Calculate shrinkage percentage from original and final measurements, or find the final or original size from a shrink rate, in any length unit.

Compare a positive original measurement with a nonnegative final measurement.

Shrink is measured relative to the original value. A negative shrink rate means growth; these formulas do not predict a material’s actual shrinkage.

Related Calculators

Shrink Percentage Formula

The following equation uses the original measurement as the denominator. Compare the same type of quantity in compatible units, converting length units before subtracting. Unitless inputs must be compared with unitless inputs, not mixed with a physical length.

S = (OS - FS) / OS × 100
  • Where S is the shrink percentage (%)
  • OS is the original measurement, which must be greater than zero
  • FS is the final measurement, which must be nonnegative and may exceed OS when there is growth

Subtract final from original, divide by original, and multiply by 100. For an entered percentage p, final = original × (1 − p / 100), and original = final / (1 − p / 100) when that gives a unique positive original. At p = 100%, final must be zero: zero final leaves the original indeterminate, while nonzero final is impossible. With zero final and p below 100%, there is no positive original. Rates above 100% are outside this nonnegative-measurement model.

What is a Shrink Percentage?

Definition:

Shrink percentage is signed change relative to the original measurement. A positive result indicates a decrease, zero indicates no change, and a negative result indicates growth. A 100% decrease means a zero final measurement. The original must remain positive because division by an original measurement of zero is undefined.

How to Calculate Shrink Percentage?

Example Problem:

The following example outlines the steps and information needed to calculate Shrink Percentage.

First, determine the original size of the object. In this example, we are looking at the change in size of the length of a rod. For this example, the original length was 10 inches.

Next, determine the final size after shrinking. After shrinking the final size is measured to be 8 inches.

Finally, calculate the shrink percentage using the formula above:

S% = (OS-FS) / OS * 100

S% = (10-8) / 10 * 100

S% = 20%