Rule of three calculator
Solve direct and inverse rule of three with the formula shown.
Our rule of three calculator computes instantly as you type and shows every intermediate result so you understand the math. Free, no sign-up, works on any device.
Formula: Direct rule of three: if A → B then C → X = (B × C) / A. Inverse: X = (A × B) / C.
Rule of three calculator: how to use it
- Enter your values (you can switch units).
- The result is calculated automatically.
- Review the breakdown and results table.
- Copy the result in one click.
Features
- Real-time calculation.
- Detailed breakdown and tables.
- Metric and imperial units.
- Private: nothing leaves your browser.
Frequently asked questions
Are the results accurate?
We use standard formulas with double-precision math. For important financial or medical decisions, consult a professional.
Do you store my data?
No. Calculations run in your browser.
Can I use it on my phone?
Yes, it is mobile-optimized.