Hardwood flooring calculator

How much hardwood flooring do I need for a 12 × 10 room?

Six cartons of Bruce Dundee solid oak, which come to 132 sq ft of boards. The room is 120 sq ft; with 7% extra it is 128.4 sq ft, and 128.4 ÷ 22 sq ft per carton = 5.84, rounded up to 6. That is the result the calculator opens with. Lay the boards on a diagonal and the extra rises to 15%, which makes 138 sq ft and 7 cartons.

In metric mode the default is a 3.6 m by 3 m room, 10.8 m², in Kährs Oak Nouveau engineered boards. With the same 7% that is 11.56 m², and at 2.72 m² per pack the room takes 5 packs, holding 13.6 m².

Measure the floor the boards will actually cover. Hardwood often runs through a doorway into a hall or closet, and those strips belong in the total. Include doorways, alcoves, bay windows and any adjoining area getting the same floor. For an L-shaped room or an open plan, add the rectangles and enter the sum with I know the area. Our floor measuring guide covers bays, angled walls and the rest.

How does the calculator work out cartons?

Cartons = area × (1 + extra % ÷ 100) ÷ coverage per carton, rounded up, then plus any spare cartons you ask for. Wood flooring is sold in cartons or packs with a stated coverage, and that coverage depends on the board width and the lengths packed, so it is different for every product line. The calculator holds three presets from manufacturer data and accepts any other figure from the label.

Worked example: Bruce Dundee, straight lay, one spare

12 ft × 10 ft = 120 sq ft. Add 7%: 120 × 1.07 = 128.4 sq ft. Bruce Dundee solid oak (3/4 x 3-1/4 in) covers 22 sq ft (2.04 m2) per carton. 128.4 ÷ 22 = 5.84, rounded up to 6 cartons for the floor. With one spare carton for repairs, the order is 7 cartons, or 154 sq ft. A roll of Aquabar B covers 500 sq ft per roll, so one roll does the room.

Worked example: a 500 sq ft floor in Bruce D35

500 × 1.07 = 535 sq ft. Bruce unfinished solid strip D35 (3/4 x 3-1/4 in) covers 18.5 sq ft (1.72 m2) per carton. 535 ÷ 18.5 = 28.9, rounded up to 29 cartons, which hold 536.5 sq ft. Both Bruce products use the same board size, but the D35 carton holds less, so the same floor needs more cartons. That is why the carton figure matters more than the board size printed on the box end.

How much extra hardwood should I buy?

Mullican Flooring adds 5–7% for a standard install and 10–15% on a diagonal, with more for character and builder grades (Mullican Flooring). The calculator takes the top of each range, since running short on a wood floor is worse than having a few boards left: a later carton may come from a different production run and may not match. Mullican's own text gives the lower figure for a standard floor, so if your room is a simple rectangle you can type 5 into Extra to order.

Sources disagree. Ted Todd, a UK wood flooring maker, uses a higher figure than Mullican in its worked example, and no NWFA waste percentage was found in the guidelines retrieved. The UK carbon-accounting default is higher too. RICS (2023) gives a default site waste rate of 10% for timber floor boards and aggregate, against 2% for structural timber frames and 1% for glass. That RICS figure is meant for estimating waste on whole building projects, not for one room, but it shows that the professional default for timber boards sits above Mullican's straight-lay figure.

A frequent assumption is that hardwood needs the same allowance as laminate. Pergo asks 10% for laminate; Mullican asks less for wood. A likely reason is the boards: solid strip flooring is packed in random lengths, so a short offcut can often start the next row. Character grades are the exception, since boards with large knots or splits get cut out. Mullican does not put a number on that, and no source quantified the extra for random-length boards, so raise the figure yourself for a rustic grade.

Why keep spare cartons of hardwood?

For repairs years later. Mullican suggests buying 1-2 extra cartons to keep for future repairs. A gouged or water-stained board can be cut out and replaced, but only with a board that matches in species, grade, width, finish and colour, and the same product bought later can differ in tone. The Extra cartons to keep box adds spares after the floor's own count is rounded, so they are separate from the waste allowance rather than hidden inside it. It starts at zero; set it to one or two.

Store the spares flat, in the house, not in a damp garage or shed, so they stay at the same moisture content as the installed floor.

Illustration sources

• Mullican Flooring — How to Calculate the Correct Footage When Purchasing Hardwood Flooring

Does solid or engineered wood change the count?

Not the count, only the details around it. The carton sum is the same for both: area, extra, carton coverage. What changes is the coverage per carton, because engineered boards are often wider and longer and come in metric packs, and the gap you leave at the walls.

