Board Feet and Lumber Order Calculator
Board feet for a list of parts, exactly and as the yard will tally them, with a waste allowance and a price per board foot, so you know what to ask for and what it will cost.
- Order
- 16.00 board feet of parts as tallied, 20% waste, 20 board feet to buy
The parts
exactly, and as the yard will count them| Part | Qty | Size | Board feet | Tallied | Cost |
|---|---|---|---|---|---|
| Top | 1 | 4/4 × 24" × 48" | 8.00 | 8.00 | — |
| Legs | 4 | 8/4 × 2 1/2" × 29" | 4.03 | 4.00 | — |
| Aprons | 4 | 4/4 × 4" × 40" | 4.44 | 4.00 | — |
The order
what to ask for| What | Board feet |
|---|---|
| The parts, measured | 16.47 |
| The parts, as tallied | 16.00 |
| Waste at 20% | 4.00 |
| To buy | 20.00 |
| To ask for | 20 |
How this is worked out
A board foot is a foot long, a foot wide and an inch thick: 144 cubic inches. A part's board feet is its thickness in inches times its width in inches times its length in inches, over 144. Thickness is the rough size in quarters, because that is what you buy; the part may finish at 3/4" but it came out of a 4/4 board, and the yard charges for the 4/4.
The yard does not measure to the sixteenth. Under the hardwood rules it charges nothing thinner than 4/4, takes width to the nearest inch, and takes length down to the whole foot. So the calculator shows two figures: the parts measured exactly, and the parts as they will be tallied. In the example on this page the parts measure 16.47 board feet and tally at 16.00.
Waste is the part that trips people up. Jointing, planing, squaring ends, cutting around defects and matching grain all eat wood, and the allowance is a share of what you buy, not a markup on the parts: to have 20% for waste you divide by 0.8, not multiply by 1.2. Twenty to thirty percent is usual for rough hardwood; the example, at 20%, comes to 20.0 board feet to buy.
How to use it
- List the parts: what it is, how many, the rough thickness, and the width and length as you would cut them. Fractions are fine.
- Set the waste allowance, and a price per board foot if you know it.
- Read the board feet to buy, and the two totals under it: what the parts measure, and what the yard will count. Ask for the tallied figure plus waste; the difference is real.
- Print the order and take it with you.
What it assumes
- A board foot is 144 cubic inches: a foot long, a foot wide, an inch thick. Thickness is the rough size in quarters, which is what the yard charges for, not what the part finishes at.
- The tallied figure follows the hardwood rules as yards apply them: nothing thinner than 4/4 is charged as less than 4/4, width goes to the nearest inch, length goes down to the whole foot. Widths on the half inch alternate up and down under the rules; here they go up.
- The waste allowance is a share of what is bought, not a markup on the parts: 20% waste means buying the parts divided by 0.8. Twenty to thirty percent is usual for rough hardwood; more for figured wood, grain matching or a first project.
- The parts listed are the parts wanted. Which boards to buy to yield them, and how to lay them out, is a different problem.
Sources
- Grading sawn lumber: measurement. Board foot and surface measure defined, thickness in quarters, and the tally rounding of widths and lengths — American Hardwood Export Council (checked 2026-09-28)
- Calculating waste from rough lumber: allowances of 20 to 30 percent and up, and why the allowance divides rather than adds — WOODWEB knowledge base (checked 2026-09-28)