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Percentage Change Calculator

Calculate percentage increase or decrease between two values. Perfect for tracking stock prices, growth rates, inflation, and investment returns.

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Percentage Change Calculator | Calculate Increase & Decrease Rates

Calculate percentage increase or decrease between two values. Perfect for tracking stock prices, growth rates, inflation, and investment returns.

Key values: from $45 · to $67 · +48.9%

Inflation: CPI Rise from 280 to 310

The consumer price index rose from 280 to 310. What is the inflation rate?

Key values: CPI 280 → 310 · +10.7% inflation

Documentation

Percentage Change Formula

Percentage Change=New ValueOld ValueOld Value×100%\text{Percentage Change} = \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \times 100\%
  • Positive result = percentage increase
  • Negative result = percentage decrease

The Asymmetry of Percentage Changes

A common trap: percentage increases and decreases are not symmetric.

A stock rises 50% from $100 to $150, then falls 50% — not back to $100, but to $75. The 50% decrease is applied to the new (higher) base. To recover from a 50% loss, you need a 100% gain.

In general, to recover from a p%p\% loss, you need a p100p×100%\frac{p}{100 - p} \times 100\% gain:

LossGain needed to recover
10%11.1%
25%33.3%
50%100%
75%300%
90%900%

Common Applications

  • Financial returns: Stock price changes, portfolio growth
  • Economic indicators: GDP growth, inflation rate, unemployment change
  • Business metrics: Revenue growth, customer churn, conversion rate changes
  • Science: Experimental error, measurement uncertainty

Worked Example

A company's revenue went from $2.4M to $3.1M. What is the percentage change?

3.12.42.4×100%=0.72.4×100%29.2% increase\frac{3.1 - 2.4}{2.4} \times 100\% = \frac{0.7}{2.4} \times 100\% \approx 29.2\% \text{ increase}

Frequently Asked Questions

How do I calculate percentage change?

Use the formula: Percentage Change=((NewOld)/Old)×100\text{Percentage Change} = ((\text{New} - \text{Old}) / \text{Old}) \times 100\\%. A positive result means an increase; a negative result means a decrease.

Why is a 50% loss not recovered by a 50% gain?

Because percentage changes are relative to different bases. A 50% drop from $100 gives $50. A 50% gain on $50 gives only $75, not $100. You need a 100% gain to recover from a 50% loss.

Does it matter which value I use as the old value?

Yes. Always use the original (earlier) value as the denominator. Swapping old and new values gives a different percentage because the base changes. Going from 80 to 100 is a 25% increase, but 100 to 80 is a 20% decrease.

How do I calculate percentage change between negative numbers?

The same formula applies, but interpretation can be tricky. If a company's profit goes from -\\$50 to -\\$20, the change is (20(50))/50×100(-20 - (-50)) / |-50| \times 100\\% = 60\\% improvement. Use the absolute value of the old number as the denominator.

What is the difference between percentage change and percentage point change?

Percentage change is relative (e.g., a rate going from 5% to 6% is a 20% increase). Percentage point change is absolute (the same move is a 1 percentage point increase). The two metrics answer different questions.

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