Everyone gets very confused when they try to learn how to convert from g/l or mg / l, or mg / g, or something similar, to ppm. However, the process is almost identical to finding a percentage. To find a percentage (parts per hundred), you take the part, and the total and do the following:

percentage of part in total %

To find ppm (parts per million), you take the part, and the total and do the following:

parts per million ppm

Notice any similarities there?

For example, suppose after a fire we have 1 g of carbon in every litre of water in some pond. (I don’t know if this is realistic. Don’t criticise me… =P) We first convert everything to the same units. 1 litre of water is approximately 1000 g. Now, we can find the percentage of carbon in the water:

percentage % %

And the ppm of carbon in the water:

ppm ppm

Simple right?