Ratio Calculator
Simplify ratios or solve for missing values in proportions (A:B = C:D). Perfect for resizing images, cooking conversions, and algebra.
Solve A : B = C : D
Leave one field empty to calculate it.
How Ratio Calculations Work
A ratio compares two quantities. There are two common operations you might need: simplification and solving proportions.
1. Simplification
Simplifying a ratio involves reducing the numbers to their smallest whole number form while maintaining the same proportion. We find the Greatest Common Divisor (GCD) of both numbers and divide them by it.
12 : 16 → divide by 4 → 3 : 4
2. Solving Proportions (Rule of Three)
A proportion states that two ratios are equal: A : B = C : D. If you know three of these values, you can solve for the fourth using cross-multiplication.
- Solve for A: $A = (B \times C) / D$
- Solve for B: $B = (A \times D) / C$
- Solve for C: $C = (A \times D) / B$
- Solve for D: $D = (B \times C) / A$
This is commonly used for resizing images (aspect ratio), converting recipes, or calculating map distances.
? Frequently Asked Questions
The Golden Ratio is a special number approximately equal to 1.618. It appears frequently in geometry, art, and nature.
Yes, ratios can involve decimals (e.g., 1.5 : 2). However, simplified ratios are typically expressed as whole numbers (3 : 4).
Enter your original width and height as A and B. Then enter your new desired width as C (leaving D empty), or new height as D (leaving C empty). The calculator will find the missing dimension to maintain the aspect ratio.