Lumber Calculator
This calculator estimates the total linear feet and cost for a dimensional-lumber project — studs, deck boards, framing, trim — from the length of each board, how many you need, and the price. Enter your numbers and the totals update as you type.
What this calculator is for
Dimensional lumber — 2×4s, deck boards, framing studs — is sold by the piece or by the linear foot, where only length matters for the count. That makes it different from rough hardwood, which is priced by volume (the board foot). This tool handles the linear-foot case: tell it how long each board is and how many you need, and it returns total footage and total cost.
If you’re buying rough hardwood quoted “per board foot” instead, use our board foot calculator — it folds thickness and width into the price. This page is for the run-of-the-mill “how many boards, how much will it cost” question.
A note on nominal vs. actual size
Dimensional lumber is labeled by its nominal size, not its real one. A “2×4” is milled and dried down to about 1½″ × 3½″; a “1×6” is roughly ¾″ × 5½″. Length, though, is honest — an 8-foot 2×4 really is 8 feet — which is why a linear-foot calculation stays accurate even though the cross-section is undersized. Only worry about the nominal-vs-actual gap when you’re fitting boards together, not when you’re counting footage.
The formula (so you can check the math)
Total linear feet = Length per board × Number of boards
Total cost (by the foot) = Total linear feet × Price per linear foot
Total cost (by the board) = Price per board × Number of boards
Worked example
Say you need 10 boards, each 8 feet long, at $0.90 per linear foot:
Total linear feet = 8 × 10 = 80 lin ft
Total cost = 80 × $0.90 = $72.00
If the yard prices the same board at $7.20 each instead, 10 boards come to $72.00 — the calculator accepts whichever number you have on the price tag.
Who this is for
This is built for DIYers and homeowners planning a deck, a stud wall, fencing, or trim — anywhere lumber is bought by the stick. Measure your runs, divide by the length of the boards your yard stocks to get a piece count, then plug that in for a fast budget. For hardwood furniture stock sold by volume, reach for the board foot calculator or wood CFT calculator instead.
Once your lumber is home, flatten and square it with the best cordless planers, then bring it to a finish with the right wood sander.
Frequently Asked Questions
What’s the difference between a linear foot and a board foot?
A linear (running) foot measures only length — perfect for dimensional lumber like 2×4s sold by the stick. A board foot measures volume (a 1″ × 12″ × 12″ block) and is how rough hardwood is priced. Use this calculator for linear feet; use the board foot calculator for volume-priced hardwood.
How many 2×4s do I need?
Divide the total length you need to cover by the length of the 2×4s your store sells (usually 8, 10, or 12 feet), then round up for waste. For stud walls, a common rule is one stud per 16 inches of wall run, plus extras for plates, corners, and openings. Enter the resulting piece count above to price it.
Should I add extra for waste?
Yes. Add about 10% for straight dimensional runs and 15–20% for anything with lots of cuts, miters, or defect-prone material. The calculator gives the exact footage for what you enter, so build the buffer into your quantity.
Does this account for board thickness and width?
No — for linear-foot pricing, only length and quantity affect the count and cost, so thickness and width don’t enter the math. If your lumber is priced by the board foot (where thickness and width do matter), use the board foot calculator instead.