Free tool
A calculator that actually understands units
Type math the way you think it — with the units attached. Calcanvas runs full dimensional analysis on every expression, so conversions happen automatically and unit mistakes get caught before they cost you.
Live demo — runs in your browser. Try editing the expression.
How unit-aware calculation works
Every quantity carries its dimensions through the whole calculation, the same way you were taught to do it on paper. Compatible units convert automatically:
- 5 km + 300 m = 5.3 km
- 12 N / (4 mm²) = 3 N/mm²
- 120 W × 3 h = 360 W·h
And incompatible units fail loudly instead of producing a plausible-looking wrong answer:
- 5 km + 2 kg →Cannot convert from ‘km’ ([length]) to ‘kg’ ([mass])
That single behavior — dimensions checked on every operation — is what spreadsheets and ordinary calculators can't give you, and it is why unit-aware worksheets are the tool of choice for engineering calculations. It is also the core of why people pick Calcanvas as a Mathcad alternative.
From one-line answers to full worksheets
The calculator above evaluates one expression at a time. In a full Calcanvas worksheet, cells share variables — define P = 2500 N in one cell, then use P anywhere on the canvas, and everything recomputes when it changes. Your math sits on an infinite collaborative whiteboard next to sketches and images, entirely in the browser.
FAQ
Frequently asked questions
Which units does the calculator support?
The demo on this page handles common SI units — lengths (mm to km), mass, time, force (N, kN, MN), pressure (Pa to GPa), energy, power, volume, and percentages. The full Calcanvas editor computes server-side on Pint's comprehensive unit registry, which covers far more, including imperial units.
What happens when units don't match?
You get a clear dimensional-analysis error instead of a wrong number. For example, 5 km + 2 kg returns: Cannot convert from 'km' ([length]) to 'kg' ([mass]).
Is this calculator free?
Yes. The calculator on this page is free with no sign-up. The full Calcanvas worksheet — multiple cells with shared variables on an infinite canvas — is also free while in early access.
Can I save my calculations?
Yes. Create a free account and your calculations live in projects on an infinite canvas, where formulas can share variables (define P = 2500 N in one cell and use P in the next), alongside sketches and images.