WoodsMath is a free library of woodworking calculators. Every tool does one job: give you an accurate number before you cut, glue, or buy. No sign-up. No paywall. Just the math you'd otherwise do by hand at the bench.
We built WoodsMath because woodworking runs on numbers. Board feet. Cut lists. Wood movement. Shelf spans. Finish coverage. Get one wrong and you waste lumber, blow a budget, or build something that fails a season later. There are plenty of scattered tools online. Few show their work. Fewer are built for how a shop actually thinks.
Why WoodsMath exists
Most woodworking math gets done twice. Once on scrap paper, then again when the first answer looks wrong. That back-and-forth is where mistakes creep in.
WoodsMath replaces the scrap paper. You enter what you know. You get the number you need. Each calculator uses the same formula a careful woodworker would use by hand - just faster, and without the arithmetic slips.
We also believe a calculator should be honest about how it works. So every tool page explains the formula behind it. You can check the logic, not just trust a black box. That matters when the number decides how much you order or how strong a joint has to be.
Who's behind it
WoodsMath is run by Nathan Cole, a furniture maker and carpenter with over fifteen years in the shop. He's built everything from live-edge tables to full kitchen cabinet runs, and spent plenty of those years tallying board feet on the back of an envelope.
Nathan started WoodsMath after doing that math one too many times. The idea was simple: build the calculators he wished he'd had, and make sure they were right. Every tool here is checked against the formula it's meant to use, tested on real project numbers, and written up so a beginner can follow it and a pro can trust it.
The goal isn't to replace your judgment. It's to hand you a reliable starting number so you can spend your time building instead of recalculating.
How our calculators are built
Every calculator on WoodsMath follows the same standard before it goes live:
The formula comes first. We start from the accepted math for the task - board-foot volume, span tables, expansion rates, coverage rates - not a rough guess.
The inputs are checked. We test each tool with real dimensions and edge cases, so odd entries don't produce nonsense results.
The output is explained. Each page shows the formula and the assumptions behind the number, so you can see exactly how it got there.
The limits are stated. Wood is a natural material. Density, moisture, and species all shift the real-world result. Where that matters, we say so, and we tell you to confirm before you commit to an order or a structural decision.
What WoodsMath covers
The library is organized into eleven areas, so you can find the right tool by the job you're doing:
- Timber & Board - board feet, lumber cost, log volume, and stock estimates.
- Joints & Joinery - mortise, tenon, dovetail, and joint layout math.
- Finishing & Coating - coverage, coats, and mix ratios for finishes.
- Workshop & Tools - feeds, speeds, and setup numbers for shop machines.
- Furniture Design - proportions, spans, seat heights, and design ratios.
- Turning & Carving - blank sizing, speeds, and layout for lathe and carving work.
- Adhesives & Fasteners - glue coverage, screw sizing, and fastener spacing.
- Box & Case Making - box proportions, dividers, and case construction math.
- Outdoor & Decking - decking, posts, spacing, and outdoor structure estimates.
- Project Maths - general area, volume, cost, and quantity calculators.
- Reference - the constants, conversions, and charts behind the tools.
Each area grows as we add and refine tools. If a calculator you need isn't here yet, tell us - real requests shape what we build next.
Built for real work
Free, always. Every calculator is free to use, with no account and no hidden cost.
Runs on your phone. The tools are built to work at the bench, not just at a desk.
US and metric. Enter feet and inches or millimeters - the tools handle the conversion.
Clear about accuracy. Our numbers are for planning and estimating. For structural or safety-critical work, confirm with a professional before you build.
Get in touch
Found a calculator that's off, or need one that doesn't exist yet? Let us know through our contact page. WoodsMath gets better because woodworkers tell us what they actually need.