How do I calculate a percentage change?

Percentage change = ((new value - old value) / old value) × 100. A positive result is an increase; a negative result is a decrease. This formula is used for growth rates, price changes, and analytics metrics.

How do I find the original price before a discount?

Divide the sale price by (1 - discount rate). For a 20% discount with a $80 sale price: $80 / 0.80 = $100 original price. This reversal formula is useful for back-calculating original values.

What is the difference between percentage points and percent?

A change from 10% to 15% is a 5 percentage point increase but a 50% relative increase. Percentage points describe absolute changes in a rate; percent describes relative changes.

Percentage Calculation Examples

Percentage calculations appear constantly in e-commerce (discounts), finance (interest rates), and analytics (conversion rates). This collection covers the four most common formulas: finding a percentage of a number, calculating the percentage one number is of another, computing percentage change between two values, and working out the original price before a discount. The percentage calculator handles all four formulas and shows the step-by-step working so you can verify the calculation or use the formula in your code.

Example

# What is 15% of 250?
15% of 250 = 37.5

# 75 is what percent of 300?
75 / 300 × 100 = 25%

# Percentage change from 80 to 100?
(100 - 80) / 80 × 100 = 25% increase

# Price after 20% discount on $120
$120 × (1 - 0.20) = $96.00

# Original price before 30% discount if sale price is $70
$70 / (1 - 0.30) = $100.00

# 8.5% sales tax on $45.99
$45.99 × 0.085 = $3.91

[ open in Percentage Calculator → ]

FAQ

How do I calculate a percentage change?: Percentage change = ((new value - old value) / old value) × 100. A positive result is an increase; a negative result is a decrease. This formula is used for growth rates, price changes, and analytics metrics.
How do I find the original price before a discount?: Divide the sale price by (1 - discount rate). For a 20% discount with a $80 sale price: $80 / 0.80 = $100 original price. This reversal formula is useful for back-calculating original values.
What is the difference between percentage points and percent?: A change from 10% to 15% is a 5 percentage point increase but a 50% relative increase. Percentage points describe absolute changes in a rate; percent describes relative changes.

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