CalcArcade.

Percent of a Number Calculator

Enter a percentage and a number to find the amount, plus the totals when you add or subtract that percentage.

Your numbers

Result

How we calculate it

Percent of a number = percentage ÷ 100 × number. Adding the percentage multiplies the number by (1 + p ÷ 100) and subtracting multiplies it by (1 − p ÷ 100).

So 18% of 250 is 45, 250 increased by 18% is 295 and 250 decreased by 18% is 205.

Assumptions and limits

  • Percentages above 100 work too: 150% of 40 is 60.
  • To find the original number before a percentage was added, divide by (1 + p ÷ 100).

Frequently asked questions

How do I find 15% of a number quickly?

Find 10% by moving the decimal one place, then add half of that for the extra 5%. For 80: 8 + 4 = 12.

How do I add a percentage to a number?

Multiply the number by 1 plus the percentage as a decimal. Adding 8% to 50 is 50 × 1.08 = 54.

How do I subtract a percentage?

Multiply the number by 1 minus the percentage as a decimal. A 20% reduction of 50 is 50 × 0.8 = 40.

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Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: Percentage (%) = 18; Number = 250.

  • 18% of 250 45
  • 250 plus 18% 295
  • 250 minus 18% 205

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Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.