Convert mass concentration of a solution between kg/m³, g/L, mg/L, mg/mL and lb/ft³.
Fluids • 6 units
All 6 units on the Solution Concentration Converter are defined against the Kilogram/meter³ (kg/m³), so each result is one conversion factor away from a single reference rather than the end of a chain of roundings.
The conversion this page is most often opened for is ready before you type anything: 1 g/L = 1,000 mg/L. Change either side and every row in the table recalculates with it.
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Four rows in this table are numerically identical, which is the most useful thing to know about it: grams per litre, kilograms per cubic metre and milligrams per millilitre all carry the same number, and milligrams per litre is simply a thousandth of them. A water-treatment figure in mg/L, a process figure in kg/m³ and a laboratory figure in mg/mL can therefore be compared by moving a decimal point, or not moving it at all.
Percentage concentrations are the common source of confusion because three different conventions share one symbol. Mass/volume percent means grams per 100 millilitres, so 0.9% saline is 9 g/L. Mass/mass percent is a true mass fraction and depends on the solution's density before it can be converted to this page's units. Volume/volume percent applies to liquid mixtures such as alcohol solutions and cannot be converted here at all without densities for both components. A bare percentage on a label is under-specified.
Water reports add a convention of their own by expressing hardness and alkalinity as an equivalent mass of calcium carbonate rather than as the ions actually present, so a figure in mg/L as CaCO₃ is not the mass of anything in the sample. Grains per US gallon persists alongside it in American practice, at 17.118 mg/L per grain. Converting a hardness number therefore takes two steps that are easy to collapse into one by mistake: the unit change, and the equivalence basis the laboratory used.
Quick reference — 1 Gram/liter (g/L) is equal to:
| Kilogram/meter³ | kg/m³ | 1 |
| Milligram/liter | mg/L | 1,000 |
| Milligram/milliliter | mg/mL | 1 |
| Gram/milliliter | g/mL | 0.001 |
| Pound/foot³ | lb/ft³ | 0.0624279737 |
6 units of solution concentration, each a fixed multiple of the kg/m³. The table spans 1,000,000:1, from mg/L (0.001 kg/m³) to g/mL (1000 kg/m³). Conversion is one multiplication into the base unit and one division out of it, with no lookup table and no approximation.
value_to = value_from × (factor_from ÷ factor_to)1 kg/m³ = 1 kg/m³1 g/L = 1 kg/m³1 mg/L = 0.001 kg/m³1 mg/mL = 1 kg/m³1 g/mL = 1000 kg/m³1 lb/ft³ = 16.0185 kg/m³where:
Assumptions: Factors are exact definitions. Full double precision is carried internally and rounding is applied only for display.
Result25 g/L = 25000 mg/L
This converter works in mass per unit volume — kilograms per cubic metre in SI, and in practice milligrams per litre, grams per litre and parts per million. It is the language of water treatment, environmental limits and clinical chemistry.
The convenient fact is that in dilute aqueous solution 1 mg/L equals 1 ppm, because a litre of water weighs almost exactly a kilogram. The trap is that this holds for water and not for other solvents, nor for gases, where ppm is normally by volume rather than mass. A "ppm" figure copied from a water report into an air-quality calculation without checking which convention it used is a genuinely common and consequential error.