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Percentage calculator

Find a percentage of a number, apply increase or decrease, work out ratios and percentage change — all in one tool.

Percent of a number

Enter percent
Enter base number
Example
18% of 250 = 45

Apply percentage increase

Enter number to increase
Enter increase percentage
Example
100 + 2% = 102

Apply percentage decrease

Enter number to decrease
Enter decrease percentage
Example
100 - 20% = 80

What percentage is A of B?

Enter number to compare
Enter reference number
Example
21 of 140 = 15%

Percentage change

Enter end value
Enter start value
Example
From 50 to 75 = +50% change

What is a percentage?

A percentage is "out of 100". So 20% is 20 per 100, or 0.2. Use it to compare sizes or describe how something changes.

You’ll see percentages in discounts, marks, statistics and things like price or population changes.

Basic formulae

  • Part of whole: Part = Total × % / 100.
  • Percentage: % = (Part / Total) × 100.
  • Increase: End = Start × (1 + %/100).
  • Decrease: End = Start × (1 − %/100).
  • Change rate: ((End − Start) / Start) × 100.

Short method

First decide whether you are calculating a part of a whole or a change between two values, then apply the right formulae.

Handy shortcuts: 10% = ÷10, 5% = half of 10%, 20% = twice 10%.

Percentage vs percentage points

Don’t mix up "+3 percentage points" and "+3%". Going from 10% to 13% is +3 points, but a 30% relative increase.

Example calculations

18% of 250 = 45.

Discount: 60 − 20% = 48.

Increase: 40 → 50 = +25%.

Part: 24 of 120 = 20%.

Change rate: 80 → 100 = ((100−80)/80) × 100 = 25%.

Quick reference

  • 1% = 1/100 of the whole.
  • 5% = 1/20 of the whole.
  • 25% = 1/4 of the whole.
  • 50% = half of the whole.
  • 75% = three quarters of the whole.

Where you’ll use percentages

  • Sale prices, VAT, promotions and discounts.
  • Marks, averages and school or exam results.
  • Budgets, statistics and data over time.
  • Shares of a total (e.g. market share, survey results).

Common mistakes

  • Mixing up "part of a whole" and "change from one value to another".
  • Omitting ÷100 when turning a percentage into a decimal.
  • Applying the % to the wrong starting value.
  • Treating a "percentage point" change as if it were a "%" change.

Common questions

  • "Increase" vs "% of a total"? One is change between two values; the other is a share of one value.
  • Unexpected result? Check if you want a share, a new value after increase/decrease, or a change rate.
  • For a full breakdown (formulae and reasoning), use the solver on the home page.