Percent Change Calculator
Calculate the percentage change (increase or decrease) between two values.
How do you calculate percent change?
Formula: ((New Value - Old Value) / Old Value) x 100. Positive = increase, Negative = decrease. Example: Price went from $50 to $65: ((65 - 50) / 50) x 100 = 30% increase. Stock dropped from $100 to $85: ((85 - 100) / 100) x 100 = -15% decrease. Always divide by the starting value, not the ending value.
Why are percentage increases and decreases not symmetrical?
They use different starting points. 50% increase from $100 = $150. But 50% decrease from $150 = $75 (not $100). To reverse a 50% increase, you need a 33.3% decrease (because you're dividing by the larger number). Example: Stock up 100% (doubles) then down 50% = back to original. Up 50% then down 33.3% = back to original.
What is a good percent change for investments?
Context matters: Stock market averages 10% annual gain. 7-8% after inflation is healthy. Short-term: 5-10% in a year is good, 20%+ is excellent, 50%+ is exceptional. Negative returns happen (2022: -18%, 2008: -37%). Real estate typically 3-5% annually. Compare to benchmarks (S&P 500) not absolute numbers.
How do I calculate compound percent changes?
Multiply the decimal forms, not add percentages. Example: 10% increase then 20% increase: 1.10 x 1.20 = 1.32 = 32% total (not 30%). Or: $100 x 1.10 = $110, then $110 x 1.20 = $132. For consecutive 10% increases: 1.10 x 1.10 = 1.21 = 21% total (not 20%). Compounding makes big difference over time.