Find the percentage increase or decrease between two numbers — enter a starting value and an ending value.
Percentage change measures how much a value has grown or shrunk, relative to where it started. It answers questions like "my rent went from $1,200 to $1,380 — how much more is that in percentage terms?" The answer, 15%, is far more useful than the raw $180 difference because it lets you compare changes of very different sizes on the same scale.
The key is the base: percentage change is always measured against the original value, not the new one. That is why the calculation is not symmetric. A stock that rises from $100 to $150 has gained 50%, but falling from $150 back to $100 is only a 33% drop — the base changed from 100 to 150.
If the new value is larger than the old one, the result is positive — an increase. If it is smaller, the result is negative — a decrease. This single formula handles both; the sign tells you the direction. A result of 0% means no change at all.
Percentage change is everywhere: price rises and sale discounts, salary raises, population growth, investment returns, exam-score improvements, and month-over-month business metrics. Whenever you need to express "how much bigger or smaller" in a way that scales, this is the calculation to reach for. For finding a percentage of a number instead, use the percentage calculator.
Subtract the old value from the new value, divide by the old value, then multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25% increase.
Use the same formula — a negative result means a decrease. From 100 to 80: (80 − 100) ÷ 100 × 100 = −20%, i.e. a 20% decrease.
Percentage change compares the difference to the starting value. Percentage points are the plain arithmetic gap between two rates: going from 10% to 15% is +5 percentage points but a 50% increase.
A 25% increase followed by a 25% decrease does not return the original number, because each percentage is taken from a different base. 100 → +25% = 125 → −25% = 93.75.
Yes. If a value more than doubles, the increase exceeds 100%. From 50 to 150 is a 200% increase, because the change (100) is twice the original value (50).