Parts Per Million (ppm)

ppm means "parts per million".

Here is what you need to do the conversions.

1. There are 1000 mg (milligrams) per g (gram) ("milli" means thousandth).

2. There are 1000 µg (micrograms or mcg) per mg (milligram).

3. Because of 1 and 2, there are 1 million (1,000,000) µg (micrograms or mcg) per g (gram) ("micro" means millionth).

**So,**

4. 1 part per million (ppm) for a 1g sample is 1 µg or .001 mg.

(Because there are 1 million micrograms per gram.)

5. 1 part per million (ppm) for a 100g sample is 100 µg or .1 mg.

6. 604 parts per million (ppm) for a 100g sample is 60,400 µg or 60.4 mg.

If the sample size is 100g:

To convert parts per million (ppm) per 100g sample to mg (milligrams), divide by 10.

To convert parts per million (ppm) per 100g sample to µg (micrograms), multiply by 100.

If the sample size is other than 100g:

To convert parts per million (ppm) per X g sample to mg (milligrams), multiply by X and divide by 1000.

To convert parts per million (ppm) per X g sample to µg (micrograms), multiply by X.

For example, if your sample size is 28g, then

5 ppm is 140 µg (micrograms) = 5 x 28

5 ppm is .14 mg (milligrams) = 5 x 28 / 1000