Understanding your result
The headline is the cartons to buy, with the floor area, the area to order (waste included) and the spare beside it. The table shows how the waste was built, the area that becomes, the cartons and what they cover, and the linear run of board those cartons contain.
The two rows that decide the order are grade and layout. Grade is a waste allowance in disguise: a select-grade board has almost no defects, so the only waste is the end cuts at the walls and the odd short piece, and 5% covers it. A character grade has knots, mineral streaks and colour variation, and the boards you reject for the middle of the room are waste too, so 10%; a rustic grade, 15%. Layout adds on top: a diagonal run cuts every board at both walls at 45°, 5 points more, and herringbone 10 points more.
Spare after the floor is laid is the flooring bought minus the room, so it includes the waste you will actually consume. If it is more than a fifth of the floor, the note says so; on a small room, whole cartons cost more than the waste does. The linear run is the figure to take to the cleats and nails calculator, since fasteners go by the foot of board, and the underlayment calculator counts the rosin paper that goes under a nailed floor.
How we calculate this
The grade allowances are the ones the waste factors reference lists for solid wood, from the NWFA installation guidelines and the major manufacturers’ own instructions. The layout extras are the same as for every other material on this site: a 45° layout wastes a triangle at both ends of every row, and herringbone wastes more because every piece is cut at an angle. The linear-feet figure assumes the whole carton is board of the nominal width, which is close enough for the fastener count. The guide to waste factors explains the reasoning, and the guide to solid, engineered and laminate floors compares the three on quantities and cost.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Carton coverage | 20 sq ft (1.86 m²) | The standard carton for 2 1/4 and 3 1/4 in strip (Bruce Dundee, Plano and Kennedale lines, 2025); plank cartons vary from 18 to 25 sq ft |
| Board width | 3 1/4 in (8 cm) | The most common strip width in current production; 2 1/4 in is the traditional size |
| Waste by grade | 5 / 10 / 15% | NWFA installation guidelines and manufacturer instructions (Bruce, Mullican, Somerset) |
| Layout extra | diagonal +5, herringbone +10 | Industry rule of thumb; see the waste factors page |
| Room | 15 × 12 ft (4.5 × 3.6 m) | A typical living room, for the example |
Assumptions last reviewed October 8, 2026.
The calculator does not know the room’s shape beyond its area, and a long narrow room laid across its width wastes more than the same area laid along it; the guide to plank direction explains why and how to decide. It does not model mixed widths or a border, and it assumes all the flooring comes from one order; mixing production runs means a colour change you can see. The hardwood cost calculator in the cost group takes the cartons from here and adds labour and finish.
Two worked examples
An 18 × 14 ft living room in select-grade 2 1/4 in oak
Straight layout, 20 sq ft cartons at $89.
- Floor area: 18 × 14 = 252 sq ft
- Waste: 5% for the grade, nothing for the layout
- Area to order: 252 × 1.05 = 265 sq ft
- Cartons: 265 ÷ 20 = 13.2, rounded up to 14 cartons (280 sq ft), $1,246
- Spare: 280 − 252 = 28 sq ft; linear run 280 ÷ (2.25 ÷ 12) = 1,493 ft of board
A select grade in a rectangular room is the best case for waste, and the fourteenth carton is mostly spare. Nearly 1,500 linear feet of narrow strip is the number that matters for the installer: at a cleat every 8 in with two near each end, that is around 2,500 fasteners, which the cleats calculator confirms.
420 sq ft of rustic 5 in hickory on the diagonal
Area typed directly, No. 2 Common grade, 24 sq ft cartons (the label says 23.5).
- Waste: 15% for the grade + 5% for the diagonal = 20%
- Area to order: 420 × 1.20 = 504 sq ft
- Cartons: 504 ÷ 23.5 = 21.4, rounded up to 22 cartons (517 sq ft)
- Spare: 517 − 420 = 97 sq ft; linear run 1,241 ft
A fifth of this order is waste, which is the honest cost of a rustic grade on the diagonal: the knots you cut out and the 45° offcuts at every wall. The wide plank also brings the NWFA’s tighter 2-point moisture rule into play, which the acclimation planner applies.
Where to find your inputs
Room or area. Wall to wall at floor level, including closets and under the doors. For an odd shape, the floor area calculator adds the rectangles.
Board width. On the carton as the nominal width (2 1/4, 3 1/4, 5 in). The actual face is slightly less; the nominal figure is what to enter.
Coverage per carton. On the carton label and the product page, in square feet. If the product is sold per bundle, use the bundle coverage.
Grade. On the product page: Clear, Select, No. 1 Common (often sold as “character” or “natural”), No. 2 Common (“rustic”, “cabin”, “tavern”).
Common mistakes
- One waste figure for every grade. Rustic grades lose three times what select grades lose. Pick the grade.
- Forgetting the layout. A diagonal adds 5 points; herringbone 10, and it usually needs a pattern product.
- Treating the carton as 20 sq ft without reading it. Plank cartons are often 18 or 23.5. The label decides.
- Buying the exact figure. Keep a carton sealed for repairs; later runs do not match.
- Mixing cartons from two orders without racking. Open several cartons and mix boards as you lay, so the colour variation spreads across the floor.
- Skipping acclimation. Solid wood must reach moisture balance with the house before it is nailed; the acclimation planner gives the days.
Questions people ask
- How many cartons of hardwood for 300 square feet?
- With 20 sq ft cartons and a No. 1 Common grade laid straight (10% waste), 300 sq ft becomes 330 sq ft, which is 16.5 cartons, so 17. A select grade at 5% needs 16 cartons; a rustic grade on the diagonal at 20% needs 18.
- What waste should I allow for hardwood flooring?
- 5% for clear and select grades in a simple room, 10% as the general figure for No. 1 Common and character grades, and 15% for No. 2 Common, rustic or cabin grades, where more boards have defects you will cut out. Add 5 points for a diagonal layout and 10 for herringbone. These follow NWFA and manufacturer guidance.
- How many square feet are in a carton of hardwood?
- Most 2 1/4 and 3 1/4 inch strip comes in 20 sq ft cartons (Bruce, for example); plank cartons run from 18 to 25 sq ft, and some wide plank is sold per bundle of 23 to 30 sq ft. The label is the only reliable figure, and it is the one this calculator asks for.
- Does board width change how much I need?
- Not the area, but it changes the number of boards and the linear feet. 200 sq ft of 2 1/4 inch strip is about 1,070 linear feet of board; the same area in 5 inch plank is 480 linear feet. Narrow strip takes more rows, more cleats and more time; wide plank takes fewer of each but moves more with humidity.
- Should I buy extra for repairs?
- One carton beyond the calculated figure is the usual advice, kept sealed and dry. Solid wood from a later production run differs in colour and sometimes in milling, and a board replaced after a leak or a dropped pan is much easier to match from the original stock.
- Does this include underlayment, nails or finish?
- No. Solid hardwood is nailed over rosin or felt paper on a wood subfloor; the underlayment calculator counts the paper and the cleats calculator the fasteners. An unfinished floor also needs sanding and finish, which the sanding and refinishing calculator covers.