Ratio Calculator: How to Simplify, Scale, and Use Ratios

Ratios show the relationship between quantities. Whether you’re scaling a recipe, mixing concrete, or splitting expenses — ratios are everywhere.

What is a ratio?

A ratio compares two or more quantities. The ratio 3:2 means “for every 3 of the first, there are 2 of the second.” It can also be written as 3/2 or “3 to 2.”

Simplifying ratios

Divide both parts by their GCD (Greatest Common Divisor).

Example: Simplify 24:36

• GCD of 24 and 36 = 12
• 24÷12 : 36÷12 = 2:3

Scaling ratios (recipe scaling)

To scale a ratio, multiply all parts by the same factor.

Example: A recipe calls for flour:sugar = 3:1 and uses 300g flour. You want to double it:

• 3:1 × 2 = 6:2
• Flour: 600g, Sugar: 200g

Finding equivalent ratios

If A:B = 3:4 and A = 15, what is B?

• Scale factor = 15 ÷ 3 = 5
• B = 4 × 5 = 20

Ratio to percentage

Convert A:B to percentages:

• Total parts = A + B
• A% = (A ÷ Total) × 100
• B% = (B ÷ Total) × 100

Example: 3:2 → Total = 5 → A = 60%, B = 40%

Real-world uses

• Cooking: Scaling recipes up or down
• Finance: Debt-to-income ratio, price-to-earnings ratio
• Construction: Cement:sand:gravel mixing ratios
• Photography: Aspect ratios (16:9, 4:3)

Try our Ratio Calculator for instant simplification, scaling, and conversion.