Lumber Calculator
Calculate board feet, lumber quantities, and total costs for your construction or woodworking projects
Calculating lumber quantities and costs is essential for budgeting construction and woodworking projects. Our lumber calculator helps you:
- Determine the total board feet of lumber needed
- Calculate the cost based on current lumber prices
- Convert between different measurement units
- Plan material purchases efficiently
To use the calculator, enter the dimensions (length, width, and thickness) of your lumber, the quantity needed, and the price per board foot. The calculator will instantly provide the total board feet and estimated cost.
The standard formula for calculating board feet is:
Board Feet = (Length in inches × Width in inches × Thickness in inches) ÷ 144
For example, a piece of lumber that is 96 inches long, 6 inches wide, and 1 inch thick would be:
(96 × 6 × 1) ÷ 144 = 4 board feet
If you're working with feet instead of inches for the length, you can use this simplified formula:
Board Feet = (Length in feet × Width in inches × Thickness in inches) ÷ 12
Lumber is typically sold in standard sizes. Here are some common dimensional lumber sizes (nominal vs. actual):
| Nominal Size | Actual Size (inches) | Common Uses |
|---|---|---|
| 1×2 | 3/4 × 1-1/2 | Trim, furring strips |
| 1×4 | 3/4 × 3-1/2 | Trim, shelving, fascia |
| 1×6 | 3/4 × 5-1/2 | Siding, shelving, trim |
| 1×8 | 3/4 × 7-1/4 | Siding, shelving |
| 2×4 | 1-1/2 × 3-1/2 | Wall framing, general construction |
| 2×6 | 1-1/2 × 5-1/2 | Wall/roof framing, decking |
| 2×8 | 1-1/2 × 7-1/4 | Floor joists, headers |
| 2×10 | 1-1/2 × 9-1/4 | Floor joists, headers, beams |
| 2×12 | 1-1/2 × 11-1/4 | Floor joists, headers, beams |
| 4×4 | 3-1/2 × 3-1/2 | Posts, fence posts, heavy construction |
Standard lumber lengths typically range from 8 to 16 feet in 2-foot increments, though some specialty suppliers may offer different lengths.
Lumber is graded based on appearance and structural characteristics. Understanding these grades can help you choose the right lumber for your project:
Softwood Grades:
- Select/Clear: Highest quality with few to no defects, ideal for fine woodworking and visible applications
- Finish: High-quality lumber with minor defects, suitable for interior trim and cabinetry
- Common: Available in #1, #2, and #3 grades (with #1 being the highest quality), suitable for general construction
- Construction/Standard/Utility: Lower grades used for general framing and construction where appearance is less important
Hardwood Grades:
- FAS (First and Second): Premium grade with minimal defects, used for high-end furniture and cabinetry
- Select: High quality with slightly more defects than FAS, good for visible applications
- No. 1 Common: Medium quality with some defects, suitable for cabinets, furniture, and millwork
- No. 2 Common: More defects but still usable for many projects, economical choice for less visible applications
Several factors influence the cost of lumber:
- Wood species: Exotic and hardwood species typically cost more than common softwoods
- Grade and quality: Higher grades with fewer defects command premium prices
- Dimensions: Larger and longer pieces generally cost more per board foot
- Treatment: Pressure-treated, kiln-dried, or specially treated lumber costs more than untreated wood
- Market conditions: Supply chain issues, seasonal demand, and economic factors can cause significant price fluctuations
- Location: Regional availability and transportation costs affect pricing
- Quantity: Bulk purchases may qualify for discounts
When budgeting for a project, it's advisable to check current lumber prices as they can vary significantly over time.
- Inspect before buying: Check for warping, cupping, twisting, knots, and splits
- Buy extra: Purchase 10-15% more lumber than calculated to account for waste and defects
- Consider moisture content: For interior projects, use kiln-dried lumber with lower moisture content to prevent warping
- Shop around: Prices can vary significantly between big box stores, lumberyards, and specialty suppliers
- Buy in bulk: If you have storage space, buying larger quantities can save money
- Consider alternatives: Engineered wood products like plywood, OSB, or MDF might be more cost-effective for some applications
- Time your purchase: Lumber prices often fluctuate seasonally, with winter sometimes offering better deals
- Check for straightness: Look down the length of boards to check for straightness before purchasing
What is a board foot?
A board foot is a unit of volume for measuring lumber in the United States and Canada. One board foot equals 144 cubic inches, which is equivalent to a piece of wood measuring 1 foot × 1 foot × 1 inch (12" × 12" × 1").
How do I calculate the cost of lumber?
To calculate the cost of lumber, first determine the total board feet by multiplying length × width × thickness (all in inches) and dividing by 144. Then multiply the total board feet by the price per board foot to get the total cost.
Why are nominal lumber dimensions different from actual dimensions?
Nominal dimensions refer to the size of lumber before it's dried and planed (smoothed). During processing, lumber shrinks and loses approximately 1/4" to 3/4" in each dimension. For example, a nominal 2×4 actually measures about 1.5" × 3.5".
What's the difference between hardwood and softwood lumber?
Hardwood comes from deciduous trees (like oak, maple, and walnut) and is generally denser and more durable. Softwood comes from coniferous trees (like pine, cedar, and fir) and is typically less dense, easier to work with, and less expensive. Despite the names, some hardwoods are actually softer than some softwoods.
How much extra lumber should I buy for a project?
It's generally recommended to add 10-15% extra to your lumber calculations to account for waste, mistakes, and defects. For complex projects with many cuts or if you're a beginner, you might want to add up to 20%.