Percentage Increase Calculator (and Decrease)
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Percentage Increase Calculator
This tool answers two everyday questions: by what percent did a value increase or decrease (from an old number to a new one), and what does a number become after you increase or decrease it by a given percentage. It works for salary raises, price rises, discounts, weight changes, stock moves — any pair of values.
Which percentage tool do I need?
Three tools sound alike but answer different questions:
| Your question | Use this | Example |
|---|---|---|
| How much did a value grow or shrink? (raises, markups, growth) | Percentage Increase / Decrease — this page | 200 → 250 = +25% |
| How did a metric move over time? (prices, stocks, KPIs — with a sign) | Percentage Change | 50 → 60 = +20% |
| How far apart are two independent values? (two quotes, two readings) | Percentage Difference | 40 vs 60 = 40% |
The percentage increase formula
Percentage increase = ((New − Old) ÷ Old) × 100
Example: your salary went from 5,000 to 5,600. The increase is (5,600 − 5,000) ÷ 5,000 × 100 = 12%. If the new value is smaller, the result is negative — that's a percentage decrease.
Increase or decrease a number by a percentage
To increase a number by X%, multiply it by (1 + X ÷ 100); to decrease, multiply by (1 − X ÷ 100). Increasing 80 by 15% gives 80 × 1.15 = 92; decreasing 80 by 15% gives 80 × 0.85 = 68. For prices specifically, the discount calculator also shows the amount you save.
A common trap: increase ≠ decrease
Going from 200 to 250 is a 25% increase, but going back from 250 to 200 is only a 20% decrease — the base of the calculation changes. This is why a 50% loss needs a 100% gain to recover. The calculator always uses the starting value as the base.
Related percentage math
To find what percent one number is of another (rather than the change between them), use the main percentage calculator.
FAQs
Subtract the old value from the new value, divide by the old value, then multiply by 100. For example, from 200 to 250: (250 − 200) ÷ 200 × 100 = a 25% increase.
Percentage increase = ((New value − Old value) ÷ Old value) × 100. If the result is negative, the change is a decrease.
The same formula applies. From 250 down to 200: (200 − 250) ÷ 250 × 100 = −20%, i.e. a 20% decrease. Note the increase and decrease between the same two numbers are not equal percentages.
Enter your old salary as the first value and your new salary (or pay) as the second. For example, a pay raise from 5,000 to 5,600 is (5,600 − 5,000) ÷ 5,000 × 100 = a 12% raise.
Multiply the number by (1 + percentage ÷ 100). To increase 80 by 15%: 80 × 1.15 = 92. Use the "Increase a number by %" mode above.