Understanding Pounds per Cubic Inch to Pounds per US Gallon Conversion
The pound per cubic inch (lb/in3) and the pound per US gallon (lb/gal) both use the pound of mass but reference different volumes; a US liquid gallon equals 231 cubic inches. lb/in3 is common for solids and metals, while lb/gal is the working unit for fuels, paints, coatings, and other liquids in the US. This conversion is handy when a material's density is known per cubic inch but you need the pounds-per-gallon figure used in fluid formulation and shipping.
Conversion Formula
To convert pounds per cubic inch to pounds per US gallon, multiply by this factor:
Step-by-Step Example
Convert 25 pounds per cubic inch to pounds per US gallon.
How to Convert Pounds per Cubic Inch to Pounds per US Gallon
The pound stays fixed while the volume scales from a cubic inch to a US gallon.
- Take the density: Begin with your value in pounds per cubic inch, e.g. 25 lb/in3.
- Multiply by 231: A US gallon holds 231 cubic inches, so 1 lb/in3 = 231 lb/gal.
- Compute: 25 × 231 = 5,775.
- Result: 25 lb/in3 equals 5,775 lb/gal.
pounds per cubic inch to pounds per US gallon conversion table
| pounds per cubic inch (lb/in3) | pounds per US gallon (lb/gal) |
|---|---|
| 0 | 0 |
| 1 | 231 |
| 2 | 462 |
| 3 | 693 |
| 4 | 924 |
| 5 | 1155 |
| 6 | 1386 |
| 7 | 1617 |
| 8 | 1848 |
| 9 | 2079 |
| 10 | 2310 |
| 15 | 3465 |
| 20 | 4620 |
| 25 | 5775 |
| 30 | 6930 |
| 40 | 9240 |
| 50 | 11550 |
| 60 | 13860 |
| 70 | 16170 |
| 80 | 18480 |
| 90 | 20790 |
| 100 | 23100 |
| 150 | 34650 |
| 200 | 46200 |
| 250 | 57750 |
| 300 | 69300 |
| 400 | 92400 |
| 500 | 115500 |
| 600 | 138600 |
| 700 | 161700 |
| 800 | 184800 |
| 900 | 207900 |
| 1000 | 231000 |
| 2000 | 462000 |
| 3000 | 693000 |
| 4000 | 924000 |
| 5000 | 1155000 |
| 10000 | 2310000 |
| 25000 | 5775000 |
| 50000 | 11550000 |
| 100000 | 23100000 |
| 250000 | 57750000 |
| 500000 | 115500000 |
| 1000000 | 231000000 |
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.
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.
Frequently Asked Questions
How many pounds per US gallon are in a pound per cubic inch?
Exactly 231 lb/gal, because a US liquid gallon is defined as 231 cubic inches and the pound of mass is the same on both sides.
Does this use the US or imperial gallon?
It uses the US liquid gallon of 231 cubic inches. The imperial gallon is about 20 percent larger and would give a different factor.
How do I reverse it?
Divide the lb/gal value by 231, or multiply by 0.004329004. For example, 231 lb/gal equals 1 lb/in3.
Where is lb/gal most useful?
It is widely used for liquids such as fuels, paints, resins, and coatings, where density per gallon aids formulation, blending, and freight weight calculations.
What is 4 pounds per cubic inch in lb/gal?
Multiply 4 by 231 to get 924 lb/gal.
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Complete pounds per cubic inch conversion table
| Unit | Result |
|---|---|
| kilograms per cubic meter (kg/m3) | 27679.9 kg/m3 |
| grams per cubic centimeter (g/cm3) | 27.6799 g/cm3 |
| grams per milliliter (g/mL) | 27.6799 g/mL |
| grams per liter (g/L) | 27679.9 g/L |
| milligrams per milliliter (mg/mL) | 27679.9 mg/mL |
| kilograms per liter (kg/L) | 27.6799 kg/L |
| tonnes per cubic meter (t/m3) | 27.6799 t/m3 |
| pounds per cubic foot (lb/ft3) | 1728 lb/ft3 |
| pounds per cubic yard (lb/yd3) | 46656 lb/yd3 |
| pounds per US gallon (lb/gal) | 231 lb/gal |
| ounces per cubic inch (oz/in3) | 16 oz/in3 |
| ounces per US gallon (oz/gal) | 3696 oz/gal |
| slugs per cubic foot (slug/ft3) | 53.70788 slug/ft3 |