If percentages, per mills and parts per million still confuse you, give this PPM calculator a shot. It is a simple tool that can be used for conversion from PPM to units such as percents or parts per billion (PPB). In this article, we will provide you with a short description of each of the proportion metrics and give you a detailed explanation of how to calculate PPM and percentages.

How to calculate PPM and percents

All of the proportion metrics are quite similar: they describe small values of dimensionless quantities, such as the volumetric proportion of NO₂ in the air. For example, PPM means "parts per million". If you find out that the concentration of NO₂ is equal to 1 ppm, it means that if you take a 'sample' of air and divide it into a million parts, one of them will consist of NO₂.

The proportion metrics are as follows:

  • Percentage: equal to 1 per 100
  • Permille: equal to 1 per 1,000
  • PPM: equal to 1 per 1,000,000
  • PPB: equal to 1 per 1,000,000,000
  • PPT: equal to 1 per 1,000,000,000,000

PPM conversion: an example

Let's take the following example: you have created a solution of salt (NaCl) in water. You used 0.005 grams of salt, and the final mass of the solution is equal to 1 kilogram. How many parts per million (PPM) of salt are in the solution?

  1. Start with expressing the solution concentration as a decimal. There are 0.005 grams of salt in 1 kilogram (1000 grams). It means that the decimal is equal to

0.005 / 1000 = 0.000005

  1. To find the percentage, multiply this value by a hundred:

0.000005 * 100 % = 0.0005

  1. To find the permille value, multiply the decimal by a thousand:

0.000005 * 1,000 ‰ = 0.005

  1. For the PPM, multiply the decimal by a million:

0.000005 * 1,000,000 PPM = 5 PPM

  1. Finally, for the PPB, multiply the decimal by a billion:

0.000005 * 1,000,000,000 PPB = 5 PPB

Bogna Haponiuk