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Ratio Calculator : Solve Proportions & Simplify Ratios

Solve ratio proportions effortlessly. Fill in any three values in the proportion A:B = C:D to solve for the fourth, or simplify ratios like 45:60 to 3:4.

Interactive Calculator

100% Client-Side Engine

Enter 3 values and leave one box empty to solve for the missing variable.

=
Solved Variable (D)
D = 1080

Cross-Multiplication Steps

  • Rearranging for D: D = (B × C) ÷ A
  • Calculation: (9 × 1920) ÷ 16 = 1080

Step-by-Step Examples

Scaling an Image Proportion (16:9)

Finding height for width 1920 with ratio 16:9.

Inputs: A: 16, B: 9, C: 1920, D: ?
Result: D = 1080

D = (9 * 1920) / 16 = 1080 (1920x1080 Full HD).

How to Use This Tool

  1. To solve a proportion: enter 3 values and leave one blank.
  2. To simplify: enter values A and B.
  3. Click Calculate to see the solved value and step-by-step cross-multiplication.

Frequently Asked Questions

Cross-multiply the opposite terms: if A/B = C/D, then A × D = B × C. Divide by the known coefficient to isolate the missing variable.