Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Percent to Per mille
Convert % to ‰ instantly, then review the formula, assumptions, and rounding guidance.
Chemistry concentration unitsInstant result
Decimals
Formula result = input × 0.01 ÷ 0.001. 1 % = 10 ‰
Common examples
One value, several units
Fraction0.01
Per mille10 ‰
Parts per million10,000 ppm
Parts per billion10,000,000 ppb
Conversion table
| % | ‰ |
|---|---|
| 1 % | 10 ‰ |
| 2 % | 20 ‰ |
| 5 % | 50 ‰ |
| 10 % | 100 ‰ |
| 25 % | 250 ‰ |
| 50 % | 500 ‰ |
| 100 % | 1,000 ‰ |
Conversion chart
1 %10 ‰
5 %50 ‰
10 %100 ‰
25 %250 ‰
50 %500 ‰
Worked example
1% equals 10,000 ppm.
Unit definition
Percent (%) One percent equals 0.01 fraction.
Unit history
Percent is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert % to fraction.
3. Convert the base value to ‰ and apply your display precision.
Important
Mass/volume ppm equivalence depends on solution density.
Understand the result before using it
Percent to Per mille converts a value measured in Percent (%) into the equivalent value in Per mille (‰). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 0.01 ÷ 0.001
Assumptions
- Percent and Per mille represent the same dilute-solution parts quantity.
- The input is expressed in %; the output is expressed in ‰.
- Mass/volume ppm equivalence depends on solution density.
Worked example
1 % = 10 ‰. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a % measurement in a document that expects ‰.
- Compare a percent value with a value reported in per mille.
- Check the %-to-‰ arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- A ppm value is not automatically a mass-per-volume value; the equivalence depends on density and how concentration is defined.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Percent to Per mille?
result = input × 0.01 ÷ 0.001 Using the displayed relationship, 1 % equals 10 ‰.
How many Per mille are in one Percent?
One Percent is 10 Per mille. The displayed digits may be rounded.
Can I reverse the % to ‰ conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts ‰ back to %.
Is the Percent to Per mille result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.