Mass per volume density.
Pounds per Gallon to Grains per Cup Converter — lb/gal to gr/cup
Convert Pound per Gallon (lb/gal) to Grain per Cup (gr/cup) using the exact conversion factor (1 pound per gallon = 437.5 grain per cup). See the formula, worked examples, conversion table, and common uses.
Pounds per Gallon to Grains 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 119.8264273 / 0.2738889767.
Density uses kilograms per cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Pounds per Gallon to Grains per Cup
Pound per Gallon and Grain 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. Pound per Gallon is most often used for us paint and coatings density specifications.
Formula
grains per cup = pounds per gallon × 437.5
This factor comes from each unit's defined relationship to the category's base unit: 1 pound per gallon equals 119.826427317 base units, and 1 grain per cup equals 0.273888976724 base units, so dividing one by the other gives the direct pound per gallon-to-grain per cup factor of 437.5.
Simple example
1 lb/gal × 437.5 = 437.5 gr/cup
1 pound per gallon = 437.5 grains per cup.
Real-world example
1,000 lb/gal × 437.5 = 437,500 gr/cup
1,000 pounds per gallon = 437,500 grains per cup.
Conversion table
| Pound per Gallon (lb/gal) | Grain per Cup (gr/cup) |
|---|---|
| 0.1 lb/gal | 43.75 gr/cup |
| 1 lb/gal | 437.5 gr/cup |
| 10 lb/gal | 4,375 gr/cup |
| 100 lb/gal | 43,750 gr/cup |
| 1,000 lb/gal | 437,500 gr/cup |
| 10,000 lb/gal | 4,375,000 gr/cup |
Reverse conversion: Grain per Cup to Pound per Gallon
437.5 gr/cup × 0.002285714286 = 1 lb/gal
437.5 grains per cup = 1 pounds per gallon.
pounds per gallon = grains per cup × 0.00228571428571
For a page dedicated to this direction, see Grain per Cup to Pound per Gallon.
Understanding the Pound per Gallon
Pound per Gallon (lb/gal) measures density. The US customary unit for liquid density, based on the US gallon (231 cubic inches). It is classified as a US customary density unit.
Where it's used: United States (paint, fuel, and industrial liquid density specifications)
lb/gal vs. lb/ft³. Both are US customary density units; they're related through the real, fixed relationship between the US gallon and the cubic foot (1 cubic foot ≈ 7.48 US gallons), not a round conversion factor.
Uses of the Pound per Gallon today
- US paint and coatings density specifications
- US fuel and petroleum liquid density specs
- Industrial liquid handling and shipping weight calculations
Understanding the Grain per Cup (gr/cup)
Mass per volume density.
Pound per Gallon — sources
- NIST Handbook 44 — General tables of units including US customary density measures.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many grains per cup are in 1 pound per gallon?
1 pound per gallon equals 437.5 grains per cup, using the exact defined conversion factor rather than an estimate.
How do I convert pound per gallon to grain per cup?
Multiply the pound per gallon value by 437.5. The converter above does this instantly to whatever precision you set.
How do I convert grain per cup back to pound per gallon?
Use the reverse factor: 1 grain per cup equals 0.0022857143 pounds per gallon. You can also use the swap control in the converter above to flip the direction instantly.
What is a pound per gallon?
Pound per Gallon (lb/gal) measures density. The US customary unit for liquid density, based on the US gallon (231 cubic inches). It is classified as a US customary density unit.
What is a grain per cup?
Grain per Cup (gr/cup) is a unit of density.
Is the pound per gallon to grain per cup conversion exact?
Yes. Both pound per gallon and grain per cup are defined by fixed standards rather than physical artifacts, so the factor of 437.5 used above is exact to as many digits as you choose to display.
What is the difference between lb/gal vs. lb/ft³?
Both are US customary density units; they're related through the real, fixed relationship between the US gallon and the cubic foot (1 cubic foot ≈ 7.48 US gallons), not a round conversion factor.
Where is the pound per gallon still used today?
United States (paint, fuel, and industrial liquid density specifications)