Percentage Change Calculator

Percentage points versus percent

When the quantity is itself a percentage, be careful with wording. If an interest rate rises from 4% to 5%, it has risen by 1 percentage point, but by 25% in relative terms, because (5 − 4) ÷ 4 = 0.25. News reports often mix these up.

Repeated changes multiply rather than add. A stock that rises 10% one year and falls 10% the next ends at 1.1 × 0.9 = 0.99 of its starting value, a 1% overall loss. To find the average yearly change over several periods, use the compound annual growth rate rather than the simple average of the yearly percentages.

How percentage change is calculated

Percentage change compares a new value with an original one: change = (new − old) ÷ old × 100. A positive result is an increase and a negative result is a decrease. The original value always goes in the denominator, which is why the order matters.

This measure is used for price changes, salary hikes, population growth, exam score improvements and stock movements.

Worked example

Petrol rose from 96 to 104 per litre: (104 − 96) ÷ 96 × 100 = 8.33 percent. If it then falls back to 96, the change is (96 − 104) ÷ 104 × 100 = −7.69 percent. The rise and fall are the same amount in rupees but different percentages, because each is measured against a different starting value.

When to use percentage difference instead

If neither value is the "original" — for example comparing prices in two shops — the percentage difference calculator divides by the average of the two values instead, giving the same answer whichever order you enter them. When the starting value is zero, percentage change is undefined.