RatioStep: Ratio Calculator

Enter three values. Find the fourth. See how the calculation works.

RatioStep is a focused calculator for direct and inverse proportions. Use it to scale a recipe, compare quantities, or check a proportion exercise.

• Solve for any of the four values.
• Switch between direct and inverse proportion.
• Open the explanation to see the arithmetic steps.
• Choose a row or stacked layout.
• Set the display precision from one to six decimal places.
• Copy the answer or paste a value.
• Use English, Spanish, or Portuguese (Portugal).

Calculations run on your iPhone. No account, ads, tracking, or internet connection is needed to calculate. Your preferences stay on your device.

Requires iOS 18 or later.