Inverse Variation Calculator

How it is calculated

For a relationship y = k / x the product of the two quantities never changes. The tool finds that constant from your known pair, k = known_x × known_y, then predicts y = k / new_x. Both results are shown with four decimals. Known x, known y and new x must all be non-zero: a zero in the known pair would make k = 0, which is not a real inverse relationship, and a zero new x would divide by zero, so any of these shows no result. Negative values are accepted and carry their sign through, so a negative known x gives a negative k. The new x must be in the same unit as the known x.

Common mistakes

• Using this for a relationship that is proportional rather than inverse. If y rises when x rises, use direct variation.
• Dividing instead of multiplying to find k. For inverse variation k is x × y, not y / x.
• Assuming the total stays fixed when it does not, for example workers who do not work equally fast or tasks that cannot be split. The model only holds when the product really is constant.
• Mixing units between the pair and the new x, such as days in the pair and hours in the new value.
• Entering 0 in any of the three boxes. A zero known value or a zero new x gives no result, because the relationship has no point at x = 0 and the prediction would be infinite.