Calculate anything with
The solvers do the work for you
Pick a formula, enter the variables you know, leave one blank, click Calculate, and the solver finds your solution in any units, with the algebra and unit conversions shown. Every solver pairs its calculator with a learning zone: what the formula means, where it came from, and how it's used in the field.
Find a solver →In the Exam Room, it's all on you
Quick three-to-five minute interactive lessons, Grade 10 through university, where you choose the formula yourself, rearrange it yourself, and place the values and their units yourself. Nothing is solved for you. Practise, track your improvement over time, and compete with your classmates and friends.
Open the Exam Room →- 1,930formula solvers
- 800lessons
- 342constants, sourced
- 4,820answers checked by hand
- 0accounts needed
The story
- 2011
An idea in a chemical engineering program
I had learned that the fastest way into any course was through its formulas. The trouble was the long, multi-step problems: mixed units, surface areas, little carried values, physical constants. They kept ending the same way: a table of classmates, several different answers, and no way to tell whose was right. I wanted a site that would settle the question. Enter what you know, leave one variable blank, and see the answer with the work shown, so the debate could end and the learning could carry on.
- 2011 to 2025
Fifteen years of apprenticeship
Building it took longer than imagining it. I taught myself HTML, CSS, and PHP from scratch, through online courses, eBooks, formal examples, and a great deal of trial and error. A first version took shape in 2011, and several more followed. Along the way I picked up frameworks, shipped an Android app, then an iOS app. Every detour was another apprenticeship for this one. The project went cold more than once, set aside for children, for work, for a life's worth of commitments. It never stopped being a passion.
- 2026
The coding as fast as the thinking
Building with Claude finally made the coding as fast as the thinking, and a working version came together in under a day, larger than anything I had sketched across fifteen years of imagining it.
- Today
For students, trades, and anyone curious
And here it is, at last: for students, for trades, for anyone curious enough to want the work shown, and for my own kids, who will grow with it. It will keep growing from here.
Who builds this
Hi, I'm Mathieu! I run HYDRONIC Water Treatment in North Vancouver, and is the passion project I've been dreaming about since my chemical engineering degree in 2011. I've spent over 15 years in industry, ten of them in water treatment: HVAC water systems first, then a few years designing chemical applications and mine water treatment plants, and today I advise on more than 250 building water systems.
I decide what goes on the site and how it works, and I'd love to hear what you'd like to see next.
Mathieu on LinkedIn →How it's built and checked
- ✓Every solver has to reproduce answers worked out by hand, all 4,820 of them, before anything goes live.
- ✓Every constant tells you where it came from, and whether it's exact, measured or a typical value.
- ✓I build the site with help from Claude, an AI model, which drafts most of the formulas, writing and code. What keeps the numbers honest is testing.
Spot a number that looks off? Please tell me. I'll fix it and add a test so it stays fixed.