Inverse Proportion Calculator

Work out inverse proportion instantly with clear inputs, formula shown and shareable results.

About Inverse Proportion Calculator

In inverse proportion the product xy is constant, so y = k/x. Doubling x halves y, which is the behaviour of quantities like speed and journey time or workers and time taken.

Formula

Inverse proportion

xy = k, so y₂ = x₁·y₁ / x₂

Worked example

With the default values below, Inverse Proportion Calculator returns Corresponding y of 15.00000000. Change any input above and every figure here is recalculated in your browser.

Inputs used

First x: 6
First y: 20
Second x: 8

Results

Corresponding y: 15.00000000
Constant product k = xy: 120.00000000
x₂ × y₂ (should equal k): 120.00000000
Change in y: -25.0000 %

Step by step

1Values used
2Inverse proportion
3Corresponding y= 15.00000000
4Constant product k = xy= 120.00000000
5x₂ × y₂ (should equal k)= 120.00000000
6Change in y= -25.0000 %

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 8 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

If 6 workers take 20 days, how long do 8 take?

k = 120 worker-days, so 8 workers need 15 days.

Is this always realistic?

It assumes perfect divisibility of the work. In practice coordination overhead means doubling the workforce rarely halves the time exactly.