Board Foot Calculator

Calculate the volume of lumber in board feet

Enter the number of pieces, thickness, width, and length to find the total board feet

CreatorFrank Zhao

Number of Pieces

Thickness

Width

Length

Cost Calculator

Price per Board Foot

USD

/ board foot

Whether you're a seasoned woodworker, a DIY enthusiast tackling your first project, or a contractor pricing out a job, understanding board feet is essential. This calculator takes the guesswork out of lumber estimation—just plug in your dimensions, and you'll know exactly how much wood you need and what it'll cost.

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What Is a Board Foot, Anyway?

Think of a board foot as the lumber industry's way of measuring volume. While square feet tells you about surface area (great for flooring), board feet tells you about the actual amount of wood you're getting—which matters when you're paying for it!

🪵 One board foot = a piece of wood that's 12 inches long × 12 inches wide × 1 inch thick

Here's another way to think about it: imagine a standard ruler (12 inches). Now picture a square piece of wood that's one ruler-length on each side and one inch thick. That's exactly one board foot.

Unit conversions if you need them:

1 board foot = 144 cubic inches
1 board foot = 1/12 cubic foot
1 board foot ≈ 2,360 cubic centimeters

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The Board Foot Formula (It's Simpler Than You Think!)

The math behind board feet is refreshingly straightforward. Here's the classic formula:

Board Feet = (Thickness × Width × Length) ÷ 144

(when all measurements are in inches)

Or, if you prefer working with feet for length (which is often more practical):

Board Feet = (Thickness (in) × Width (in) × Length (ft)) ÷ 12

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Pro Tip: Our calculator handles all the unit conversions automatically. Just enter your measurements in whatever units you have—feet, inches, meters, centimeters—and we'll do the math for you.

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Let's Walk Through a Real Example

Say you're building a dining table and need to buy some walnut boards. Here's exactly how to figure out what you need:

Count your pieces

You need 5 boards for the tabletop.

Measure each board

Each board is 8 feet long, 10 inches wide, and 1.25 inches thick.

Calculate board feet per piece

(1.25 × 10 × 8) ÷ 12 = 8.33 board feet

Multiply by quantity

8.33 × 5 pieces = 41.67 total board feet

Calculate the cost

If walnut costs $8.50 per board foot:

41.67 × $8.50 = $354.20

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When Do You Actually Need Board Feet?

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Furniture Building

Calculating how much hardwood you need for tables, chairs, cabinets, or shelving projects.

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Construction Estimates

Framing lumber for walls, floors, and roofs—especially for custom or renovation work.

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Sawmill Purchases

Buying rough-sawn lumber directly from mills where pricing is always in board feet.

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Lumber Yard Shopping

Comparing prices across different board sizes to find the best value for your project.

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Timber Sales

Estimating the value of standing timber or logs for forestry and logging operations.

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Project Bidding

Contractors need accurate material estimates to provide fair quotes to clients.

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Quick Reference: 2×4 Board Feet by Length

Here's a handy chart for one of the most common lumber sizes (nominal 2×4, which is actually 1.5" × 3.5"):

Length (ft)	Board Feet
6	4
8	5⅓
10	6⅔
12	8
14	9⅓
16	10⅔
18	12
20	13⅓
24	16
26	17⅓

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Pro Tips From the Workshop

Always add 10-20% for waste

Between cutting mistakes, defects in the wood, and sawdust, you'll always lose some material. Better to have a little extra than to make another trip to the lumber yard.

Nominal vs. actual dimensions

A "2×4" is actually 1.5" × 3.5" after milling. For rough-sawn lumber, you'll get the full dimension, but S4S (surfaced on all sides) lumber is smaller.

Compare price per board foot

Different board sizes can have wildly different per-board prices. Calculate the board feet to compare apples to apples and find the real bargain.

Hardwoods vs. softwoods pricing

Softwoods like pine are often sold by linear foot, while hardwoods (oak, walnut, maple) are almost always priced by board foot. Know what you're looking at!

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Frequently Asked Questions

What's the difference between board feet and linear feet?

Great question! They measure completely different things:

Linear feet measures just the length—like measuring a rope. A 10-foot board is 10 linear feet, regardless of how thick or wide it is.
Board feet measures volume—it accounts for thickness, width, AND length. A thick, wide 10-foot board has more board feet than a thin, narrow one.

Think of it this way: if you're buying rope, linear feet makes sense. If you're buying a block of wood, you need board feet!

How do I calculate board feet in a log?

Logs are tricky because they're round, not rectangular. Lumbermen use special log rules, with the most common being:

Doyle Rule — Conservative estimate, good for small logs
Scribner Rule — Middle ground, widely used
International ¼" Rule — Most accurate, especially for larger logs

A rough estimate you can do yourself:

Board Feet ≈ ((Diameter - 4) ÷ 4)² × Length

Where diameter is the small end in inches (without bark) and length is in feet.

How much does a board foot of oak weigh?

It depends on the type of oak and how dry it is, but here are some ballpark figures:

Red Oak: About 3.5-4 lbs per board foot
White Oak: About 4-4.5 lbs per board foot
Live Oak: Can be 5+ lbs per board foot (it's incredibly dense!)

Green (freshly cut) wood will weigh significantly more due to water content. Kiln-dried lumber is lighter and more consistent.

Can I convert square feet to board feet?

Not directly—they measure different things! But if you know the thickness, you can make the conversion:

Board Feet = Square Feet × Thickness (in inches)

So 100 square feet of 1-inch thick lumber = 100 board feet. But 100 square feet of 2-inch thick lumber = 200 board feet.

What is board foot insulation?

When it comes to spray foam insulation, contractors use board feet to measure volume coverage. One board foot of insulation covers 1 square foot at 1 inch of thickness.

So if you need to insulate a 500 sq ft wall with 3 inches of foam:

500 × 3 = 1,500 board feet of insulation needed

Foam contractors typically price their work per board foot installed.

Why do lumber dimensions say 2×4 when it's really 1.5×3.5?

The "2×4" is the nominal dimension—what the board was before it was dried and planed smooth. Here's what actually happens:

The log is cut to roughly 2" × 4"
The wood is dried (and shrinks slightly)
All four sides are planed smooth (removing about 1/4" from each side)

The result? A board that's actually 1.5" × 3.5". This has been industry standard since the 1960s. When calculating board feet for dimensional lumber, use the actual dimensions for accuracy!