Flooring Calculator

How to use this calculator

1. Measure the room wall to wall at the widest points.
2. For L-shaped rooms, add the second rectangle under Advanced options.
3. Choose the layout; diagonal and herringbone create more offcuts.
4. Enter the coverage per box exactly as printed on the carton.
5. Use the underlay and baseboard lines in the shopping list as a starting point.

Method & assumptions

Area = Length × Width (+ extra rectangles)
Boxes = Area × (1 + waste %) ÷ coverage per box, rounded up

Coverage per box

sq ft or m² printed on the carton

Waste %

offcuts and defects; depends on layout

Assumptions & limits

• Area includes closets and doorways you plan to floor.
• Baseboard length is the room perimeter — subtract door widths yourself.
• Underlay is estimated at area + 5% overlap.

Rounding: purchase quantities are always rounded up to whole bags, boxes, sheets or bundles. See our methodology.

Worked examples

In depth: flooring planning notes

Measuring rooms that are not rectangles

Most rooms are not perfect rectangles. The easiest way to measure an L-shaped or T-shaped room is to split it into rectangles, measure each and add the areas. Include closets and alcoves that will be floored, and measure into door openings to the middle of the threshold. Measure at floor level, not along a skirting board that may be out of line, and round each measurement up to the nearest inch or centimetre.

Our flooring calculator handles a single rectangle; for complex rooms, use the square-footage calculator for each part and enter the total area. Write the numbers down on a sketch — you will need them again for underlay and trim.

Waste, acclimatisation and buying the right number of boxes

Laminate and vinyl plank come in boxes with coverage printed on the end, for example 19.8 sq ft or 2.22 m². Divide the floor area plus waste by that figure and round up. Straight installations in a simple room usually need 5–7% extra; rooms with many corners, door frames and pipes need 10%, and diagonal or herringbone layouts 15% or more. Engineered and solid hardwood vary more board-to-board, so allow extra to cull defects.

Many floors must acclimatise in the room before installation — often 24–48 hours with the boxes flat and opened at the ends. Check the manufacturer's guidance, and leave the expansion gap they specify at every wall; skirting or quarter-round covers it.

Underlay is sold in rolls by area, and skirting or baseboard by length. The calculator estimates skirting from the room perimeter minus door openings, so you can order it at the same time. Keep one unopened box after the job: matching a discontinued floor later is very hard.

Subfloor preparation and extras

The subfloor must be flat, clean and dry before any floating floor goes down. Many manufacturers specify a maximum deviation, such as about 3/16 in over 10 ft (or 3–5 mm over 2 m). Self-levelling compound fills hollows on concrete; high spots are ground or sanded. Concrete slabs usually need a vapour barrier unless the underlay includes one.

Plan the extras at the same time as the boxes: underlay rolls, transition strips at doorways, stair nosings, door-frame undercut tools and spacers for the expansion gap. Ordering everything together avoids a second trip that stalls the job halfway through a room.

Tips & common mistakes

• Open boxes from several cartons and mix planks to avoid patches of one shade.
• Keep one spare box for future repairs.
• Remember the expansion gap at walls — it is hidden by the baseboard.

Sources

1. National Wood Flooring Association – installation guidelines — checked 2026-10; verify before launch
2. Pergo – installation instructions — checked 2026-10; verify before launch
3. NIST – unit conversion factors — checked 2026-10; verify before launch

Default values (bag yields, coverage rates, densities) are typical figures from manufacturer literature. Always check the label on the product you buy.

Cite or embed this calculator

DIYCalcLab. “Flooring Calculator.” Oct 18, 2026. https://diycalclab.com/flooring/flooring-calculator/

An embeddable version for blogs and contractor sites is planned.