How it works
The calculator works out the flooring to buy and, for a nail-down floor, the number of fasteners.
Area to buy = Floor area × (1 + Allowance ÷ 100)
Boxes = ⌈ Area to buy ÷ Coverage per box ⌉
Board length = Floor area ÷ Board width
Fasteners = ⌈ Board length ÷ Spacing ⌉
With an average board length L: Fasteners = ⌈ Board length ÷ L ⌉ × (⌈ L ÷ Spacing ⌉ + 1)
⌈ ⌉ means rounding up. The allowance is 5 % for a straight layout and 10 % for a diagonal one, or the figure you enter.
Where the figures come from
- Allowance: the solid hardwood installation instructions of DOMA Flooring (an AHF brand, like Bruce): “5% must be added to the actual square footage needed for cutting and grading allowance (10% for diagonal installations; 10-15% for glue down installation).”
- Coverage: Bruce’s unfinished solid oak sell sheet lists 19.5 sq ft per bundle for 2-1/4 in strip and 18.5 sq ft for 3-1/4 in plank. The US example uses the 2-1/4 in strip; enter your own product’s figures.
- Fastener spacing: the NWFA Installation Guidelines’ fastener schedule – for 3/4 in solid strip less than 3 in wide, two fasteners near the ends of each piece and one every 8–10 in; for 3/4 in plank 3 in or wider, every 6–8 in.
What makes hardwood different from laminate
Solid hardwood is nailed or stapled to the subfloor through the tongue, so besides the boxes you need the right fasteners in the right number. It is also sold in random lengths with natural defects that are cut out during installation, which is why the manufacturer’s allowance includes grading as well as cutting, and it has to be acclimated to the room before it goes down. For floating floors, the laminate calculator in the related calculators covers the boxes.
Worked example in words
A 15 × 12 ft room has 180 sq ft. With the 5 % straight-lay allowance that is 189 sq ft, and at 19.5 sq ft per bundle 189 ÷ 19.5 = 9.7, so 10 bundles (195 sq ft). The floor holds 180 × 144 ÷ 2.25 = 11,520 in (960 ft) of 2-1/4 in strip; with a fastener every 8 in that is 1,440 fasteners, plus two near the ends of every board.
Worked example
Inputs
- Measure by
- Room length × width
- Room length
- 15 ft
- Room width
- 12 ft
- Layout
- Straight (5 % allowance)
- Coverage per box or bundle
- 19.5 sq ft
- Board width (face)
- 2 1/4 in
- Fastener spacing
- 8 in
Result
- Floor area
- 180 sq ft
- Area incl. allowance
- 189 sq ft
- Boxes or bundles
- 10
- Area you buy
- 195 sq ft
- Length of boards
- 960 ft
- Cleats, nails or staples
- 1,440
Common mistakes
- Ordering the bare floor area. Solid flooring has cut ends at every wall and some boards with defects that get cut out; the manufacturer’s allowance is there for that.
- Using the straight allowance for a diagonal or herringbone floor. Diagonal layouts waste more at every wall – the DOMA instructions ask for 10 % instead of 5 %.
- Counting fasteners from the room area alone. The count depends on the board width, because narrow strip has more rows per foot of room.
- Forgetting the fasteners near the board ends. Every piece gets two near its ends in addition to the regular spacing, so short boards need more fasteners.
- Installing straight from the truck. Wood flooring needs to reach the moisture conditions of the room first – follow the acclimation steps in the instructions.
Assumptions and limits
- The allowance is added to the floor area before rounding up to whole boxes or bundles.
- Board length is the floor area divided by the board’s face width.
- Without an average board length, fasteners are the board length divided by the spacing, rounded up. With it, boards = board length ÷ average length, rounded up, each with fasteners at both ends and at the spacing between them.
- Fasteners are counted for the installed floor only, not for the allowance; start and finish rows that are face-nailed are not counted separately.
- Closets, hallways and transitions are included only if you add their area.
Frequently asked questions
How many boxes of hardwood flooring do I need?
Add the cutting allowance to the floor area and divide by the coverage per box, rounding up. A 15 × 12 ft room is 180 sq ft; with 5 % added that is 189 sq ft, and at 19.5 sq ft per bundle you need 10 bundles.
How much extra hardwood flooring should I order?
AHF’s DOMA solid hardwood instructions say to add 5 % for cutting and grading, 10 % for diagonal installations and 10–15 % for glue-down installations. Your flooring’s instructions may differ.
How many flooring nails or cleats per square foot?
It depends on the board width and spacing. For 2-1/4 in strip with a fastener every 8 in, each square foot holds 144 ÷ 2.25 = 64 in of board, or 8 fasteners, plus the ones near the board ends.
How far apart should hardwood flooring nails be?
The NWFA fastener schedule asks for 3/4 in solid strip to be blind-nailed every 8–10 in with two fasteners near the ends of each piece, and 3/4 in plank 3 in or wider every 6–8 in. Thinner flooring and engineered flooring use different fasteners and spacing, and the flooring maker’s instructions come first.
Sources
- Bruce Unfinished Solid Hardwood sell sheet (WB-1492-725) — AHF, LLC (Bruce). 3/4 in solid oak in 2-1/4 and 3-1/4 in widths, lengths 8.3–84 in; "SQ FT PER BUNDLE 2-1/4˝ - 19.5, 3-1/4˝ - 18.5" (US defaults 2-1/4 in and 19.5 sq ft).
- Solid Wood Flooring 3/4" Strip and Plank Installation Instructions — DOMA Flooring (AHF, LLC). "5% must be added to the actual square footage needed for cutting and grading allowance (10% for diagonal installations; 10-15% for glue down installation)"; fastener schedule for 1-1/2 to 3-1/2 in widths: preferred spacing 8–10 in (20–25 cm).
- NWFA Installation Guidelines, Appendix F – Fastener Schedule (revised 02.2016) — National Wood Flooring Association. Solid strip 3/4 in × less than 3 in: "minimum two fasteners per piece near the ends (1”-3”). In addition, every 8”-10” apart for blind nailing"; solid plank 3 in or wider: every 6–8 in.
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 5, 2026