Percentage Change Calculator — Increase & Decrease Formula

⚡ QUICK ANSWER

Percentage change formula: % = ((New Value − Old Value) ÷ Old Value) × 100. Positive result = increase. Negative result = decrease. Example: from $80 to $100 → ((100−80)÷80)×100 = +25%.

How to Calculate Percentage Change — 3 Steps

Subtract: New Value − Old Value$120 − $100 = $20 (the change amount).

Divide by the Old Value$20 ÷ $100 = 0.20

Multiply by 100 to get the percentage0.20 × 100 = +20% increase. If the result is negative, it's a decrease.

Percentage Change Formula — Both Directions

Situation	Formula	Example
Price increase	((New−Old)÷Old)×100	$80→$100 = +25%
Price decrease	((New−Old)÷Old)×100	$100→$80 = −20%
Salary raise	((New−Old)÷Old)×100	$14k→$16k = +14.3%
Discount amount	((Sale−Original)÷Original)×100	$60→$45 = −25%

12 Percentage Change Examples

$50 → $75

+50%

$200 → $150

−25%

$14,000 → $16,100

+15%

100 → 85

−15%

$8.50 → $9.35

+10%

$1,200 → $900

−25%

50 → 73

+46%

$25 → $30

+20%

300 → 270

−10%

$45 → $36

−20%

$60 → $78

+30%

500 → 425

−15%

Percentage Change vs Percentage Difference

These are NOT the same thing. Percentage change measures how much one value changed relative to the starting value — it has a direction (increase or decrease). Percentage difference compares two values without a "start" or "end" — useful when neither value is the reference point. For comparing prices at two different stores, use percentage difference. For tracking how a price evolved over time, use percentage change.

Common Mistakes

Using the wrong base: always divide by the OLD value, not the new one. From $80 to $100: divide by 80, not 100.
Confusing percentage points with percent change: if a rate goes from 4% to 6%, it increased by 2 percentage points but by 50% in relative terms.
Adding percentages: +20% followed by −20% does NOT return to the original. $100 → $120 → $96 (not $100).