Percentage calculator

Calculate a percentage of a number, the percent increase or decrease between two values, or the original value from a final value and percentage (reverse percentage).

Choose what you want to calculate first, then fill in the fields below.

Percentage (%)

Base value

Formula: (Value × Percentage) ÷ 100

Old value / start value

New value / end value

Formula: ((New − Old) ÷ Old) × 100 – positive = percent increase, negative = percent decrease.

Type of percentage

Discount (final value is lower) Markup / increase (final value is higher)

Percentage (%)

Final value after discount / markup

Discount: final ÷ (1 − p/100). Markup: final ÷ (1 + p/100).

Result: -

Explanation: No calculation yet.

Calculating with percentages

A percentage is simply “out of one hundred”. For example, 25% means 25 out of 100. The basic percentage formula is:

Value × (Percentage ÷ 100)

With this formula you can do most percentage calculations: calculate a percentage of a number, calculate percent increase or percentage decrease, and find the percentage difference between two values.

Examples for the percentage calculator

• Calculate a percentage of a value: 21% of 100 = 21.
• Calculate percent increase: from 80 to 100 is a 25% increase.
• Percentage decrease calculator: from 100 down to 80 is a 20% decrease.
• Percentage difference calculator: compares two numbers regardless of which is bigger.
• Reverse percentage: you know the final amount after a discount or markup, and want to know the original value.

Use the calculator above as your all-in-one percentage calculator for discounts, markups, taxes, interest and any other situation where you are calculating the percentage or calculating with percentages.