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Arithmetic Calculator

Ratio & Proportion Calculator

Simplify a two-part ratio and solve a missing fourth value in an equivalent proportion.

Instant answer Formula breakdown Browser-based Mobile friendly
Interactive calculator

Enter your values

Use the example values or replace them with your own. Required validation happens before the calculation.

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Calculated answer

Result

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Simple workflow

How to use the Ratio & Proportion Calculator

Follow these steps to get a reliable result and understand how it was produced.

1

Enter a, b, and c for a : b = c : x.

2

The calculator cross-multiplies the proportion.

3

View x and the simplified ratios.

Understanding the calculation

Cross multiplication converts the proportion into a simple equation. The first ratio is also reduced to lowest whole-number terms where possible.

a : b = c : x, so x = bc/a

The result panel substitutes your numbers into this relationship and shows the important intermediate values.

Common uses

  • Scale drawings and maps
  • Recipes and mixtures
  • Rates, pricing, and resizing

Accuracy tips

  • The first value a cannot be zero.
  • Use values in matching units.
  • Decimals are allowed, though whole values simplify most clearly.
Helpful answers

Ratio & Proportion Calculator FAQs

Important details about formulas, inputs, limitations, and result interpretation.

What is a proportion?

A proportion states that two ratios are equal.

How is the missing value found?

By cross multiplication: a×x = b×c, then x = bc/a.

Can ratios contain decimals?

Yes. The missing value calculation supports decimals.

Does order matter in a ratio?

Yes. Reversing the order changes the meaning of the comparison.

Keep exploring

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Practical tool guide

Using Ratio & Proportion Calculator effectively

Simplify a two-part ratio and solve a missing fourth value in an equivalent proportion. This page is designed to help you calculate a result with a clear browser-based workflow rather than making you install a separate utility for a small task.

How to use it

Enter the known values, select the right unit or formula option, calculate the result, and confirm that the inputs use consistent units.

Best used for
  • quick study calculations
  • everyday numeric checks
  • comparing values and units
What to verify

Double-check units, decimal precision and the values you enter, especially when the result will be used for finance, engineering or other high-impact decisions. Rounding and user-entered values can affect the result. For professional or safety-critical work, verify calculations independently.

Expected: A numerical result based on the values, formula and units selected in the tool. Avoid: Mixing units, percentage points and percentages, or relying on rounded inputs for a high-impact calculation.

Why this workflow matters

A calculator is only as reliable as the values and units entered into it. Use Ratio & Proportion Calculator to speed up routine arithmetic or formula work, then do a quick reasonableness check on the magnitude and sign of the answer. When a calculation affects money, measurements, engineering or another high-impact decision, verify the formula and inputs independently rather than relying on a single automated result.

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