Proportions Calculator: Quick and Easy

Use this proportions calculator to solve ratios of the form A : B = C : X. Enter any three values to find the fourth. The calculator can solve any variable. It also shows each step of the method. It is clear and fast. It stays accurate.

How It Works

The calculator uses cross multiplication with ratios. It keeps the rule A times X equals B times C. Enter numbers and leave one field empty. The result fills the blank and updates the full ratio. Results round to six decimal places, then extra zeros drop.

Proportion format: A : B = C : X

How to Use This Tool

Follow these steps to get a clear answer.

1. Decide which value you need.
2. Leave that field empty.
3. Enter the other three numbers.
4. Click Calculate, or type to update the result.
5. Read the Solution box with the ratio and formula.
6. Review the calculation line and the final answer.

What each input means.

• A is the first value on the left ratio.
• B is the second value on the left ratio.
• C is the first value on the right ratio.
• X is the missing value on the right ratio.

Why Use This Proportions Calculator?

It solves any single value from the ratio. You also see the formula and the steps. That helps you learn and check your work.

Instant and Reliable

Results appear as you type or after you press Calculate. You see the ratio and the formula used. You also see the numeric steps and the final line.

• Whole numbers stay whole.
• Decimals round to six places.
• Trailing zeros are removed.

Simple to Use

Keep these notes for smooth results.

• Fill exactly three fields.
• Use digits and a decimal point for decimals.
• A stays nonzero when solving for X.
• B stays nonzero when solving for C.
• C stays nonzero when solving for B.
• X stays nonzero when solving for A.
• Negative values work for algebra checks.

Get Started Today

Try the proportions calculator now. Enter three values and leave one blank. Read the steps and the answer.

Quick example. Set A to 2. Set B to 5. Set C to 8. Leave X blank. The calculator finds X equals 20. It uses X equals B times C over A.

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