The Unit Lumber Yards Quote You By — In Plain Language
Lumber yards don’t price wood by the piece the way hardware stores do. They quote hardwood by the board foot — a volume unit equal to a 12″ × 12″ × 1″ block of wood (144 cubic inches). If your cut list has four different board sizes, converting each one by hand is slow and error-prone.
This free board foot calculator handles multiple board sizes at once: add a row per board dimension, set a quantity for each, and get a per-board breakdown, the grand total, and an estimated cost if you enter the price per board foot.
Lumber · board feet · cost estimate
Every board row needs a positive thickness, width, length, and quantity. Please check the highlighted rows.
Total lumber volume
Across all your boards
How to Use This Calculator
- Enter a board’s dimensions — thickness in inches, width in inches, length in feet, and how many identical boards you need.
- Click “+ Add another board” — add a row for every different board size in your cut list.
- (Optional) Enter price per board foot — what your supplier charges, for an instant cost estimate.
- Click “Calculate Board Feet” — you get total board feet, a per-board breakdown table, the cost estimate, and every step of the math.
The Board Foot Formula
Because a board foot is 144 cubic inches (12″ × 12″ × 1″), and length is measured in feet, the standard formula is:
Worked example
You’re building a bookshelf and need three boards, each 1 inch thick × 10 inches wide × 7 feet long, with oak priced at $6.50 per board foot:
- Per board: (1 × 10 × 7) ÷ 12 = 70 ÷ 12 = 5.83 board feet
- Total: 5.83 × 3 = 17.50 board feet
- Cost: 17.50 × $6.50 = $113.75
That’s the entire calculation — and the calculator repeats it for as many different board sizes as your project needs.
Quick Reference: Common Board Sizes
Board feet per single board at popular sizes (using actual full inches):
| Size | Board feet per board |
|---|---|
| 1″ × 6″ × 8 ft | 4.00 bf |
| 1″ × 8″ × 8 ft | 5.33 bf |
| 1″ × 10″ × 8 ft | 6.67 bf |
| 2″ × 6″ × 8 ft | 8.00 bf |
| 2″ × 8″ × 10 ft | 13.33 bf |
| 2″ × 10″ × 12 ft | 20.00 bf |
The Nominal vs. Actual Trap
Here’s the mistake that ruins half of all board-foot calculations: a “2×4” is not 2 inches by 4 inches. Nominal lumber sizes name the rough-sawn piece; the board you actually buy is planed smaller.
| Nominal size | Actual size | 8-ft board, board feet (actual) |
|---|---|---|
| 1×6 | 0.75″ × 5.5″ | 2.75 bf |
| 2×4 | 1.5″ × 3.5″ | 3.50 bf |
| 2×6 | 1.5″ × 5.5″ | 5.50 bf |
| 2×8 | 1.5″ × 7.25″ | 7.25 bf |
Always enter actual measured dimensions in the calculator. Hardwood from a real lumber yard is usually sold at true rough dimensions (a 4/4 board is a full 1 inch), so ask the yard how they measure.
Tips for Buying Lumber by the Board Foot
- Compare yards apples-to-apples — a $3/bf price on walnut is the only fair way to compare two suppliers selling different board sizes.
- Add 10–15% waste — planing, ripping, and defects eat volume. Order a little more board footage than your cut list totals.
- Watch the thickness grading — hardwood is often sold as 4/4 (1″), 5/4 (1.25″), 6/4 (1.5″) or 8/4 (2″). Thicker stock is priced higher per board foot.
- Live-edge slabs need average width — measure the width at several points, average them, and use that average in the calculator.
- Confirm who’s rounding — some yards round board footage up per piece. Knowing your own exact total (from the calculator) keeps the invoice honest.
Frequently Asked Questions
What is a board foot?
A board foot is a unit of lumber volume equal to a block of wood 12 inches × 12 inches × 1 inch — 144 cubic inches. One cubic foot of wood contains exactly 12 board feet.
How do you calculate board feet?
Multiply thickness (inches) × width (inches) × length (feet), then divide by 12. For example, a 2″ × 6″ × 8 ft board is (2 × 6 × 8) ÷ 12 = 8 board feet.
Why divide by 12 in the board foot formula?
The division by 12 converts the mixed units: thickness and width are in inches, length in feet. It comes from the definition — 1 inch thick × 12 inches wide × 1 foot long is exactly one board foot.
How many board feet do I need for my project?
List every board size in your cut list, calculate board feet for each (thickness × width × length ÷ 12), multiply by quantity, and sum them all. This calculator does exactly that, plus a cost estimate.
What’s the difference between board feet and linear feet?
A linear foot measures only length — one foot of board, regardless of width or thickness. A board foot measures volume. A 12-foot 1×6 is 12 linear feet no matter its width or thickness — but exactly 6 board feet once volume is counted.
How much does a board foot cost?
It depends on the species: common pine runs roughly $1–$2 per board foot, oak $4–$7, and walnut or cherry $8–$14+ in 2026. Enter your yard’s price in the calculator to price your exact cut list.
Should I use nominal or actual dimensions?
Actual measured dimensions. A nominal 2×4 is really 1.5″ × 3.5″ — entering nominal sizes overstates your board footage by about 30% on dimensional lumber.
Can I enter fractions like 1-1/2 inches?
Yes — enter them as decimals (1½ = 1.5). All four fields accept decimals; only quantity must be a whole number.
What is MBF, and how does it relate to board feet?
MBF means thousand board feet — the unit mills and wholesalers use for bulk orders. 1 MBF = 1,000 board feet, so a 480-board-foot stack is 0.48 MBF. If a quote says $4,500 per MBF, that is $4.50 per board foot. Retail yards rarely use MBF, but it appears on larger invoices and in timber trading.
How much extra lumber should I buy to cover waste?
Add 10–15% for clean, surfaced stock with a simple cut list. Go to 20–30% for rough-sawn boards, lower grades with knots and defects to cut around, or projects with many angled cuts. For example, a 100-board-foot cut list means ordering about 110–115 board feet of good stock — or up to 130 of rough stock.
Final Thoughts
Board feet are the language of lumber yards — and now you speak it. Enter your cut list once, compare supplier prices per board foot, and you’ll never overpay or under-order wood again.
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