Approximate mg/L in water.
Parts per million water to Milligrams per Gallon Converter — ppm to mg/gal
Convert Parts per million water (ppm) to Milligram per Gallon (mg/gal) using the exact conversion factor (1 parts per million water = 3.785411784 milligram per gallon). See the formula, worked examples, and conversion table.
Parts per million water to Milligrams per Gallon converter
Converter
Chemistry Converter
Convert concentration, molarity, amount, and laboratory scientific units by compatible family.
Context values
Some unit families need one extra value for a physically accurate result.
Mass concentration.
Result = input x 0.001 / 0.0002641720524.
Mass Concentration units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Parts per million water to Milligrams per Gallon
Parts per million water and Milligram per Gallon both measure mass concentration — how much of a substance is dissolved or dispersed in a given volume — a core calculation for preparing lab solutions, checking water quality against a regulatory limit, or formulating a pharmaceutical dose. Specifically: Approximate mg/L in water, and mass concentration.
Formula
milligrams per gallon = parts per million water × 3.785411784
This factor comes from each unit's defined relationship to the category's base unit: 1 parts per million water equals 0.001 base units, and 1 milligram per gallon equals 0.000264172052358 base units, so dividing one by the other gives the direct parts per million water-to-milligram per gallon factor of 3.785411784.
Simple example
1 ppm × 3.785411784 = 3.785411784 mg/gal
1 parts per million water = 3.785411784 milligrams per gallon.
Real-world example
100 ppm × 3.785411784 = 378.5411784 mg/gal
100 parts per million water = 378.5411784 milligrams per gallon.
Conversion table
| Parts per million water (ppm) | Milligram per Gallon (mg/gal) |
|---|---|
| 0.001 ppm | 0.0037854118 mg/gal |
| 0.01 ppm | 0.0378541178 mg/gal |
| 0.1 ppm | 0.3785411784 mg/gal |
| 1 ppm | 3.785411784 mg/gal |
| 10 ppm | 37.85411784 mg/gal |
| 100 ppm | 378.5411784 mg/gal |
Reverse conversion: Milligram per Gallon to Parts per million water
3.785411784 mg/gal × 0.2641720524 = 1 ppm
3.785411784 milligrams per gallon = 1 parts per million water.
parts per million water = milligrams per gallon × 0.264172052358
For a page dedicated to this direction, see Milligram per Gallon to Parts per million water.
Understanding the Parts per million water (ppm)
Approximate mg/L in water.
Understanding the Milligram per Gallon (mg/gal)
Mass concentration.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many milligrams per gallon are in 1 parts per million water?
1 parts per million water equals 3.785411784 milligrams per gallon, using the exact defined conversion factor rather than an estimate.
How do I convert parts per million water to milligram per gallon?
Multiply the parts per million water value by 3.785411784. The converter above does this instantly to whatever precision you set.
How do I convert milligram per gallon back to parts per million water?
Use the reverse factor: 1 milligram per gallon equals 0.2641720524 parts per million water. You can also use the swap control in the converter above to flip the direction instantly.
What is a parts per million water?
Parts per million water (ppm) is a unit of chemistry.
What is a milligram per gallon?
Milligram per Gallon (mg/gal) is a unit of chemistry.
Is the parts per million water to milligram per gallon conversion exact?
Yes. Both parts per million water and milligram per gallon are defined by fixed standards rather than physical artifacts, so the factor of 3.785411784 used above is exact to as many digits as you choose to display.
What's the difference between mass concentration and molarity?
Mass concentration expresses how much mass of a substance is present per unit volume (for example, grams per liter). Molarity expresses the amount in moles per liter instead, which accounts for the substance's molecular weight. This category converts mass-concentration units.