663.5 g/kg = 666.751 PSU
| g/kg | PSU |
|---|---|
| 648.5 g/kg | 651.678 |
| 653.5 g/kg | 656.702 |
| 658.5 g/kg | 661.727 |
| 663.5 | 666.751 |
| 668.5 g/kg | 671.776 |
| 673.5 g/kg | 676.8 |
| 678.5 g/kg | 681.825 |
663.5 g/kg = 666.751 PSU
1 g/kg ≈ 1.0049 PSU · 1 mg/L ≈ 0.001 PSU · 1 ppm ≈ 0.001 PSU (dilute aqueous approximation)