Percentage Calculator
Find a percentage, compare two values, measure a change, or recover the original amount.
Last updated: November 4, 2026
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Quick summary: Find a percentage, compare two values, measure a change, or recover the original amount.
Read the complete guide
Updated reference sections in this guide are in English.
Choose the question first
These four calculations use the same two input boxes in different ways. Select the question before entering values: the labels change to show which number belongs in each box. A percentage expresses a value relative to a reference amount; identifying that reference is the most important step.
- Percent of a number: enter the percentage and the number it applies to.
- Part as a percentage: enter the part first, followed by the positive reference total.
- Percentage change: enter the positive original value first and the new value second.
- Recover the original: enter the percentage change and the value after that change. Use a negative change for a decrease.
The four formulas
Part as a percentage = part ÷ reference total × 100
Percentage change = (new − original) ÷ original × 100
Original value = new ÷ (1 + change ÷ 100)
The result is a plain amount for the first and fourth questions, and a percentage for the second and third. The calculator displays the arithmetic used so you can check the denominator rather than relying on a number without context.
Examples you can reproduce
A discount amount
20% of 250 is 20 ÷ 100 × 250 = 50. This is the amount taken off, not the discounted selling price. Subtract 50 from 250 to get 200.
An increase and its reverse
A value rising from 80 to 100 increases by (100 − 80) ÷ 80 × 100 = 25%. Returning from 100 to 80 is a 20% decrease, because the reference value is now 100.
Recovering a price before a decrease
If 80 is the value after a 20% reduction, select the original-value question, enter −20 and 80. The original is 80 ÷ 0.8 = 100.
Check this scenario in the calculator:
- What would you like to calculate?
- X percent of a number
- Percentage (%)
- 20
- Number
- 250
Percentages are not percentage points
If a rate changes from 10% to 15%, the difference is 5 percentage points. Its relative increase is (15 − 10) ÷ 10 × 100 = 50%. Those statements answer different questions. This tool calculates the relative change when you enter 10 and 15; it does not label that result as percentage points.
Boundaries and common errors
The part-as-percentage question needs a positive reference total. The change question needs a positive original value, so it does not assign a misleading growth rate to zero or a negative starting balance. Recovering an original value requires a change greater than −100% and a nonnegative final amount. A 100% decrease loses the information needed to reconstruct the original. Values are calculated at full browser precision and then formatted for display.
Questions about percentages
Can a percentage be above 100%?
Yes. A part can be larger than its reference total. For example, 150 relative to 100 is 150%.
Why does a 20% increase followed by a 20% decrease not cancel out?
The second change uses a different base: 100 × 1.2 × 0.8 = 96, a net decrease of 4%.
Can I type Arabic digits?
Yes. Arabic and Persian digits and the Arabic decimal mark are accepted. Use no thousands separators; a comma is not treated as a decimal mark.