変化率計算機

The percentage change calculator helps you calculate percent increase, percent decrease, and the overall percentage change between any two values. Whether tracking stock prices, analyzing data, or calculating discounts, get instant results with step-by-step explanations.

The Percentage Change Formula

The formula for percentage change is:

Percentage Change = ((New Value - Old Value) / Old Value) × 100

A positive result indicates an increase; a negative result indicates a decrease.

Calculating Percent Increase

To find what a value becomes after a percentage increase:

New Value = Original Value × (1 + Percentage/100)

Example: $100 increased by 25% = $100 × 1.25 = $125

Calculating Percent Decrease

To find what a value becomes after a percentage decrease:

New Value = Original Value × (1 - Percentage/100)

Example: $100 decreased by 25% = $100 × 0.75 = $75

Finding the Original Value

If you know the result and the percentage change, find the original:

• After increase: Original = Result ÷ (1 + Percentage/100)
• After decrease: Original = Result ÷ (1 - Percentage/100)

Real-World Applications

• Finance: Stock price changes, investment returns, inflation rates
• Business: Sales growth, cost reductions, profit margins
• Science: Experimental data analysis, population changes
• Shopping: Discounts, markups, price comparisons

Related Calculators

For basic percentage calculations, use our percentage calculator. For discount calculations, try our discount calculator.