Parts per million to Milligram/L Converter
Enter the value that you want to convert parts per million (ppm) to milligram/L (mg/L) or milligram/L to parts per million.Also written as PPM to MG/L conversion.
1 parts per million = 1.0000000 milligram/L
Formula: milligram/L = parts per million value × 1.0000000
PPM to MG/L — parts per million to milligram/L
10 parts per million = 10.00000 milligram/L
Popular PPM Converters:
1,000,000 parts
1 PPM
1 part per million
1 mg/L
1 milligram per liter
In water: 1 PPM = 1 mg/L = 1 mg/kg
How Parts per million Relates to Milligram/L
What is Parts per million?
Parts per million (ppm) is a unit of ppm measurement. 1 parts per million is equal to 1.0000000 milligram/L.
About the Milligram/L
Milligram/L (mg/L) is a unit of ppm measurement. 1 milligram/L is equal to 1.0000000 parts per million.
parts per million to milligram/L metric conversion table
| 0.01 ppm | = | 0.01000 mg/L |
| 0.1 ppm | = | 0.10000 mg/L |
| 1 ppm | = | 1.00000 mg/L |
| 2 ppm | = | 2.00000 mg/L |
| 3 ppm | = | 3.00000 mg/L |
| 4 ppm | = | 4.00000 mg/L |
| 5 ppm | = | 5.00000 mg/L |
| 6 ppm | = | 6.00000 mg/L |
| 7 ppm | = | 7.00000 mg/L |
| 8 ppm | = | 8.00000 mg/L |
| 9 ppm | = | 9.00000 mg/L |
| 10 ppm | = | 10.00000 mg/L |
| 11 ppm | = | 11.00000 mg/L |
| 12 ppm | = | 12.00000 mg/L |
| 13 ppm | = | 13.00000 mg/L |
| 14 ppm | = | 14.00000 mg/L |
| 15 ppm | = | 15.00000 mg/L |
| 16 ppm | = | 16.00000 mg/L |
| 17 ppm | = | 17.00000 mg/L |
| 18 ppm | = | 18.00000 mg/L |
| 19 ppm | = | 19.00000 mg/L |
| 20 ppm | = | 20.00000 mg/L |
| 30 ppm | = | 30.00000 mg/L |
| 40 ppm | = | 40.00000 mg/L |
| 50 ppm | = | 50.00000 mg/L |
| 60 ppm | = | 60.00000 mg/L |
| 70 ppm | = | 70.00000 mg/L |
| 80 ppm | = | 80.00000 mg/L |
| 90 ppm | = | 90.00000 mg/L |
| 100 ppm | = | 100.00000 mg/L |
| 200 ppm | = | 200.00000 mg/L |
| 300 ppm | = | 300.00000 mg/L |
| 400 ppm | = | 400.00000 mg/L |
| 500 ppm | = | 500.00000 mg/L |
| 600 ppm | = | 600.00000 mg/L |
| 700 ppm | = | 700.00000 mg/L |
| 800 ppm | = | 800.00000 mg/L |
| 900 ppm | = | 900.00000 mg/L |
| 1000 ppm | = | 1000.00000 mg/L |
How to Convert PPM to MG/L (Parts per million to Milligram/L)?
We can convert parts per million to milligram/L by using an example.
Example:
Convert 20 Parts per million to Milligram/L?
We know 1 Parts per million = 1.0000000 milligram/L; 1 Milligram/L = 1.0000000 parts per million.
20 parts per million = ___mg/L
20 × 1.0000000 = 20.00000 mg/L (we know 1 parts per million = 1.0000000 milligram/L)
Answer:
20 parts per million = 20.00000 milligram/L
How to Convert Parts per million to Milligram/L
- For dilute aqueous solutions, PPM and mg/L are equivalent
- 1 PPM = 1 mg/L (in water at standard conditions)
- Simply use the same numeric value
Formula
Worked Example
Convert 250 PPM to mg/L:
250 PPM = 250 mg/L
250 PPM = 250 mg/L
Parts per million to Milligram/L Conversion Table
| Parts per million (ppm) | Milligram/L (mg/L) |
|---|---|
| 0.1 ppm | 0.1 mg/L |
| 1 ppm | 1 mg/L |
| 5 ppm | 5 mg/L |
| 10 ppm | 10 mg/L |
| 50 ppm | 50 mg/L |
| 100 ppm | 100 mg/L |
| 250 ppm | 250 mg/L |
| 500 ppm | 500 mg/L |
| 1000 ppm | 1000 mg/L |
Technical Details
The equivalence of 1 PPM = 1 mg/L holds for dilute aqueous solutions because the density of water is approximately 1 kg/L at standard temperature and pressure. Since 1 PPM = 1 mg/kg, and 1 kg of water ≈ 1 L, then 1 mg/kg ≈ 1 mg/L. This approximation breaks down for concentrated solutions, non-aqueous solvents, or solutions at extreme temperatures where the density differs significantly from 1 kg/L. In water quality testing, mg/L is the preferred unit for reporting dissolved substances like chlorine, fluoride, nitrates, and heavy metals.
Frequently Asked Questions
Is PPM the same as mg/L?
For dilute water solutions, yes — 1 PPM = 1 mg/L. This is because water has a density of approximately 1 kg/L.
When is PPM not equal to mg/L?
When the solution density is significantly different from 1 kg/L — for example, concentrated salt solutions, organic solvents, or solutions at very high temperatures.
What unit do water treatment plants use?
