How to Use a Ratio Calculator

What the ratio calculator can do

A ratio calculator helps with three related tasks: reducing a ratio, finding a missing value in a proportion, and comparing two ratios. Use it when you want to turn a pair such as 18:24 into a simpler form, solve a relationship such as 2:3 = x:12, or determine which of two ratios is larger.

The tool provides four numeric inputs, A, B, C, and D. It has three modes: Simplify, Missing, and Compare. Simplify is the default mode, so it is ready for reducing the first pair of values unless you choose another operation.

How to use the ratio calculator

1. Enter the values needed for your calculation in A, B, C, and D. For a simple ratio, use A and B. For a proportion, use A, B, and C. For a comparison, enter A, B, C, and D.

2. Select a mode: - Simplify reduces the first pair, A:B. - Missing calculates A × C ÷ B, which gives the missing value in a proportion arranged as A:B = x:C. - Compare evaluates A ÷ B against C ÷ D and reports which ratio is greater, or that neither is greater.

3. Check the values before submitting the calculation. In Simplify mode, the first two values are converted to integers before reduction. In Missing and Compare modes, calculated numeric results are rounded to 10 decimal places.

4. Run the calculation and read the result for the selected mode. If you change from Simplify to Missing or Compare, confirm that the mode control reflects the operation you intend to perform.

Numeric text can be converted when it is valid. Invalid text is ignored, and nonempty text replaces the corresponding numeric value only when the existing value is treated as falsy. If you leave the inputs untouched, their declared starting values are A = 2, B = 3, C = 4, and D = 6.

How to read the result

For Simplify, the result represents the first two inputs after they have been reduced by their greatest common divisor. The second value cannot be zero for this operation.

For Missing, the result is based on A × C ÷ B. Both B and C must be nonzero, because they serve as the relevant divisor and proportion value in this calculation. The displayed numeric result uses rounding to 10 decimal places.

For Compare, the tool evaluates A ÷ B and C ÷ D. It identifies whether the first ratio is greater, the second ratio is greater, or neither is greater. B and D must be nonzero because they are the denominators.

Treat the result as an answer for the selected arrangement of inputs. Changing the order of values changes the calculation, so write the proportion or ratio pairs down before entering them.

Worked example

A student wants to reduce the ratio of 18 red tiles to 24 blue tiles before writing it in a worksheet.

Enter 18 as A and 24 as B, keep Simplify selected, and run the calculation.

The result is a simplified ratio shown as 3:4.

Limitations

• Each operation has input boundaries: Simplify cannot use a zero second value, Missing requires nonzero B and C, and Compare requires nonzero B and D. Missing and Compare numeric results are rounded to 10 decimal places.

Common errors

• A zero value in a required divisor causes the calculation to fail. Replace the zero in B for Missing, or in B or D for Compare; for Simplify, use a nonzero second value.

FAQ

How do I simplify a ratio?

For Simplify, enter the two values in A and B and leave the mode set to Simplify. The tool converts those values to integers and reduces them using their greatest common divisor.

How do I find a missing value in a proportion?

In Missing mode, the calculation is A × C ÷ B. Enter the known values in the arrangement represented by those inputs, and make sure B and C are nonzero.

How can I compare two ratios?

In Compare mode, the tool evaluates A ÷ B and C ÷ D and identifies which ratio is greater, or that neither is greater. B and D must be nonzero.