Free Board Foot Calculator & Lumber Cost Estimator with Guide

In the shop, figuring out how much wood you need is key to any project. A board foot measures the amount of lumber, like a chunk that's one foot long, one foot wide, and one inch thick. This tool helps you find that amount fast, so you can buy just what you need without waste.

It's great for making tables, shelves, or boxes. Wood comes in different sizes, so this calculator adds them up right. It also shows the cost if you know the price per board foot. Think of it as counting blocks to build a fort, but for wood.

Board Foot Calculator

No. of pieces

Thickness in

Width in

Length ft in

Calculate Volume > Total 0 board feet

Price USD /board foot

Calculate Lumber Cost > Total cost 0 USD

Clear changes Reload calculator

Note: Here is another calculator which name wood measurement in cft.

The Formula This Calculator Uses

The calculator finds board feet with this main rule: Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12 × Number of Pieces

If the length is in inches instead of feet, first change it to feet by dividing by 12. For example, if thickness is 2 inches, width is 4 inches, length is 8 feet, and 1 piece: (2 × 4 × 8) ÷ 12 = 5.33 board feet.

For cost: Total Cost = Board Feet × Price per Board Foot

This comes from how lumber is sold, based on volume. It works for most wood types, but always measure rough sizes before cutting.

The Board Foot Formula (Total 3 Methods but Same Result)

((Thickness in inches - T") x (Width in inches - W") x (Length in inches - L")) ÷ 144 = Board. Feet (Bd. Ft).

Or

((Thickness in inches - T") x (Width in inches - W") x (Length in Feet- L')) ÷ 12 = Board. Feet (Bd. Ft).

Or

(Thickness in inches - T") x Sq. Ft. = Board. Feet (Bd. Ft).

It's Important to know:

• 1 board foot (Bd. Ft.) = 144 cubic inches.
• When measuring thickness, people use the rough sawn size (the size before it’s smoothed or finished), not the final smaller size you end up with.
• Board feet are used when buying wood that comes in random widths and lengths. To know how much to buy, first figure out the board footage of the parts you need for your project. That number will help you estimate the total amount of lumber required.
• Important tip: if the wood is less than 1 inch thick, it’s not counted in board feet—it’s measured in square feet instead.

👉 In short: Board foot is just a special way to measure wood volume, so you can plan and buy the right amount for your work.

Lumber Cost Estimator

   Description: Calculates total cost based on board feet and price per unit, useful for budgeting woodworking projects. 

   Formula:Total Cost = Board Feet × Price per Board Foot 

   How it works:First compute board feet, then multiply by the market price.

How to Use the Board Foot Calculator & Lumber Cost Estimator

Start with clean measurements. Use a tape to check your wood.

1. Put in the number of pieces, like 1 or more.
2. Add thickness in inches, the smallest side.
3. Add width in inches, the middle side.
4. Add length, pick feet or inches from the list.
5. Click Calculate Volume to see board feet.
6. For Lumber Cost Estimation, add price per board foot in USD.
7. Click Calculate Cost to see total Lumber cost.
8. Use Clear to start over.

Look at the picture on the right to see how to measure. Hold the tape straight. Check twice for no mistakes.

Questions Answers Related to Board Foot Calculations

Here’s the straight answer up top for each question. I’ll keep it simple, then add a quick example so it sticks.

I’ve bought lumber for years, and I still do the same thing every time: write it down, do the math slow, and don’t round early. I once rounded widths “just a little” and paid for an extra board I didn’t need. Ouch.

