Percentage Calculator
X% of a number, percent change, add or subtract a percentage
Verified against sourcesLast verified 25 September 2026
Your numbers
%
Result
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Tested examples
Every example below is an automated test. Click one to try it.
Formula
- X% of Y = Y × X ÷ 100
- A as a percent of B = A ÷ B × 100
- Percent change = (new − old) ÷ old × 100
- Y ± X% = Y × (1 ± X ÷ 100)
Assumptions
- % means 0.01 (1% = 1 in 100)
- Results are shown to 2 decimal places, rounded half up. The exact value is in the steps.
Sources
NIST
Guide for the Use of the International System of Units (SI), SP 811, §7.10.2accessed 25 September 2026
U.S. Bureau of Labor Statistics
Calculating percent changes (CPI fact sheet)accessed 25 September 2026
Internal reference: reference/01_percentage.md
FAQ
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