For solid wood that is nailed down, the result gives NWFA's expansion space. NWFA (2007): leave about 3/4 in expansion space at walls and vertical obstructions for nail-down solid flooring. Those are the 2007 guidelines, the edition that could be retrieved, so check the current NWFA guidance and the board maker's instructions before you set spacers. For engineered flooring, whether glued, nailed or floating, the calculator tells you to follow the maker's figure, since engineered products set their own.

Underlayment follows the same split. Solid boards nailed over a wood subfloor can go over a hardwood underlayment such as Aquabar B; a floating engineered floor uses the underlayment its maker names. Choose None or not needed if the boards are glued straight to the subfloor.

When can I install hardwood after it is delivered?

When the wood and the subfloor are close enough in moisture content, not after a set number of days. NWFA: some manufacturers do not require acclimation; follow the flooring maker's instructions and MC readings, not a fixed day count. The common belief that every wood floor must sit for a fixed time before installing is what the NWFA guidance corrects. The guidelines set the moisture targets instead:

• NWFA: solid strip flooring (under 3 in wide) should be within 4% moisture content of the subfloor.
• NWFA: solid flooring 3 in or wider should be within 2% moisture content of the subfloor.
• NWFA: run permanent heating/air conditioning at least 5 days before installation where codes allow.
• NWFA: check moisture on about 40 boards per 1,000 sq ft delivered.

For a floor the size of the default room, that sampling rule means checking a handful of boards from different cartons rather than one. A pin-type or pinless moisture meter does the job; read the subfloor too. All four figures come from the NWFA's 2007 guidelines, the edition retrieved for this page.

What changes for metric, UK and European wood floors?

Units and packs. In metric mode, enter the room in metres; the result is in square metres, the carton preset is the Kährs pack, and the expansion space converts to 19 mm. European engineered boards are sized in millimetres and sold by the pack in square metres. Kährs Oak Nouveau engineered boards (15 x 187 x 2420 mm) come 2.72 m2 (29.3 sq ft) to a pack. For another brand, choose Other flooring and type the m² per pack.

UK makers measure in metres throughout. Record every dimension in one unit (Ted Todd uses metres) so areas add correctly. Ted Todd's worked example also uses a larger allowance than Mullican's US figure, in line with the RICS default of 10% for timber boards, so a UK fitter quoting that much is not padding the order. Type 10 into the extra box to match.

Underlayment is the one preset sold only in US units, as a 500 sq ft roll. In metric mode the calculator converts it to square metres; for a European underlay, choose Other underlayment and enter its m² per roll.

When is the carton count wrong or not enough?

• Patterns. Herringbone, chevron and parquet use different products and much more cutting than the straight and diagonal lays Mullican's figures cover. Use the pattern maker's figure.
• Borders and inlays. A picture-frame border or a feature strip has its own cuts at every corner. Count it separately.
• Stairs. Treads, risers and stair nosing are sold by the piece. Count them by the step.
• Character and rustic grades. More boards get culled for defects; Mullican says to allow more without a figure, so raise the extra.
• Reducers, thresholds and trim. These are bought by the length and are not in the result.
• Subfloor work. Sheathing, levelling and moisture barriers over concrete are separate jobs with their own quantities.

The rounding can also mislead on small jobs. A closet of 20 sq ft still needs a whole carton, and the result will show far more extra than the percentage suggests. That is the carton size, not a mistake.

How much wood goes to waste on US building sites?

A great deal. EPA estimates 3.4 million tons of wood products were wasted during US construction in 2018, out of 40.8 million tons of wood in all C&D debris. Those are EPA's latest national figures of their kind, and they cover all wood products on construction and demolition sites, from framing to flooring, not floors alone. They are a reminder that a waste allowance is real material, and that a good measurement keeps it from growing.

Floors are a common project. About 5.47 million US homeowners reported carpeting, flooring, paneling or ceiling-tile projects in 2023, totalling about $25.0 billion (Harvard JCHS Table A-1, 2023 AHS). The Harvard category groups wood floors with carpet, paneling and ceiling tile, so it is not a hardwood count. For wider figures on C&D debris figures by material, see our statistics page.

Which calculator do I need next?

Hardwood rarely runs through every room. For a wood-look floor in a basement or a rental, the laminate calculator gives laminate packs needed with Pergo's allowance. Bedrooms off the same hall may get carpet; the carpet calculator handles roll widths and seams. To weigh wood against the other options first, read the floor material comparison.

The full set is on the flooring calculator hub, and our waste allowances by material guide puts the wood figures beside tile, laminate and carpet.

Hardwood flooring calculator questions

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