How do you simplify a ratio?

Divide all parts of the ratio by their Greatest Common Factor (GCF). For example, 12:18 simplifies to 2:3 because the GCF of 12 and 18 is 6.

What is the difference between a ratio and a fraction?

A fraction represents a part of a whole, while a ratio compares two or more separate quantities. The ratio 3:5 can be written as the fraction 3/5, but ratios can also compare more than two parts.

How do I solve a missing value in a proportion?

Use cross-multiplication. If A:B = C:D, then A × D = B × C, so D = (B × C) / A.

Can ratios include decimals?

Yes. The simplify section accepts decimal inputs, though ratios are most naturally expressed as whole numbers.

What is a 3-part ratio?

A 3-part ratio compares three quantities simultaneously — for example, mixing paint in a ratio of 1:2:3 means for every 1 part of color A, use 2 of B and 3 of C.

Math

↵ to calculate

Ratio Calculator - Simplify Proportion Online Tool

Simplify ratios, solve for missing values, and compare ratios. Works with 2-part and 3-part ratios.

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How to use this calculator

👉 Fill in the boxes below and your answer appears instantly — no maths needed, we do it all for you! 🎉

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In plain English — what does this do?

🔢 This tool does the maths for you! Just type in your numbers, and it gives you the answer right away. No need to count on your fingers or use a pen and paper.

📌 Direct Answer & Summary

A ratio calculator simplifies ratios to their lowest terms and solves for missing values in proportions. Ratios compare two or more quantities and are widely used in cooking, map reading, finance, engineering, and everyday problem-solving.

Simplify a ratio

: :

Solve for missing value — A : B = C : ?

D (result)

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What is Ratio Calculator - Simplify Proportion Online Tool?

How to use it

1️⃣ To simplify a ratio, enter two or three values in the top section — the simplified form appears instantly.
2️⃣ To solve a proportion (A : B = C : ?), enter A, B, and C in the bottom section to find the missing value D.
3️⃣ The percentage breakdown of each part of the ratio is shown below the simplified result.
4️⃣ Leave the third field blank if you only need a 2-part ratio.

Formula

Simplification: divide all parts by their GCF. Proportion solve: D = (B × C) / A, derived from cross-multiplication of A/B = C/D.

💡 See it in action — a real example

The ratio 6:9 simplifies to 2:3 (GCF is 3). For the proportion 2:3 = 8:?, cross-multiply to get D = (3 × 8) / 2 = 12, so the full ratio is 2:3 = 8:12.

❓ Common questions

How do you simplify a ratio?: Divide all parts of the ratio by their Greatest Common Factor (GCF). For example, 12:18 simplifies to 2:3 because the GCF of 12 and 18 is 6.
What is the difference between a ratio and a fraction?: A fraction represents a part of a whole, while a ratio compares two or more separate quantities. The ratio 3:5 can be written as the fraction 3/5, but ratios can also compare more than two parts.
How do I solve a missing value in a proportion?: Use cross-multiplication. If A:B = C:D, then A × D = B × C, so D = (B × C) / A.
Can ratios include decimals?: Yes. The simplify section accepts decimal inputs, though ratios are most naturally expressed as whole numbers.
What is a 3-part ratio?: A 3-part ratio compares three quantities simultaneously — for example, mixing paint in a ratio of 1:2:3 means for every 1 part of color A, use 2 of B and 3 of C.

⚡ Related Math Tools & Calculators

Percentage Calculator Fraction Calculator GCF Calculator