Find Percent Change
Enter an original value and a new value to see the percentage increase or decrease.
Apply Increase/Decrease
Start with a value, choose increase or decrease, and apply a percentage.
What this percentage increase and decrease calculator does
This tool gives you two fast ways to work with percentages:
- Percent change calculator: Compare an original amount and a new amount to find whether the result is an increase or decrease.
- Increase/decrease calculator: Apply a known percentage to a starting value to get the final value.
It is useful for discounts, salary changes, revenue growth, stock moves, budgeting, and everyday price comparisons.
Percentage increase and decrease formulas
1) Percentage change between two values
Percentage Change = ((New Value − Original Value) ÷ Original Value) × 100
If the result is positive, it is a percentage increase. If negative, it is a percentage decrease.
2) Final value after increase or decrease
- Increase: Final Value = Starting Value × (1 + Percentage ÷ 100)
- Decrease: Final Value = Starting Value × (1 − Percentage ÷ 100)
Worked examples
Example A: Price drop (percentage decrease)
A jacket goes from $80 to $60.
Change = 60 − 80 = −20. Then (−20 ÷ 80) × 100 = −25%.
So the jacket price decreased by 25%.
Example B: Salary raise (percentage increase)
Salary goes from $50,000 to $55,000.
Change = 55,000 − 50,000 = 5,000. Then (5,000 ÷ 50,000) × 100 = 10%.
So salary increased by 10%.
Example C: Applying a discount directly
A product costs $120 and has a 15% discount.
Final price = 120 × (1 − 0.15) = 120 × 0.85 = $102.
Common mistakes to avoid
- Using the wrong base: Always divide by the original value when finding percent change.
- Ignoring sign direction: Positive means increase, negative means decrease.
- Assuming reverse percentages cancel: A 20% decrease followed by a 20% increase does not return to the same value.
- Confusing percentage points with percent: Going from 10% to 15% is a 5 percentage-point change, but a 50% relative increase.
Why percent change matters in real life
Understanding percentage increase and percentage decrease helps you make better decisions in finance and planning. You can compare growth rates between months, measure the impact of marketing campaigns, analyze investment returns, and verify whether a sale price is actually a good deal.
For students, this calculator makes percent change practice easy. For professionals, it saves time when reviewing reports, invoices, budgets, and performance dashboards.
Quick FAQ
Can I use negative values?
Yes. The calculator accepts negative numbers, which can be useful in accounting or data analysis contexts.
What if the original value is zero?
Standard percentage change cannot be computed when the original value is zero, because division by zero is undefined. The calculator will show a helpful message in that case.
Is this the same as a discount calculator?
Partly. The increase/decrease section can calculate discounts directly, but this page also covers general percent increase formula and percent decrease formula use cases.
Final tip
When evaluating any change, always ask: “Change relative to what starting point?” That one question prevents most percentage errors.