Most water treatment facilities report in mg/L, which is numerically identical to PPM for water.
How to Convert PPM to mg/L (Parts per Million to Milligrams per Liter)
For dilute aqueous solutions (like drinking water), 1 ppm ≈ 1 mg/L. This approximation holds because water's density is approximately 1 g/mL (1 kg/L), so 1 part per million by mass equals 1 milligram per liter. This equivalence is used universally in water treatment, environmental monitoring, and aquarium chemistry.
- For water and dilute aqueous solutions: ppm ≈ mg/L (direct equivalence).
- The value in ppm numerically equals the value in mg/L.
- This works because water density ≈ 1 kg/L = 1,000 g/L.
- Example: 50 ppm chloride = 50 mg/L chloride in water.
PPM to mg/L: Water Quality Parameters
Drinking water contaminant levels where ppm = mg/L:
| Parts per million | Milligram/L |
|---|---|
| 0.015 ppm | 0.015 mg/L |
| 0.2 ppm | 0.2 mg/L |
| 0.7 ppm | 0.7 mg/L |
| 4 ppm | 4 mg/L |
| 10 ppm | 10 mg/L |
| 250 ppm | 250 mg/L |
| 500 ppm | 500 mg/L |
| 1,000 ppm | 1,000 mg/L |
Solved Examples: PPM to mg/L
Question 1: A well water test shows 7.2 ppm nitrate-nitrogen. Express in mg/L for the EPA comparison.
Solution:
For water: mg/L = ppm (direct equivalence)
7.2 ppm = 7.2 mg/L
Compare to EPA MCL of 10 mg/L (as nitrogen)
Answer: 7.2 ppm = 7.2 mg/L nitrate-N — below the EPA Maximum Contaminant Level of 10 mg/L.
Question 2: An aquarium test kit shows 0.5 ppm ammonia. Convert to mg/L and assess toxicity.
Solution:
For water: mg/L = ppm
0.5 ppm = 0.5 mg/L
At pH 7.0 and 25°C, about 0.5% is toxic un-ionized NH₃
Answer: 0.5 ppm = 0.5 mg/L total ammonia — concerning for fish; begin water changes.
Question 3: Pool water requires 1-3 ppm free chlorine. A test reads 2.4 ppm. Express in mg/L.
Solution:
For water: mg/L = ppm
2.4 ppm = 2.4 mg/L
Within the 1-3 mg/L ideal range
Answer: 2.4 ppm = 2.4 mg/L free chlorine — ideal for pool disinfection.
Practice: PPM to mg/L
Try solving these on your own to test your understanding:
- Convert 8.5 ppm dissolved oxygen to mg/L. (Answer: 8.5 mg/L)
- A water report shows 320 ppm hardness. Express in mg/L. (Answer: 320 mg/L)
- Convert 0.05 ppm arsenic to mg/L. (Answer: 0.05 mg/L)
- Iron content is 0.3 ppm. What is that in mg/L? (Answer: 0.3 mg/L)
- Convert 1,500 ppm TDS to mg/L. (Answer: 1,500 mg/L)
When PPM ≠ mg/L: Non-Aqueous Solutions
The ppm = mg/L equivalence assumes solution density of 1 kg/L. For denser solutions: wastewater with high solids (1.05 kg/L) means 100 ppm = 105 mg/L. Seawater (1.025 kg/L): 35,000 ppm salinity = 35,875 mg/L. For organic solvents: ethanol (0.789 kg/L) gives 100 ppm = 78.9 mg/L. The correction is: mg/L = ppm × density (kg/L). For water quality work this correction is typically ignored since error is < 3%.
Drinking Water Standards: Understanding EPA MCLs
The EPA sets Maximum Contaminant Levels (MCLs) in mg/L (equivalent to ppm for water): lead = 0.015, arsenic = 0.01, fluoride = 4.0, nitrate = 10 (as N), total trihalomethanes = 0.08. Home water test kits report in ppm. Since ppm = mg/L for water, direct comparison to EPA standards is straightforward. If your test shows 0.02 ppm lead, that equals 0.02 mg/L — exceeding the 0.015 mg/L action level.
Key Takeaways
- For water and dilute solutions: 1 ppm = 1 mg/L (numerically equal).
- This equivalence relies on water density being approximately 1 kg/L.
- For denser solutions: mg/L = ppm × density (kg/L).
- EPA drinking water MCLs are in mg/L — directly comparable to ppm test results.
- Gas-phase ppm is volumetric and does not convert to mg/L without molecular weight.
Parts per million to Milligram/L Conversion Formula
milligram/L = parts per million × 1.0000000
1 parts per million = 1.0000000 milligram/L
1 milligram/L = 1.0000000 parts per million
Reverse: parts per million = milligram/L × 1.0000000
Frequently Asked Questions
How many milligram/L are in 1 parts per million?
There are 1.0000000 milligram/L in 1 parts per million. To convert parts per million to milligram/L, multiply the value by 1.0000000.
How do I convert parts per million to milligram/L?
Multiply your parts per million value by 1.0000000 to get the equivalent in milligram/L. For example, 5 parts per million = 5 × 1.0000000 = 5.00000 milligram/L.
How do I convert milligram/L to parts per million?
Multiply your milligram/L value by 1.0000000 to get the equivalent in parts per million. Alternatively, divide by 1.0000000.
What is 10 parts per million in milligram/L?
10 parts per million is equal to 10.00000 milligram/L.
What is 100 parts per million in milligram/L?
100 parts per million is equal to 100.00000 milligram/L.