Percentage Change Calculator
Find the percentage increase or decrease between two values.
Inputs
Allowed range: -1000000000 to 1000000000
Allowed range: -1000000000 to 1000000000
Results
How it works
% change = (new − old) / |old| · 100. Positive = increase, negative = decrease.
Complete guide
Percentage change tells you how much a value grew or shrank relative to where it started. It shows up everywhere — stock returns, salary raises, price changes, audience growth, weight loss.
Formula: (new − old) ÷ |old| × 100. A positive number means an increase; a negative number means a decrease. Going from 50 to 75 is +50%; going from 75 to 50 is −33.3% (not −50% — direction matters).
Don't confuse percentage change with percentage points. If a poll moves from 40% to 45%, that's +5 percentage points but a +12.5% relative change. Headlines often blur this distinction.
Frequently asked questions
- Why is the decrease % smaller than the increase %?
- Because the denominator changes. Going up uses the small starting value; going back down uses the larger ending value. The asymmetry is real, not a calculator quirk.
- What if the old value is zero?
- Percentage change from zero is mathematically undefined (division by zero). Report the absolute change instead.
- Can the result be over 100%?
- Yes. Tripling a value (10 → 30) is a +200% change. There's no upper limit.
- How do I average several percentage changes?
- Don't just average them — compound them. For returns over multiple periods, multiply (1 + r₁)(1 + r₂)... and take the geometric mean.