This mass concentration converter changes the mass of a dissolved substance per volume between kilograms per cubic meter, grams per liter, milligrams per liter, micrograms per liter, ppm, ppb, percent weight per volume and pounds per US gallon. Formula: 1 g/L = 1 kg/m³; 1 mg/mL = 1 g/L. The SI unit is kg/m³, which equals g/L. For dilute solutions in water, 1 mg/L is about 1 ppm and 1 µg/L is about 1 ppb, because a liter of water has a mass of about 1 kg.
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How to use the mass concentration converter
- Enter the value, for example 0.25 mg/L from a water report.
- In the mass concentration converter, choose its unit and the target unit, such as mg/L to µg/L.
- Read the mass concentration converter result: 0.25 mg/L = 250 µg/L.
For mg/L to g/L, divide by 1,000; for µg/L to mg/L, divide by 1,000.
What is mass concentration?
Mass concentration is the mass of a dissolved substance per unit volume of solution, measured in kilograms per cubic meter in SI. Water quality reports usually use milligrams per liter; for dilute water solutions, 1 mg/L is about 1 part per million.
Conversion formula
The mass concentration converter stores every unit as a multiple of the base unit, the kilogram per cubic meter (kg/m³). To convert:
value in target unit = value × (factor of source unit ÷ factor of target unit)
where each factor is the size of the unit in kilograms per cubic meter.
Common mass concentration conversions
| From | To | 1 unit equals |
|---|---|---|
| gram per liter (g/L) | milligram per liter (mg/L) | 1,000 mg/L |
| part per million (ppm) | milligram per liter (mg/L) | 1 mg/L |
| gram per liter (g/L) | kilogram per cubic meter (kg/m³) | 1 kg/m³ |
Mass concentration converter worked example
Convert 25 grams per liter to milligrams per liter:
- Factor of g/L = 1 kg/m³
- Factor of mg/L = 0.001 kg/m³
- 25 × 1 ÷ 0.001 = 25,000 mg/L
Mass concentration unit reference
| Unit | Symbol | Group | Equals (kg/m³) |
|---|---|---|---|
| Kilogram per Cubic Meter | kg/m³ | SI | 1 |
| Gram per Liter | g/L | Common | 1 |
| Milligram per Liter | mg/L | Common | 0.001 |
| Microgram per Liter | µg/L | Common | 1 × 10−6 |
| Part per Million (approx. mg/L in dilute aqueous) | ppm | Common | 0.001 |
| Part per Billion (approx. µg/L in dilute aqueous) | ppb | Common | 1 × 10−6 |
| Percent Weight per Volume (g per 100 mL) | % w/v | Pharmacy | 10 |
| Pound per US Gallon | lb/gal | US | 119.8264273 |
Reverse factors for each mass concentration unit
The mass concentration converter reference table gives each unit in kilogram per cubic meters. To go the other way, divide by that factor; the list below does the division for you.
- Gram per Liter (g/L), Common: 1 g/L = 1 kg/m³, so 1 kg/m³ = 1 g/L.
- Milligram per Liter (mg/L), Common: 1 mg/L = 0.001 kg/m³, so 1 kg/m³ = 1,000 mg/L.
- Microgram per Liter (µg/L), Common: 1 µg/L = 1 × 10−6 kg/m³, so 1 kg/m³ = 1,000,000 µg/L.
- Part per Million (approx. mg/L in dilute aqueous) (ppm), Common: 1 ppm = 0.001 kg/m³, so 1 kg/m³ = 1,000 ppm.
- Part per Billion (approx. µg/L in dilute aqueous) (ppb), Common: 1 ppb = 1 × 10−6 kg/m³, so 1 kg/m³ = 1,000,000 ppb.
- Percent Weight per Volume (g per 100 mL) (% w/v), Pharmacy: 1 % w/v = 10 kg/m³, so 1 kg/m³ = 0.1 % w/v.
- Pound per US Gallon (lb/gal), US: 1 lb/gal = 119.8264 kg/m³, so 1 kg/m³ = 0.008345404 lb/gal.
Drinking water limits in mg/L and ppb
The US EPA sets maximum contaminant levels (MCLs) and action levels in mg/L. In other units:
| Contaminant (EPA limit) | mg/L | µg/L (ppb) | ppm (dilute water) |
|---|---|---|---|
| Arsenic, MCL | 0.01 | 10 | 0.01 |
| Fluoride, MCL | 4 | 4,000 | 4 |
| Nitrate as nitrogen, MCL | 10 | 10,000 | 10 |
| Copper, action level | 1.3 | 1,300 | 1.3 |
Reports may give the same limit in ppb or µg/L; the numbers match for water.
When mg/L equals ppm
ppm by mass is milligrams per kilogram. Converting mg/L to ppm divides by the solution density in kg/L, which is about 1 for dilute water but higher for seawater (about 1.025) or brines. For mass and molar units together, use the molar concentration converter.
Dosing a water tank
Mass concentration is the basis for dosing. To reach 2 mg/L of chlorine in a 1,000 L tank, you need 2 g of available chlorine. Household bleach labeled 6% sodium hypochlorite has about 60 g/L if the percent is weight per volume, so 2 ÷ 60 L ≈ 33 mL. Check the label and local guidance before treating drinking water; strength varies and bleach weakens with age.
Related converters and calculators
Related chemistry tools:
- Molarity converter: mol/L and mmol/L
- Molarity calculator: solutions
- Molecular weight calculator: g/mol
- Density converter: kg/m³ and g/cm³
Sources
NIST Special Publication 811, Appendix B; EPA: National Primary Drinking Water Regulations.
Questions about this calculator
What is the SI unit of mass concentration?
Kilogram per cubic meter (kg/m³), the same as g/L.
How do I convert mg/L to ppm?
For dilute water solutions, 1 mg/L ≈ 1 ppm. For denser liquids, divide mg/L by the density in kg/L.
How do I convert ppm to mg/L?
In dilute water, the value is about the same: 5 ppm ≈ 5 mg/L.
How do I convert mg/L to g/L?
Divide by 1,000. For example, 2,500 mg/L = 2.5 g/L.
What is the EPA limit for arsenic?
The maximum contaminant level is 0.010 mg/L, or 10 µg/L (10 ppb).
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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