Ratio Calculator accuracy and testing

Formula source

• The calculator uses the **Cross-Multiplication** rule: If $\frac{A}{B} = \frac{C}{D}$, then $A \times D = B \times C$. To solve for any missing variable (e.g., D), rearrange the formula: $D = \frac{B \times C}{A}$.

Test cases

Known limitations

• This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
• Use the result as a planning estimate unless the calculator page states a stricter purpose.

Assumptions

• The values in each ratio should describe the same kind of quantity, such as width-to-height or cups-to-eggs.
• The relationship is treated as linear, so the same scale factor applies across both ratios.
• A value used as a denominator cannot be zero; zero makes the proportion undefined.

Unit handling

• A accepts numeric values.
• B accepts numeric values.
• C accepts numeric values.
• D accepts numeric values.
• Solve For accepts one of the configured options.

Rounding rules

• Number displays use up to 2 decimal places in the calculator UI.

Version history

Change log