Percent Calculator

Reverse Percentage Calculator

To reverse a percentage, divide the known amount by the percent as a decimal. Formula: Whole = Amount ÷ (Percent ÷ 100). Example: 45 is 15% of what? 45 ÷ 0.15 = 300.

Last updated 2026-11-04 · Reviewed by Oguzhan Aydin

Calculate

Known Amount
Percent (%)
%

Original Whole

300

45 ÷ (15 ÷ 100) = 300

% of a numberIncreaseDiscount
Known Amount45
Percent15%
Whole300
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Find the whole when you know a part and its percent

Formula

Whole = Amount ÷ (Percent ÷ 100)

How to calculate a reverse percentage

  1. Enter the known amount (the part you already have).
  2. Enter the percentage that amount represents.
  3. Read the original whole: Amount ÷ (Percent ÷ 100).

Formula:

Whole = Amount ÷ (Percent ÷ 100)

Reference table

AmountPercentWhole
4515%300
2025%80
5010%500

Worked examples

45 is 15% of what?

Result: 300

20 is 25% of what?

Result: 80

12.5 is 5% of what?

Result: 250

Frequently Asked Questions

How do you reverse a percentage?

Divide the known amount by the percent as a decimal. If 45 is 15%, compute 45 ÷ 0.15 = 300.

What if the percent is 0?

The reverse is undefined because you cannot divide by zero.

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