Flooring Calculator — Packs, Waste & Underlay
Calculate flooring packs for parquet, laminate, LVP or engineered wood. Enter room dimensions and board size, choose your installation pattern, and get the number of packs with waste factor, underlay and skirting board lengths.
How many packs or boxes of flooring do I need?
Add waste to the room area first — 5–7% for a straight lay, 10–15% for diagonal or herringbone — then divide by the coverage printed on the pack, usually somewhere near 2 m² or 20 sq ft. Round up to whole packs, and keep the offcuts until the job is signed off.
How much underlay do I need?
The same area as the floor, plus about 10% for overlaps and trimming. Rolls commonly hold 10–15 m² (110–160 sq ft), so a 20 m² or 215 sq ft room takes two. Over a concrete subfloor you also need a damp-proof membrane — either built into the underlay or laid separately beneath it.
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How the flooring calculator works
- 1Room area = length × width (m²)
- 2Waste factor: straight lay 5–7%, diagonal or herringbone 10–15%
- 3Pack count: area with waste ÷ coverage per pack (from product label)
- 4Underlay: same area as flooring, plus 10% for overlaps and waste
- 5Skirting boards: room perimeter − door widths, with 10% extra for mitres
- 6Round all quantities up to nearest whole pack
Worked example
Living room: 5 × 4 m = 20 m² (16 × 13 ft, 215 sq ft). Laminate in straight lay (7% waste). Packs cover 2.13 m² — 22.9 sq ft — each.
Area with waste: 21.4 m² (230 sq ft). You need 11 packs of laminate, 22 m² (237 sq ft) of underlay, and approximately 16.5 lm — 54 linear feet — of skirting board.
Frequently asked questions
How much extra flooring should I buy?
Straight lay: 5–7% waste. Diagonal or herringbone pattern: 10–15%. Always buy one extra pack — colour and batch variations make it nearly impossible to match exactly later.
Do I need underlay for laminate flooring?
Yes — most laminate requires 2–3 mm underlay, about ⅛ in, for cushioning, moisture protection and acoustic damping. Some laminate comes with underlay pre-attached. Check the product specification before buying separately.
How many packs of flooring do I need for a 20 m² room?
This depends on the pack coverage. A typical 2.13 m² (22.9 sq ft) pack: 11 packs with 7% waste. A 1.99 m² (21.4 sq ft) pack: 11–12 packs. Always check the pack size on the product label and use the calculator above.
What is the difference between laminate and LVP flooring?
Laminate has a wood-fibre core and is not waterproof — avoid in bathrooms and kitchens. LVP (Luxury Vinyl Plank) is 100% waterproof with a rigid or flexible plastic core — ideal for wet areas and underfloor heating.
Can I install flooring over underfloor heating?
Most laminate and LVP is compatible with underfloor heating up to 27°C — 80°F — surface temperature. Check the product's thermal resistance — it should be below 0.15 m²K/W, about R-0.85 in US units. Solid hardwood is generally not recommended.
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