Understanding Pounds per US Gallon to Pounds per Cubic Inch Conversion
The pound per US gallon (lb/gal) and the pound per cubic inch (lb/in3) both use pounds for mass, so this conversion only rescales volume from gallons to cubic inches. Because a US gallon contains exactly 231 cubic inches, the per-cubic-inch value is a small fraction of the per-gallon figure. This conversion is useful when a liquid density must be compared with the very high per-cubic-inch densities typical of metals and dense solids.
Conversion Formula
To convert Pounds per US gallon to Pounds per cubic inch, multiply by this factor:
Step-by-Step Example
Convert 25 Pounds per US gallon to Pounds per cubic inch.
How to Convert Pounds per US Gallon to Pounds per Cubic Inch
Express a per-gallon density on the per-cubic-inch scale used for dense solids.
- Note the lb/gal value: for example, 25 lb/gal.
- Multiply by 0.004329004: which is 1 divided by 231 cubic inches per gallon.
- Calculate: 25 × 0.004329004 = 0.108225.
- State the result: 25 lb/gal equals 0.108225 lb/in3.
pounds per US gallon to pounds per cubic inch conversion table
| pounds per US gallon (lb/gal) | pounds per cubic inch (lb/in3) |
|---|---|
| 0 | 0 |
| 1 | 0.004329004 |
| 2 | 0.008658009 |
| 3 | 0.01298701 |
| 4 | 0.01731602 |
| 5 | 0.02164502 |
| 6 | 0.02597403 |
| 7 | 0.03030303 |
| 8 | 0.03463203 |
| 9 | 0.03896104 |
| 10 | 0.04329004 |
| 15 | 0.06493506 |
| 20 | 0.08658009 |
| 25 | 0.1082251 |
| 30 | 0.1298701 |
| 40 | 0.1731602 |
| 50 | 0.2164502 |
| 60 | 0.2597403 |
| 70 | 0.3030303 |
| 80 | 0.3463203 |
| 90 | 0.3896104 |
| 100 | 0.4329004 |
| 150 | 0.6493506 |
| 200 | 0.8658009 |
| 250 | 1.082251 |
| 300 | 1.298701 |
| 400 | 1.731602 |
| 500 | 2.164502 |
| 600 | 2.597403 |
| 700 | 3.030303 |
| 800 | 3.463203 |
| 900 | 3.896104 |
| 1000 | 4.329004 |
| 2000 | 8.658009 |
| 3000 | 12.98701 |
| 4000 | 17.31602 |
| 5000 | 21.64502 |
| 10000 | 43.29004 |
| 25000 | 108.2251 |
| 50000 | 216.4502 |
| 100000 | 432.9004 |
| 250000 | 1082.251 |
| 500000 | 2164.502 |
| 1000000 | 4329.004 |
What is the Pound per US Gallon?
The pound per US gallon is a US customary unit of mass density, giving the number of avoirdupois pounds contained in one US liquid gallon. It is widely used for fuels, paints, chemicals, and other liquids sold by the gallon in the United States.
Definition
One pound per US gallon equals one avoirdupois pound (0.45359237 kg) in one US liquid gallon (231 cubic inches, or 3.785411784×10⁻³ m³). The result is:
This uses the US gallon; the imperial (UK) gallon is larger (4.54609 L), so 1 lb per imperial gallon equals about 99.776 kg/m³. Values here refer specifically to the US gallon.
Origin and History
The US gallon descends from the English wine gallon of 231 cubic inches, retained by the United States after Britain redefined its gallon in 1824. Combined with the avoirdupois pound, pounds per US gallon became the standard density and shipping-weight measure for American liquid commerce.
Law and Notable Facts
The US gallon is defined as exactly 231 cubic inches and the pound as exactly 0.45359237 kg, making the conversion exact. A key fact: water weighs about 8.34 lb/gal, the basis of the water-treatment industry's "pounds per million gallons" dosing calculations.
Real-World Examples and Conversions
Water is about 8.34 lb/gal, gasoline roughly 6.0–6.3 lb/gal, and diesel about 7.1 lb/gal. Milk is around 8.6 lb/gal. To convert to kilograms per cubic meter, multiply by 119.826; to kilograms per liter, multiply by 0.119826.
What is the Pound per Cubic Inch?
The pound per cubic inch is a US customary and imperial unit of mass density, giving the number of avoirdupois pounds packed into one cubic inch. Because a cubic inch is tiny, this unit yields large numbers and is reserved for very dense materials such as metals.
Definition
One pound per cubic inch equals one avoirdupois pound (0.45359237 kg) in a volume of one cubic inch (1.6387064×10⁻⁵ m³). The result is:
Since an inch is exactly 0.0254 m and a pound exactly 0.45359237 kg, the factor 27679.9047... kg/m³ is exact.
Origin and History
Like other Anglo-American density units, it combines the avoirdupois pound with the cubic inch, a fine-grained volume long used in machining and metalworking. It became a favored unit in metallurgy and mechanical engineering, where compact, high-density samples are measured.
Law and Notable Facts
The defining pound and inch were fixed exactly by the 1959 international yard and pound agreement. A striking fact: one pound per cubic inch is about 27.68 times the density of water, so almost every everyday liquid has a density well below 0.1 lb/in³, making the unit practical mainly for solids and metals.
Real-World Examples and Conversions
Aluminum is about 0.098 lb/in³, steel about 0.284 lb/in³, lead about 0.410 lb/in³, and gold about 0.698 lb/in³. Water is only about 0.0361 lb/in³. To convert to kilograms per cubic meter, multiply by 27679.9; to grams per cubic centimeter, multiply by 27.6799.
Frequently Asked Questions
How many pounds per cubic inch are in one pound per US gallon?
One pound per US gallon equals 0.004329004 lb/in3. The value is small because a US gallon spans 231 cubic inches.
How do I convert lb/gal to lb/in3?
Multiply the lb/gal value by 0.004329004. A liquid at 12 lb/gal becomes 12 × 0.004329004 = 0.0519480 lb/in3.
What is the reverse factor from lb/in3 to lb/gal?
Multiply lb/in3 by 231, or divide by 0.004329004, to return to pounds per US gallon; the 231 reflects cubic inches per gallon.
Why is the number so small?
Only the volume changes, and one cubic inch is 1/231 of a gallon, so per-cubic-inch density is a tiny fraction of the per-gallon value.
When is lb/in3 useful?
Pounds per cubic inch is the customary unit for dense materials like metals, so converting a liquid density lets you compare it on the same footing.
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Complete pounds per US gallon conversion table
| Unit | Result |
|---|---|
| kilograms per cubic meter (kg/m3) | 119.8264 kg/m3 |
| grams per cubic centimeter (g/cm3) | 0.1198264 g/cm3 |
| grams per milliliter (g/mL) | 0.1198264 g/mL |
| grams per liter (g/L) | 119.8264 g/L |
| milligrams per milliliter (mg/mL) | 119.8264 mg/mL |
| kilograms per liter (kg/L) | 0.1198264 kg/L |
| tonnes per cubic meter (t/m3) | 0.1198264 t/m3 |
| pounds per cubic foot (lb/ft3) | 7.480519 lb/ft3 |
| pounds per cubic inch (lb/in3) | 0.004329004 lb/in3 |
| pounds per cubic yard (lb/yd3) | 201.974 lb/yd3 |
| ounces per cubic inch (oz/in3) | 0.06926407 oz/in3 |
| ounces per US gallon (oz/gal) | 16 oz/gal |
| slugs per cubic foot (slug/ft3) | 0.2325017 slug/ft3 |