What This Calculator Does
The constant of proportionality (k) describes the fixed relationship between two variables that vary together, either directly or inversely. This calculator finds k from one known pair of values and uses it to predict y for a new x.
The Formulas
- Direct variation: y = kx, so k = y ÷ x. As x increases, y increases at the same fixed rate.
- Inverse variation: y = k ÷ x, so k = y × x. As x increases, y decreases proportionally.
Once k is known, it stays constant for that relationship, so it can be used to predict y for any new x value (or x for any new y) without needing another pair of measurements. This is a standard algebra and pre-statistics tool for general educational use.
Last reviewed August 2026