Board Foot Calculator
Convert lumber dimensions into board feet, and price the order.
Last reviewed September 19, 2026
Result
Buy 80 bd ft board feet
No allowance is added, because this is a conversion rather than an estimate. Hardwood is normally bought with 20 to 30 per cent over the finished requirement, since rough boards have to be jointed, planed and cut around defects.
- Board feet per piece
- 8 bd ft
- Total volume
- 6.6667 ft³
https://calcgallery.com/lumber-carpentry/board-foot-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use it
- Enter the thickness and width in inches, and the length in feet.
- Use the actual rough dimensions if you are buying rough sawn, and the nominal size if you are buying dimensional lumber sold that way.
- Enter how many pieces you need.
- Read the board feet, and the cubic metres if you are buying in a metric market.
How it is calculated
A board foot is a volume, and the formula is a unit conversion dressed up:
board feet = thickness (in) × width (in) × length (ft) ÷ 12
total = board feet × quantityThe twelve is there because the length is in feet while the other two are in inches. Put everything in inches and a board foot is 144 cubic inches; put everything in feet and it is one twelfth of a cubic foot. Same number either way.
Because it is a volume, thickness matters as much as face size. A 1 by 12 and a 2 by 6 of the same length are the same board footage, even though one looks twice the board.
Practical tips
Ask how the yard measures. Some price rough hardwood on the width before surfacing, some after, and some round every board up to the next inch. On a large order those conventions are worth more than the price per foot.
Board feet are not a price. They are a volume, and species and grade change the cost per board foot by a factor of ten or more. Use the footage to compare quotes for the same material, not different materials.
Measure the shortest usable length. A 10 ft board with a split in the last 18 in is an 8 ft board. Yards price by the full length, so check the ends before loading.
Buy wide boards if you need width. Gluing up a panel from narrow stock costs time and adds joints. Wide boards cost more per board foot for a reason, and sometimes that reason is worth paying.
Let it acclimatise. Lumber moves as it reaches the humidity of where it is going. A week in the shop before you cut saves a panel that cups after assembly.
With your numbers
- One piece = 2 in × 6 in × 8 ft = 8 bd ft
- Total = that × 10 pieces = 80 bd ft
Quick reference
No allowance is added, because this is a conversion rather than an estimate. Hardwood is normally bought with 20 to 30 per cent over the finished requirement, since rough boards have to be jointed, planed and cut around defects.
| Job | Board feet |
|---|---|
| 1 in × 6 in × 8 ft, 1 piece | 4 bd ft |
| 2 in × 6 in × 8 ft, 10 pieces | 80 bd ft |
| 2 in × 4 in × 8 ft, 10 pieces | 53.3333 bd ft |
| 4/4 × 8 in × 10 ft, 20 pieces | 133.3333 bd ft |
| 8/4 × 10 in × 12 ft, 5 pieces | 100 bd ft |
| 2 in × 12 in × 16 ft, 6 pieces | 192 bd ft |
| 50 × 150 mm × 2.4 m, 10 pieces | 0.18 m³ |
| 25 × 200 mm × 3 m, 20 pieces | 0.3 m³ |
Common questions
- How do you calculate board feet?
- Thickness in inches times width in inches times length in feet, divided by twelve. A 2 by 6 at 8 ft long is 2 × 6 × 8 ÷ 12, which is 8 board feet. Ten of them is 80.
- What is a board foot?
- A unit of volume equal to a piece 1 in thick, 12 in wide and 1 ft long, which is one twelfth of a cubic foot. It is a volume, not an area, so a 1 in board and a 2 in board of the same face size are not the same number of board feet.
- Do I use nominal or actual dimensions?
- Whichever the seller prices by. Softwood dimensional lumber is usually sold by the nominal size, so a 2 by 4 is charged as 2 by 4 even though it measures 1.5 by 3.5. Rough sawn hardwood is sold by actual measured size. Getting this wrong changes the answer by about a third.
- What does 4/4 or 8/4 mean?
- Thickness in quarter inches, used for rough sawn hardwood. 4/4 is one inch, 5/4 is an inch and a quarter, 8/4 is two inches. It is quoted before surfacing, so a 4/4 board planed both faces finishes closer to 13/16 in but is still sold as 4/4.
- How much extra hardwood should I buy?
- Twenty to thirty per cent over your finished requirement, and more for narrow or short parts. Rough boards have to be jointed, planed, ripped and cut around knots, splits and checks, and the yield from a rough board is never the whole board.
- How do board feet convert to cubic metres?
- One board foot is about 0.00236 m³, so roughly 424 board feet to the cubic metre. Metric mode does the conversion for you, which is useful when a supplier quotes in one and you think in the other.