655 ppb to ppm

655 ppb = 0.655 ppm

ppbppm
640 ppb0.64
645 ppb0.645
650 ppb0.65
6550.655
660 ppb0.66
665 ppb0.665
670 ppb0.67

655 ppb = 0.655 ppm

Formula

1 ppm = 1 mg/L (aqueous, density ≈ 1 kg/L) · 1 ppb = 0.001 mg/L · 1% = 10,000 ppm