ppm and ppb are defined as:
1ppm = 1/106 = 10-6
1ppb = 1/109 = 10-9
So
1ppm = 1000ppb
The number of parts-per billion xppb is equal to the number of parts-per million xppm multiplied by 1000:
xppb = xppm ⋅ 1000
Example: 7ppm is equal to 7000ppb:
xppb = 7ppm ⋅ 1000 = 7000ppb
| ppm | ppb |
|---|---|
| 0.001 | 1 |
| 0.01 | 10 |
| 0.1 | 100 |
| 1 | 1000 |
| 10 | 10000 |
| 100 | 100000 |
| 1000 | 1000000 |
| 10000 | 10000000 |