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Percentage Calculator
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X Is Y% of What Number?

Work backwards to the total. When you know a portion and what percentage it represents, this recovers the number it came from — the calculation behind pre-discount prices and pre-tax amounts.

X is Y% of what number?

Enter your numbers and press Calculate — the full working appears here.

The formula

Finding a percentage of a number means multiplying by it. Going the other way means dividing — this calculation simply undoes the multiplication.

Part ÷ (Percentage ÷ 100)

50 ÷ (20 ÷ 100) = 250

Because the percentage is less than 100, the answer is larger than the part you started with.

Worked examples

You paid a $340 deposit, which the agent says is 15% of the total. What is the total?

  1. Turn the percentage into a decimal.15 ÷ 100 = 0.15
  2. Divide the deposit by that decimal.340 ÷ 0.15 ≈ 2,266.67

Answer≈ $2,266.67

Open this example in the calculator →

A jacket cost you $68 after a 15% discount. What was the original price?

  1. Paying after 15% off means you paid 85% of the original.100 − 15 = 85
  2. So $68 is 85% of the original price.68 ÷ 0.85 = 80

Answer$80 before the discount

Open this example in the calculator →

That second example is worth pausing on. Adding 15% back onto $68 gives $78.20, not $80 — the discount was taken off the larger number, so putting it back requires division rather than addition.

Common uses

  • Original prices — recovering the pre-sale price from what you actually paid.
  • Pre-tax amounts — stripping VAT, GST or sales tax out of a gross total.
  • Totals from a deposit — the full cost implied by a percentage paid up front.
  • Sales from commission — the sale value behind a known commission payment.
  • Targets from progress — the full goal when you know how far along you are.
  • Survey populations — the total sample implied by a count and its percentage.

Frequently asked questions

How do I find the whole when I know a percentage of it?
Divide the part by the percentage written as a decimal. If 50 is 20% of a number, then 20% as a decimal is 0.2, and 50 ÷ 0.2 = 250.
50 is 20% of what number?
250. Since 50 represents one fifth of the total, the total must be five times 50.
How do I find the original price before a discount?
If you paid a price after a discount, that price is (100 − discount)% of the original. Paying $68 after 15% off means $68 is 85% of the original, so 68 ÷ 0.85 = $80.
How do I remove sales tax from a total?
A total including 8% tax is 108% of the pre-tax price, so divide by 1.08. A $54 total becomes 54 ÷ 1.08 = $50 before tax. Subtracting 8% from the total instead is a common mistake and gives the wrong answer.
Why can the percentage not be zero?
0% of every number is 0, so if the part were 0% of something, that something could be any number at all. There is no single answer to return.

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