Percentage increase, decrease, difference, and change are related but distinct calculations that often get mixed up. This guide walks through each one separately, with formulas and worked examples, so you can tell them apart and use the right one.
Percentage Increase
Use this when a value has grown and you want to know the increase relative to the starting point.
% Increase = ((New Value − Old Value) ÷ Old Value) × 100
Example: a salary rises from $50,000 to $56,000. ((56,000−50,000) ÷ 50,000) × 100 = 12% increase.
Percentage Decrease
Use this when a value has shrunk and you want to know the drop relative to the starting point.
% Decrease = ((Old Value − New Value) ÷ Old Value) × 100
Example: website traffic falls from 12,000 to 9,600 visits. ((12,000−9,600) ÷ 12,000) × 100 = 20% decrease.
Percentage Difference
Use this when comparing two values where neither is clearly the “before” or “after” — for example, comparing two competitors’ prices. It’s calculated relative to the average of the two values, not one specific starting point:
% Difference = (|Value A − Value B| ÷ ((Value A + Value B) ÷ 2)) × 100
Example: Product A costs $40, Product B costs $50. |40−50| ÷ ((40+50)/2) × 100 = 10 ÷ 45 × 100 = 22.2% difference.
Percentage Change
Percentage change is the umbrella term for a directional move from an old value to a new one — it’s the same formula as percentage increase/decrease, just described neutrally:
% Change = ((New Value − Old Value) ÷ Old Value) × 100
A positive number means an increase, a negative number means a decrease.
Increase vs. Decrease vs. Difference vs. Change — Which One Do I Need?
- Comparing a value before and after a rise? Use percentage increase.
- Comparing a value before and after a fall? Use percentage decrease.
- Comparing two unrelated values with no clear “original”? Use percentage difference.
- Want a general term covering either direction? Use percentage change.
Frequently Asked Questions
Q: How do I determine a percentage increase?
A: Subtract the old value from the new value, divide by the old value, then multiply by 100.
Q: Is percentage difference the same as percentage change?
A: No. Percentage change assumes one value is the original and one is the result (directional). Percentage difference treats both values equally and divides by their average, so it has no direction.
Q: Can percentage decrease be more than 100%?
A: No — a decrease is capped at 100% (going from any positive value down to zero). Percentage increase, on the other hand, has no upper limit.
Skip the manual math with our free Percentage Calculator.