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Math • Percentage Change Calculator

Percentage Change Calculator

Calculate the percentage increase or decrease between an old value and a new value.

Percentage Increase
+35.00%
Absolute Difference: +35
Formula: ((New - Old) / |Old|) × 100%
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Calculation Guide & Reference

Percentage Change (Increase / Decrease) Mathematics

Percentage change calculator computes the percent increase or decrease between an old value and a new value, with the exact difference.

Standardized Mathematical Formula
% Change = (New − Old) / Old × 100

Subtracts the old value from the new value, divides by the old value, and converts to a percentage. A positive result is a percentage increase; a negative result is a percentage decrease.

Variables:
Old:Starting (original) value
New:Ending (final) value
How It Works (Step-by-Step)
  • 1Enter the original (old) value and the new value.
  • 2View the raw difference and the percentage change, automatically signed as an increase or decrease.
Real-World Numerical Example
Change from 100 to 135

A value moves from 100 to 135.

•Difference: 135 − 100 = 35.
•Percentage change: 35 / 100 × 100 = 35%.
Result: This is a 35% increase.
Calculation Best Practices & Tips
Examine the discriminant (b² - 4ac) before solving quadratics to instantly know if roots are real, distinct, repeated, or complex.
In statistical analysis, always check both the mean and median to identify if data distribution is skewed by outliers.
When calculating percentage changes, ensure you divide by the original starting baseline value: ((New - Old) / Old) * 100.

Frequently Asked Questions (FAQ)

Subtract the old value from the new value, divide by the old value, then multiply by 100 — a positive result is a percentage increase, a negative result is a percentage decrease.

Because percentage change is always calculated relative to the starting value of that specific step — a 35% increase from 100 to 135, followed by a decrease back to 100, is actually a 25.9% decrease (35/135 × 100), not 35%.

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