24 practical calculators for carpenters, woodworkers, and people who would rather build something than spend half the day doing math.

There’s a special kind of frustration in cutting a perfectly good piece of lumber, only to discover it’s 12 mm too short. Now you have two problems: the missing 12 mm and a new piece of expensive firewood.

That’s the sort of thing Carpentry & Trim Calculator is here to help with.

It’s an iPhone and iPad app with 24 tools for woodworking, framing, roofing, trim installation, and material calculations. Nothing magical. Just useful numbers, layouts, and measurements when you need them.

Who Is This App For?

Carpenters, cabinetmakers, framers, finish carpenters, contractors, and DIY enthusiasts.

Basically, anyone who works with wood and occasionally looks at a measurement thinking, “This can’t be right.”

Experienced professionals already know their formulas. But remembering everything, checking dimensions, and doing the same calculations repeatedly gets old pretty fast.

And if you’re building your first deck, installing crown molding, or trying to figure out stair spacing, a little help with the numbers doesn’t hurt either.

What Can You Actually Calculate?

Quite a few things. We started with the common carpentry calculations and kept adding tools for those little problems that show up during a project.

Framing, decks, and roofs

Plan wall framing with doors and windows, calculate rafters, work with hip, gable, and skillion roofs, design decks, or figure out fence spacing. The calculators help turn dimensions into layouts and usable measurements.

Trim, stairs, and finish carpentry

Crown molding, board and batten, wainscoting, stair layouts, baluster spacing, cabinet doors, and general trim calculations. The kind of work where a tiny measurement error can become very visible when everything is installed.

Lumber and material estimates

Calculate board feet, plywood quantities, lumber weight, and other material requirements. There’s also a wood movement calculator, because apparently wood doesn’t consider your carefully measured dimensions a permanent agreement.

The app supports both metric and imperial units. Several calculators include visual diagrams, and the advanced planning tools can generate PDF reports with measurements and layouts.

Why We Built It This Way

As a developer, I like tools that do one thing well. Or, in this case, 24 related things without turning the interface into a spaceship dashboard.

The idea behind Carpentry & Trim Calculator was pretty simple: enter your measurements, get useful results, and get back to the actual project.

No need to remember which spreadsheet had that roof formula. No need to search through five browser tabs just to calculate material quantities.

And when you change a dimension, you can recalculate instead of starting the whole thing again.

It’s not meant to replace carpentry experience. An app can’t tell you whether that old wall is straight, whether the wood is any good, or why nothing in a 40-year-old house seems to be square.

But it can make the math part less annoying.

A Few Things Worth Knowing

You can download the app for free, with additional functionality available through in-app purchases.

It runs on iPhone and iPad, supports multiple languages, and includes tools for small workshop projects as well as larger construction layouts.

We’re continuing to improve it, fix issues, and add useful calculations. Some ideas come from obvious everyday problems. Others come from feedback and questions about things we hadn’t considered before.

That’s how a useful toolbox grows, really.

Less Guessing. More Building.

If you’re planning a deck, working out a stair layout, measuring crown molding, or just trying to avoid buying twice as much plywood as you need, give the app a try.

It won’t make you a better carpenter overnight. But it might save you a few calculations, a bit of time, and possibly one very unfortunate piece of lumber.