The Formula
Percentage change = ((New Value − Old Value) ÷ Old Value) × 100
If the result is positive, it's an increase. If negative, it's a decrease. Simple as that.
10 Real-World Examples
| # | Scenario | Calculation | Result |
|---|---|---|---|
| 1 | Salary raised from $50,000 to $54,000 | (54,000−50,000)÷50,000×100 | +8% increase |
| 2 | Price dropped from $120 to $90 | (90−120)÷120×100 | −25% decrease |
| 3 | Test score: 65 to 78 | (78−65)÷65×100 | +20% increase |
| 4 | House price: $280k to $310k | (310−280)÷280×100 | +10.7% increase |
| 5 | Weight: 85 kg to 79 kg | (79−85)÷85×100 | −7.1% decrease |
| 6 | Sales: $8,200 to $11,050 | (11,050−8,200)÷8,200×100 | +34.8% increase |
| 7 | Electricity bill: $180 to $162 | (162−180)÷180×100 | −10% decrease |
| 8 | Inflation: $1.00 to $1.08 | (1.08−1.00)÷1.00×100 | +8% inflation |
| 9 | Followers: 4,200 to 5,040 | (5,040−4,200)÷4,200×100 | +20% increase |
| 10 | Stock: $45.00 to $38.25 | (38.25−45.00)÷45.00×100 | −15% decrease |
Finding the New Value From a Percentage Change
If you know the original value and the percentage change, the new value = Old Value × (1 + percentage/100).
Example: A $60,000 salary with a 7.5% raise: $60,000 × 1.075 = $64,500
Finding the Original Value
If you know the new value and the percentage change, the original = New Value ÷ (1 + percentage/100).
Example: A price is $95 after a 20% discount. Original price = $95 ÷ 0.80 = $118.75
Common Mistakes to Avoid
- Reversibility trap: A 50% increase followed by a 50% decrease does NOT return to the original. $100 → +50% → $150 → −50% → $75. Always apply percentage changes to the current value, not the original.
- Percentage points vs percentages: If an interest rate rises from 3% to 4%, that's an increase of 1 percentage point, but a 33% increase in the rate itself. These are different things.
The percentage calculator below handles all these scenarios — percentage change, finding new values, and working backward from results — in one simple tool.
Calculate any percentage change instantly
Use the free Percentage Calculator on CalcPocket — no signup required.
Percentage Calculator