A board foot calculator helps you determine the exact volume and cost of lumber before you buy. Whether you are pricing hardwood for a woodworking project or estimating studs for a framing job, calculating board footage and stud counts upfront prevents over-ordering and keeps your budget on track.
Board Foot Calculator
Framing / Stud Calculator
Nominal vs Actual Lumber Dimensions
| Nominal Size | Actual Size (in) | Common Use |
|---|---|---|
| 1×4 | 3/4" × 3-1/2" | Trim, furring strips |
| 1×6 | 3/4" × 5-1/2" | Shelving, fence boards |
| 1×8 | 3/4" × 7-1/4" | Shelving, sheathing |
| 1×12 | 3/4" × 11-1/4" | Wide shelving, fascia |
| 2×4 | 1-1/2" × 3-1/2" | Wall framing, studs |
| 2×6 | 1-1/2" × 5-1/2" | Exterior walls, floor joists |
| 2×8 | 1-1/2" × 7-1/4" | Floor joists, headers |
| 2×10 | 1-1/2" × 9-1/4" | Floor joists, headers |
| 2×12 | 1-1/2" × 11-1/4" | Large headers, ridge boards |
| 4×4 | 3-1/2" × 3-1/2" | Posts, deck supports |
How to Use the Lumber & Board Foot Calculator
Buying lumber without calculating board footage first leads to wasted money and extra trips to the store. Our free board foot calculator gives you accurate volume and cost estimates in seconds, and the framing mode counts every stud, plate, and header you need for a wall.
Step 1: Choose Your Mode
Switch between Board Foot Calculator and Framing / Stud Calculator using the tabs at the top. Board foot mode is ideal for pricing hardwood, softwood, or any lumber sold by the board foot. Framing mode is designed specifically for wall framing projects where you need stud counts and plate lengths.
Step 2: Board Foot Mode
Use the quick-select buttons to populate common nominal sizes (1×4, 2×4, 2×6, etc.), or enter custom thickness and width values. Set the board length in feet and the quantity you plan to buy. The calculator uses the standard formula: board feet = (thickness × width × length) / 12. Optionally, enter a price per board foot to see the total cost.
Step 3: Build a Lumber List
Click Add to List to save an item and start building a running total. This is useful when you need several different sizes for the same project. Each item shows its board footage and cost, with a grand total at the bottom. Remove individual items with the delete button, or clear everything and start over.
Step 4: Framing / Stud Mode
Enter the wall length and height, then select your stud spacing (16 inches on center for load-bearing walls, or 24 inches for non-bearing partitions). Choose between 2×4 and 2×6 studs. Add the number of doors and windows to account for king and jack studs at each opening.
Step 5: Review the Framing Breakdown
The calculator shows the total stud count, linear feet of plates needed (one bottom plate plus a double top plate), and the number of headers. The breakdown table details each component: regular studs, king studs, jack studs, bottom plate, and top plates. Enter a price per stud for an instant cost estimate.
Understanding Board Feet
One board foot equals a piece of lumber one inch thick, twelve inches wide, and one foot long, or 144 cubic inches. Lumber yards use board feet to price rough-sawn hardwoods and specialty wood. For dimensional lumber like 2×4 studs, pricing is usually per piece, which is why the framing mode uses a per-stud price instead.
FAQ
Is this lumber calculator free to use?
Yes, the board foot calculator and framing estimator are completely free with no limits. Calculate as many lumber projects as you need. No signup or account required, and all calculations run locally in your browser.
Is my project data private?
Yes, everything runs entirely in your browser. Your dimensions, quantities, and cost estimates are never sent to a server or stored remotely. No data ever leaves your device.
How do you calculate board feet?
Board feet are calculated using the formula: (thickness in inches x width in inches x length in feet) / 12. One board foot equals a piece of lumber 1 inch thick, 12 inches wide, and 1 foot long, or 144 cubic inches of wood.
What is the difference between nominal and actual lumber dimensions?
Nominal dimensions are the name used to sell lumber (like 2x4), while actual dimensions are the real measurements after milling and drying. A nominal 2x4 actually measures 1.5 inches by 3.5 inches. The reference table in the calculator shows all common conversions.
How many studs do I need for a wall?
The basic formula is: number of studs = (wall length in inches / stud spacing) + 1. Standard spacing is 16 inches on center for load-bearing walls or 24 inches for non-bearing walls. Add extra studs for each door (2 king studs + 2 jack studs) and each window (2 king + 2 jack studs).
What stud spacing should I use: 16 or 24 inches?
Use 16 inches on center for exterior walls, load-bearing walls, and any wall that supports a floor or roof above. Use 24 inches on center for interior non-load-bearing partition walls. When in doubt, check your local building code or use 16 inches for safety.
How do I calculate lumber for top and bottom plates?
Bottom plate requires one length of the wall. Top plate typically requires a double plate (two lengths), so total plate lumber is 3 times the wall length. Use the same size lumber as your studs, usually 2x4 or 2x6.
What size header do I need over a door or window?
Header size depends on the span and load above. For non-bearing walls, a flat 2x4 is usually sufficient. For bearing walls: spans up to 4 feet use doubled 2x6, up to 6 feet use doubled 2x8, up to 8 feet use doubled 2x10, and up to 10 feet use doubled 2x12. Always verify with local building codes.