Everyday Tools

Inverse Proportion Calculator

Solve a basic inverse proportion by leaving one value blank in a constant-product relationship.

Updated April 16, 2026
Free online tool
Planning and research use

Why this page exists

Inverse-relationship problems get easier when the constant product can be solved directly instead of being rearranged by hand each time. This calculator helps visitors solve a simple inverse proportion by filling in three values and leaving one blank in a constant-product setup.

Interactive tool

Run the estimate

Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.

Calculator

Inverse proportion calculator

Solve a basic inverse-proportion equation by leaving one value blank in x1 x y1 = x2 x y2.

Result

y2 = 8

Estimated missing inverse-proportion value using the constant-product relationship x1 x y1 = x2 x y2.

Solved missing valuey2 = 8

Completed inverse relationship4 x 12 = 6 x 8

Values usedx1=4, y1=12, x2=6, y2=8

Constant-product check48 = 48

Solving 4 x 12 = 6 x 8 gives y2 = 8 in this inverse-proportion setup.
The completed relationship is valid because both sides share the same constant product after the missing value is solved.
Use this for inverse-relationship problems only, because the calculator expects one missing value in a simple constant-product setup.

This is standard inverse-proportion math. The calculator expects exactly one missing value and uses a constant-product relationship on one consistent basis.

Planning note

Last updated April 16, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.

How it works

What the calculator is doing

Enter three values and leave one field blank.

The calculator treats the relationship as x1 times y1 equals x2 times y2.

It solves the missing value and shows the completed inverse relationship.

Understanding your result

This is standard inverse-proportion math. The calculator expects exactly one missing value and uses a constant-product relationship rather than a direct ratio.

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Examples

Ways people use this tool

Example scenarios help turn a quick estimate into a more useful comparison or planning step.

Solve a simple inverse-relationship worksheet problem

This is useful when one quantity goes up while the other goes down and the product stays constant.

Check a classroom or homework answer

A completed constant-product relationship can make it easier to verify the algebra quickly.

Compare with direct proportion

Seeing the inverse setup beside a direct proportion can help clarify when the two methods are different.

FAQ

Common questions

How does this calculator solve the missing value?

It uses the constant-product relationship for inverse proportion, where x1 times y1 equals x2 times y2.

Why do I need to leave only one field blank?

Because the calculator needs three known values to solve the fourth value cleanly in one inverse relationship.

How is this different from the proportion calculator?

The proportion calculator uses direct cross multiplication, while this tool uses a constant-product inverse relationship.

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Keep comparing

Use these related tools to compare nearby scenarios, check a second estimate, or keep narrowing down the right decision.

Everyday ToolsUpdated April 16, 2026