Percentage Increase Calculator
Use this when you know a “before” and “after” number—salary, price, or metric—and want the percentage gain. The old value must be greater than zero.
Percent increase
How this is calculated
Percent increase = ((new − old) ÷ old) × 100. If new is below old, the result is negative (a decrease).
Example: old 80 → new 100 → ((100−80)÷80)×100 = 25% increase.
Use this tool for
- Year-over-year revenue or traffic bumps.
- Tracking a stock or index move from a known cost basis.
- Explaining raise impact relative to prior pay.
Common questions
Why is the answer negative?
A negative percent means the new value fell below the original—use percentage decrease if you prefer wording focused on drops.
Can old be negative?
This UI is aimed at positive baselines (prices, counts). Negative bases flip the intuitive sign of “increase”; use a spreadsheet for those cases.
