Mass per volume density.
Grains per Fluid ounce to Milligrams per Cup Converter — gr/fl oz to mg/cup
Convert Grain per Fluid ounce (gr/fl oz) to Milligram per Cup (mg/cup) using the exact conversion factor (1 grain per fluid ounce = 518.39128 milligram per cup). See the formula, worked examples, and conversion table.
Grains per Fluid ounce to Milligrams per Cup converter
Converter
Density Converter
Convert thousands of mass-per-volume density combinations for science, engineering, agriculture, and fluids.
Context values
Some unit families need one extra value for a physically accurate result.
Mass per volume density.
Result = input x 2.191111814 / 0.004226752838.
Density uses kilograms per cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Grains per Fluid ounce to Milligrams per Cup
Grain per Fluid ounce and Milligram per Cup both measure density — mass per unit volume — a property used to identify materials, check manufacturing quality, and predict whether something floats or sinks. As a fixed reference point, water has a density of exactly 1000 kg/m³ (1 g/cm³, 1 g/mL) at its temperature of maximum density, which is why many density figures in science and engineering are quoted relative to water. Both are mass per volume density units.
Formula
milligrams per cup = grains per fluid ounce × 518.39128
This factor comes from each unit's defined relationship to the category's base unit: 1 grain per fluid ounce equals 2.19111181379 base units, and 1 milligram per cup equals 0.00422675283773 base units, so dividing one by the other gives the direct grain per fluid ounce-to-milligram per cup factor of 518.39128.
Simple example
1 gr/fl oz × 518.39128 = 518.39128 mg/cup
1 grain per fluid ounce = 518.39128 milligrams per cup.
Real-world example
1,000 gr/fl oz × 518.39128 = 518,391.28 mg/cup
1,000 grains per fluid ounce = 518,391.28 milligrams per cup.
Conversion table
| Grain per Fluid ounce (gr/fl oz) | Milligram per Cup (mg/cup) |
|---|---|
| 0.1 gr/fl oz | 51.839128 mg/cup |
| 1 gr/fl oz | 518.39128 mg/cup |
| 10 gr/fl oz | 5,183.9128 mg/cup |
| 100 gr/fl oz | 51,839.128 mg/cup |
| 1,000 gr/fl oz | 518,391.28 mg/cup |
| 10,000 gr/fl oz | 5,183,912.8 mg/cup |
Reverse conversion: Milligram per Cup to Grain per Fluid ounce
518.39128 mg/cup × 0.001929044794 = 1 gr/fl oz
518.39128 milligrams per cup = 1 grains per fluid ounce.
grains per fluid ounce = milligrams per cup × 0.00192904479412
For a page dedicated to this direction, see Milligram per Cup to Grain per Fluid ounce.
Understanding the Grain per Fluid ounce (gr/fl oz)
Mass per volume density.
Understanding the Milligram per Cup (mg/cup)
Mass per volume density.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many milligrams per cup are in 1 grain per fluid ounce?
1 grain per fluid ounce equals 518.39128 milligrams per cup, using the exact defined conversion factor rather than an estimate.
How do I convert grain per fluid ounce to milligram per cup?
Multiply the grain per fluid ounce value by 518.39128. The converter above does this instantly to whatever precision you set.
How do I convert milligram per cup back to grain per fluid ounce?
Use the reverse factor: 1 milligram per cup equals 0.0019290448 grains per fluid ounce. You can also use the swap control in the converter above to flip the direction instantly.
What is a grain per fluid ounce?
Grain per Fluid ounce (gr/fl oz) is a unit of density.
What is a milligram per cup?
Milligram per Cup (mg/cup) is a unit of density.
Is the grain per fluid ounce to milligram per cup conversion exact?
Yes. Both grain per fluid ounce and milligram per cup are defined by fixed standards rather than physical artifacts, so the factor of 518.39128 used above is exact to as many digits as you choose to display.
What's the difference between density and mass concentration?
Density is the mass of a pure substance or material per unit volume. Mass concentration is the mass of one component — like a dissolved solute — within a mixture's total volume. The two use the same kind of units but describe different physical situations.