• How do I calculate board feet?
  • Answer:Multiply thickness (inches) × width (inches) × length (feet) ÷ 12.
  • Example:1" × 6" × 8' = 48 ÷ 12 = 4 board feet.
• How many board feet is a 2×4×8?
  • Answer:It’s 5.33 BF using nominal size, or 3.50 BF using actual size.
  • Why:Nominal 2"×4"×8' → (2×4×8)/12 = 5.33 BF. Actual 1.5"×3.5"×8' → (1.5×3.5×8)/12 = 3.5 BF. Ask which your yard uses.
• What is the formula for a board foot?
  • Answer: BF = T(in) × W(in) × L(ft) ÷ 12.
  • Tip: Hardwood thickness is sold in quarters (4/4=1", 5/4=1.25", 8/4=2"). Use that thickness in the formula.
• What are common mistakes calculating board feet?
  • Answer:Using actual thickness for hardwood (instead of its nominal), mixing units, rounding early, and forgetting length is in feet.
  • Quick list:
    • Using 13/16" for 4/4 instead of 1".
    • Entering length in inches, not feet.
    • Rounding widths before you add them up.
    • Not adding waste for knots, checks, and saw kerf.
• Is an 8‑foot board actually 8 feet?
  • Answer:Yes. Length is actual (about 96"). It’s the thickness and width that are “nominal.”
• What is “lumber per board foot”?
  • Answer:It’s a pricing unit. $/BF means cost for each 1 board foot of wood.
  • Example: If cherry is $7/BF and you buy 12 BF, price ≈ $84 before tax.
• How do I calculate how much wood I need?
  • Answer: Make a cut list, compute BF for each part, add them up, then add 10–30% waste.
  • Steps:
    • Write each part size and quantity.
    • BF each piece with the formula.
    • Total the BF.
    • Add waste (10% for clear stock and simple parts; up to 30% for lots of defects, grain match, or curved cuts).
• Is a board foot always 144 cubic inches?
  • Answer: Yes. By definition, 1 BF = 144 cubic inches = 1" × 12" × 12" = 1/12 cubic foot.
• How many square feet is 200 board feet?
  • Answer:Square feet = Board feet ÷ thickness (inches).
  • Examples:
    • At 1" thick: 200 BF ÷ 1 = 200 sq ft.
    • At 3/4" thick: 200 ÷ 0.75 = 266.67 sq ft.
    • At 2" thick: 200 ÷ 2 = 100 sq ft.
• How many board feet are in a 12" log?
  • Answer: You can’t give one number without length and a log rule. If you use the Doyle rule: BF = ((D − 4)² × L) ÷ 16, where D is small‑end diameter inside bark (inches) and L is length (feet).
  • Examples with Doyle:
    • 12" × 8' log: ((12−4)² × 8)/16 = (8² × 8)/16 = 32 BF.
    • 12" × 16' log: ((12−4)² × 16)/16 = 64 BF.
  • Note: Scribner and International 1/4 give different totals.
• What is the shortcut for board feet?
  • Answer:For 1" thick stock, use width(in) × length(ft) ÷ 12. Then scale for thicker pieces.
  • Handy multipliers:
    • 4/4 (1"): ×1
    • 5/4 (1.25"): ×1.25
    • 6/4 (1.5"): ×1.5
    • 8/4 (2"): ×2
• How many square feet is 650 board feet?
  • Answer:Square feet = BF ÷ thickness (inches).
  • Examples:
    • 1": 650 sq ft.
    • 3/4": 650 ÷ 0.75 = 866.67 sq ft.
    • 2": 650 ÷ 2 = 325 sq ft.
• How many square feet does a 55‑gallon drum of spray foam do?
  • Answer: Spray foam is rated in board feet. 1 BF covers 1 sq ft at 1" thick. A “55‑gallon drum” is one part of a two‑part set; coverage depends on the manufacturer’s stated yield (board feet per set) and the thickness you spray.
  • How to figure it: Square feet = (manufacturer BF yield) ÷ (thickness in inches).
  • Example:If a set is rated at Y BF and you spray 2", coverage ≈ Y ÷ 2 sq ft. Check the product data sheet for Y.
• How much does a board foot typically cost?
  • Answer: There isn’t one price. It depends on species, grade, thickness, and region.
  • Practical tip:Call your local yard or check their price list. Many common U.S. hardwoods run anywhere from a few dollars to well over $20 per BF. Exotics can be higher.

Everyday picture
Think of a board foot like a one‑inch‑thick pizza that’s 12" by 12". If your slice is thicker, you get less surface area from the same “pizza.” That’s why you divide by thickness to get square feet.

📏 Common Board Feet Calculations

👉 Quick hack:if you forget the formula, just think:
Thickness × Width × Length ÷ 12

For most common boards, the board feet number is almost the same as the width (like a 2x6x8 is ~5.5 BF). Makes it easy to guess in your head.

Quick personal tip
I keep a tiny card in my wallet: “BF = T×W×L ÷ 12” and the 4/4, 5/4, 8/4 multipliers. It has saved me at the yard more than once.

Here’s your Board Feet Cheat-Sheet as a visual chart 📊. Super handy to glance at while buying lumber - no need to keep crunching the formula every time.