661.5 g/kg = 664.741 PSU
| g/kg | PSU |
|---|---|
| 646.5 g/kg | 649.668 |
| 651.5 g/kg | 654.692 |
| 656.5 g/kg | 659.717 |
| 661.5 | 664.741 |
| 666.5 g/kg | 669.766 |
| 671.5 g/kg | 674.79 |
| 676.5 g/kg | 679.815 |
661.5 g/kg = 664.741 PSU
1 g/kg ≈ 1.0049 PSU · 1 mg/L ≈ 0.001 PSU · 1 ppm ≈ 0.001 PSU (dilute aqueous approximation)