RatioStep

iPhone · iOS 18 or later

Three values.
The fourth, explained.

RatioStep solves direct and inverse proportions. Enter three values, see the answer, and open the steps when you want to understand the calculation.

Try your first calculation

  1. Enter 3 in the first cell.
  2. Tap the arrow to move to the next cell.
  3. Enter 6.
  4. Tap the arrow again.
  5. Enter 5. The answer is 10.

Tap How it works to see the explanation. Scroll the calculation area if the steps extend below the keypad.

Common questions

How do I switch to an inverse proportion?

Open Settings and choose Inverse under Proportion. Use Direct when both quantities grow together. Use Inverse when one grows as the other shrinks.

Can I solve for a different cell?

Touch and hold the cell you want to find, then choose Solve for this. Fill the other three cells.

What does the ellipsis after a result mean?

The result has more decimal places than the current display limit. Open Settings to choose between one and six decimal places. The displayed decimal is truncated, not rounded up.

How do I copy, paste, or start again?

Tap the answer to copy it. Touch and hold an input cell to paste a number or clear that cell. Tap Clear all to remove the current inputs.

Does the calculator need an internet connection?

No. Calculations and saved preferences work on your device. Opening these support and privacy pages uses your browser and an internet connection.

Need help?

Contact Gianfranco Gasbarri at [email protected]. Include your iOS version, the app version, and the steps that caused the problem. Please leave out private information.

Email support

The app supports English, Spanish, and European Portuguese.