Percentage Increase & Decrease Calculator
Apply a chosen percentage increase or decrease to an original value and see the change amount and resulting value.
How it works
Change amount = original × percentage ÷ 100. For an increase, add the change; for a decrease, subtract it.
Formula / calculation method
change amount = |original| × percentage ÷ 100increase result = original + change amountdecrease result = original − change amount
Worked examples
- Increasing 200 by 10% adds 20 and gives 220.
- Decreasing 200 by 10% subtracts 20 and gives 180.
When this tool helps
Useful for price changes, budgets, growth targets, markdowns, salary adjustments, forecasts, inventory planning, and quick scenario testing.
Related calculations: discount calculator, tip calculator, and markup calculator.
Browse this topic: Percentage, Ratio & Finance Calculators · Percentage & Finance Formula Guide.
Quick reference
| Input | Result |
|---|---|
| 200 + 10% | 220 |
| 200 − 10% | 180 |
| 500 + 5% | 525 |
Accuracy and definitions
The percentage is applied to the original value. A decrease above 100% can produce a negative result, which may be mathematically valid but not meaningful for every real-world quantity.
Methodology & verification
- Method
- Change amount = original × percentage ÷ 100. For an increase, add the change; for a decrease, subtract it.
- Verification
- The displayed formula is cross-checked against Solveberry regression cases before release. Calculator inputs and results stay in the browser.
- Last reviewed
- 2026-08-19
Results are calculated locally in your browser. Optional analytics do not include calculator input values or results.
Common questions
Is a 10% increase followed by a 10% decrease back to the starting value?
No. The second percentage is applied to the new value, so the bases differ.
Can I use this for discounts?
Yes for simple percentage reduction. The dedicated Discount Calculator also shows the amount saved and sale price.
Can I use decimal values?
Yes. The calculator accepts decimal values where they are mathematically valid for the selected calculation.
How should I verify an important result?
Use the displayed formula to reproduce the calculation independently, especially before making financial, legal, engineering or other consequential decisions.