq ft, often with a built-in moisture barrier. Treat one as compulsory over solid concrete or screed, since moisture can keep travelling up through a slab long after it looks dry; a ventilated timber subfloor usually doesn't need one.
Why do I need an expansion gap around the edge?
Laminate, LVT and engineered wood all move slightly with temperature and humidity indoors. A gap of around 8-12mm around the perimeter, hidden by skirting or beading, gives that movement somewhere to go without the floor bowing or peaking at the joints.
Can I use this calculator for solid wood flooring?
Not directly. Solid wood is usually sold and priced by length or by the board rather than a fixed-coverage pack, and typically nailed, screwed or glued down rather than click-fitted, so a supplier's own board count is the more reliable source for that job.
Pack coverages are checked against current listings at B&Q and Wickes for the UK, and Home Depot (Pergo, LifeProof) for the US. Underlay coverages follow Wickes' and Home Depot's own roll listings; beading length follows the common 2.4m trade length sold by UK flooring trim suppliers. Wastage guidance for herringbone and chevron follows commonly published trade figures. Real figures vary by supplier, so treat this as a planning estimate, round up when buying, and check the manufacturer's own fitting instructions for acclimatisation, underlay and expansion gaps.