mg/L to Molarity Converter
Common Conversions
| mg/L | mol/L |
|---|---|
| 1 | 1/(MW×1000) |
| 10 | 10/(MW×1000) |
| 100 | 0.1/MW |
| 1000 | 1/MW |
| 5000 | 5/MW |
| 10000 | 10/MW |
| 50000 | 50/MW |
| 100000 | 100/MW |
| 200000 | 200/MW |
| 500000 | 500/MW |
| 1000000 | 1000/MW |
| 10000000 | 10000/MW |
Why this conversion matters in chemistry
Water-quality and clinical-chemistry analyses report mass concentration in mg/L; reaction stoichiometry runs in mol/L. The bridge is the molar mass — divide mg/L by (MW in g/mol × 1000) to get mol/L. The EPA drinking-water nitrate MCL of 10 mg/L is reported "as N," so dividing by nitrogen's 14.01 g/mol gives 0.71 mmol/L. The same 10 mg/L value reported as the NO₃⁻ ion (MW 62.0) gives only 0.16 mmol/L. The "as N" vs "as NO₃" distinction multiplies through to a ~4× difference, which is why specifying the analyte form matters.
Formula
Worked Examples
1 M NaCl, the textbook reference — well below the ~6 M saturation point of NaCl in water.
1 mM of a 100 g/mol compound — the cleanest illustration of the mg/L → mM shortcut.
1 mM glucose — the value behind a number of metabolic-pathway flux calculations.
5 mM of a 200 g/mol drug — a typical mid-scale assay concentration when the molar mass falls in the small-molecule range.