PPM in chemistry means parts per million. A measure of the concentration of elements or compounds dispersed in a mixture or solution.

ppm and percentage by weight are based on similar concepts, so you can easily convert from ppm to percentage using the basic conversion formula.


The Formula

PPM to percent formula

Formula: ppm/10,000 copy


Percent to PPM formula

Formula: Percent × 10000 copy



PPM and percentage by weight

Sometimes the Cornell Extension Office explains that, instead of using the terms parts per million, concentrations are reported as a percentage of weight, volume, or molar mass.

A common abbreviation for % by weight is "% w/w". Considering the physical size of the weight, we refer to the proportional measure of the weight of the impurity relative to the total weight.

Recall that sub subjects and multiples of metric units go in degrees of ten hundred thousand. So a milligram is a thousandth of a gram and a gram is a thousandth of a kilogram.

In short, a milligram would be a million (PPM) of a kilogram.
We should already be clear that PPM is a measure of the fit of a compound/solution.

If both the numerator and denominator refer to moles per liter when the quotient is executed, the result will be dimensionless and will be said to be expressed in PPM or as a percentage (%).

When we say that nitrogen in the atmospheric air is 78%, we are not saying that it is m3/m3 for example, it is a measure of proportion and it is dimensionless, so it is with parts per million.



How to convert ppm to percent

We enter the numerical value of the concentration, expressed in PPM units, into the calculator.

For example, if you are converting a value of 300 ppm, you will enter 300. Divide the newly entered value by 10,000. This is the conversion factor between ppm and wt%.

The result of your calculation reports the concentration of the solution, en units, percentage by weight. In the example case, you would divide 300 by 10,000 to get a concentration value of 0.03% (percentage) by weight.

You don't need to multiply by 100% which you would do if your divisor was a million (1,000,000).