Lumber Board Feet Calculator
Calculate the total board footage for any lumber order in seconds. Enter your nominal board dimensions, length, and quantity — our calculator converts nominal sizes to actual board feet using the standard industry formula, so your material estimate is accurate before you head to the lumber yard.
How to use this calculator
- Select your nominal lumber size (e.g. 2×4, 2×6) — this is the size you ask for at the lumber yard.
- Enter the board length in feet and the number of boards in your order.
- Adjust the waste factor (5–10% for straight cuts; 12–15% for complex projects).
- Read your total board feet and cost estimate — adjust the price per BF to match your local lumber yard.
How we calculate this
Board feet (BF) are calculated from nominal dimensions — the size you ask for, not the slightly smaller actual milled size. The formula is: (nominal thickness in inches × nominal width in inches × length in feet) ÷ 12. So a single 2×4 at 8 feet = (2 × 4 × 8) ÷ 12 = 5.33 board feet. Multiply by your board count and add your chosen waste factor (5–15% is typical) to get the total you should order. The cost estimate uses a default of $0.85 per board foot — a mid-range figure for SPF #2 grade — which you can adjust.
What this calculator doesn't include
This calculator estimates board footage for a single lumber size and length. It does not account for multiple species, grades, or mixed dimensions in one order. Prices vary significantly by species (pine vs. cedar vs. Doug fir), grade, region, and supplier. Always verify pricing with your local lumber yard before ordering. Hardware (fasteners, joist hangers, etc.) is not included.
Example estimates — Lumber Board Feet
Pre-calculated for common project sizes. Includes 10% waste. Cost at ~$0.85/BF — adjust in the calculator above.
| Dimensions | Qty | BF Each | Total BF | With Waste | Est. Cost |
|---|---|---|---|---|---|
| 2×4 × 8 ft | 10 | 5.33 | 53.33 BF | 58.66 BF | $49.86 |
| 2×4 × 10 ft | 10 | 6.67 | 66.67 BF | 73.34 BF | $62.34 |
| 2×4 × 12 ft | 10 | 8 | 80 BF | 88 BF | $74.80 |
| 2×6 × 8 ft | 10 | 8 | 80 BF | 88 BF | $74.80 |
| 2×6 × 10 ft | 10 | 10 | 100 BF | 110 BF | $93.50 |
| 2×6 × 12 ft | 10 | 12 | 120 BF | 132 BF | $112.20 |
| 2×8 × 8 ft | 10 | 10.67 | 106.67 BF | 117.34 BF | $99.74 |
| 2×8 × 12 ft | 10 | 16 | 160 BF | 176 BF | $149.60 |
| 2×10 × 12 ft | 10 | 20 | 200 BF | 220 BF | $187.00 |
| 2×12 × 12 ft | 10 | 24 | 240 BF | 264 BF | $224.40 |
Frequently asked questions
A board foot is a volume measurement equal to a piece of lumber 1 foot long, 1 foot wide, and 1 inch thick — or 144 cubic inches. Lumber yards use board feet to price lumber regardless of its dimensions. A 2×4 at 8 feet contains 5.33 board feet; a 2×6 at 8 feet contains 8 board feet.
Nominal dimensions (2×4, 2×6, etc.) are the rough-cut size before kiln drying and surfacing at the mill. After milling, a 2×4 is actually 1.5" × 3.5". Board feet are calculated from nominal dimensions as an industry convention, even though the piece you receive is slightly smaller.
For straight cuts on simple projects (decks, fencing), 5–8% waste is typical. For framing with many cuts, 10–12% is standard. For complex trim work or diagonal patterns, add 15–20%. It is always cheaper to have a few extra boards than to make a second trip to the lumber yard.
SPF (Spruce-Pine-Fir) is the most common framing lumber in North America — it is affordable, widely available, and suitable for most residential framing. Douglas Fir is stronger and stiffer, making it preferred for beams, headers, and structural members where deflection matters. Prices for Doug Fir run roughly 20–40% higher than SPF.
Divide total board feet by the board feet per piece. For a 2×4 at 8 feet, each board is 5.33 BF. If you need 100 board feet total, you need 100 ÷ 5.33 = about 19 boards. Our calculator does this conversion automatically — just enter your dimensions and quantity.