ppm和ppt定义为：
1ppm = 1/10 6 = 10 -6
1ppt = 1/10 12 = 10 -12
所以
1ppm = 10 6个百分点
每百万分之几x ppm等于每万亿分之几x ppt除以10 6：
x pp m = x pp t / 10 6
例如：7000ppt等于0.007000ppm：
x ppt = 7000ppt / 10 6 = 0.007ppm
| ppt | ppm |
|---|---|
| 1 | 0.000001 |
| 10 | 0.00001 |
| 100 | 0.0001 |
| 1000 | 0.001 |
| 10000 | 0.01 |
| 100000 | 0.1 |
| 10 6 | 1 |
| 10 7 | 10 |
| 10 8 | 100 |
| 10 9 | 1000 |
| 10 10 | 10000 |