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Ratio Calculator

Simplify ratios, solve proportions, scale ratios, and convert to percentages with instant results and visuals.

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What is the Ratio Calculator?

Ratio Calculator helps you simplify ratios, solve proportions (A:B = C:D), scale ratios, and convert them into percentages — all in one fast, no-nonsense tool.

Whether you're working on math homework, mixing ingredients, designing layouts, or analyzing data, this calculator gives you accurate results instantly with helpful visualizations and presets like 16:9 and golden ratio.

How it works

Our Ratio Calculator combines four powerful modes in one intuitive interface:

1. Simplify Mode
Enter 2 or 3 numbers. The tool computes the Greatest Common Divisor (GCD) using the Euclidean algorithm and reduces the ratio to its lowest terms. It also shows equivalent fractions.

2. Proportion Mode
Enter any three values in the form A:B = C:D. The calculator instantly solves for the missing fourth value using cross-multiplication and shows simplified versions of both sides.

3. Scale Mode
Simplify your base ratio first, then apply any positive scale factor. Perfect for scaling recipes, blueprints, or models while preserving proportions.

4. Percentages Mode
See each part of your ratio expressed as a percentage of the total, with a visual bar representation for quick insight.

All calculations happen instantly in your browser. Results include copy buttons for easy sharing and visual proportional bars for better understanding.

Examples

Simplify 12:18

Reduce the ratio to its simplest form

12:18
 
2:3

Solve Proportion

Find the missing value in 5:8 = 15:x

5:8 = 15:x
 
x = 24

Convert to Percentages

Break down 2:3:5 into percentages

2:3:5
 
20% • 30% • 50%

Frequently asked questions

What is a ratio?

A ratio compares two or more quantities and shows their relative sizes. It is usually written in the form A:B or A/B.

How do I simplify a ratio?

Enter the parts of your ratio (2 or 3 numbers). Our tool automatically finds the greatest common divisor (GCD) and divides each part by it to give the simplest form.

What is a proportion?

A proportion states that two ratios are equal (A:B = C:D). Our calculator solves for the missing value when any three numbers are provided.

Can this tool handle 3-part ratios?

Yes. You can simplify ratios with up to 3 parts, scale them, and see percentage breakdowns.

How does the scale feature work?

Enter your ratio and a scale factor (e.g., 2.5). The tool multiplies each part by the factor while keeping the ratio relationship intact.

Why are percentages useful for ratios?

Percentages show the proportional share of each part relative to the total, making it easier to understand distributions (e.g., in recipes, budgets, or mixtures).

Is the calculator accurate for decimals and large numbers?

Yes. It handles decimals and large numbers with proper floating-point precision and rounding for clean display.

Do I need to install anything?

No. Everything runs instantly in your browser with no installation or sign-up required.

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