Understanding Pounds per Cubic Foot to Pounds per Cubic Inch Conversion
The pound per cubic foot (lb/ft3) is a US customary density unit suited to large volumes of building and bulk materials. The pound per cubic inch (lb/in3) keeps the same mass unit but shrinks the volume basis by a factor of 1728, making it the preferred unit for dense metals and compact machined parts. Converting simply rescales density from a foot to an inch reference.
Conversion Formula
To convert pounds per cubic foot to pounds per cubic inch, multiply by this factor:
Step-by-Step Example
Convert 25 pounds per cubic foot to pounds per cubic inch.
How to Convert Pounds per Cubic Foot to Pounds per Cubic Inch
Rescale density from a cubic-foot to a cubic-inch basis while keeping pounds as the mass unit.
- Take the density: For example 25 lb/ft3.
- Divide by 1728: Equivalently, multiply by 0.0005787037 lb/in3 per lb/ft3.
- Compute: Keep about six significant figures.
- Report the result: 25 lb/ft3 x 0.0005787037 = 0.0144676 lb/in3.
pounds per cubic foot to pounds per cubic inch conversion table
| pounds per cubic foot (lb/ft3) | pounds per cubic inch (lb/in3) |
|---|---|
| 0 | 0 |
| 1 | 0.0005787037 |
| 2 | 0.001157407 |
| 3 | 0.001736111 |
| 4 | 0.002314815 |
| 5 | 0.002893519 |
| 6 | 0.003472222 |
| 7 | 0.004050926 |
| 8 | 0.00462963 |
| 9 | 0.005208333 |
| 10 | 0.005787037 |
| 15 | 0.008680556 |
| 20 | 0.01157407 |
| 25 | 0.01446759 |
| 30 | 0.01736111 |
| 40 | 0.02314815 |
| 50 | 0.02893519 |
| 60 | 0.03472222 |
| 70 | 0.04050926 |
| 80 | 0.0462963 |
| 90 | 0.05208333 |
| 100 | 0.05787037 |
| 150 | 0.08680556 |
| 200 | 0.1157407 |
| 250 | 0.1446759 |
| 300 | 0.1736111 |
| 400 | 0.2314815 |
| 500 | 0.2893519 |
| 600 | 0.3472222 |
| 700 | 0.4050926 |
| 800 | 0.462963 |
| 900 | 0.5208333 |
| 1000 | 0.5787037 |
| 2000 | 1.157407 |
| 3000 | 1.736111 |
| 4000 | 2.314815 |
| 5000 | 2.893519 |
| 10000 | 5.787037 |
| 25000 | 14.46759 |
| 50000 | 28.93519 |
| 100000 | 57.87037 |
| 250000 | 144.6759 |
| 500000 | 289.3519 |
| 1000000 | 578.7037 |
What is the Pound per Cubic Foot?
The pound per cubic foot is an imperial and US customary unit of mass density, stating how many avoirdupois pounds of mass fill one cubic foot of volume. It is standard in North American construction, HVAC, and materials engineering.
Definition
One pound per cubic foot equals one avoirdupois pound of mass (0.45359237 kg) distributed through one cubic foot (0.028316846592 m³). Dividing gives:
The relation derives exactly from the defined pound and foot, so the conversion factor 16.018463... kg/m³ is fixed.
Origin and History
The unit grew out of English commercial weights and measures, combining the avoirdupois pound (standardized over centuries and fixed internationally in 1959) with the cubic foot. It persisted in engineering after the US and UK adopted the international pound, remaining entrenched in building codes and product data sheets.
Law and Notable Facts
Under the 1959 international yard and pound agreement, the pound is exactly 0.45359237 kg and the foot exactly 0.3048 m, making lb/ft³ exactly convertible. A useful benchmark: liquid water is about 62.4 lb/ft³, a number engineers memorize for buoyancy and hydrostatic calculations.
Real-World Examples and Conversions
Air at sea level is about 0.075 lb/ft³. Dry softwood lumber runs roughly 25–35 lb/ft³, while concrete is about 150 lb/ft³ and steel about 490 lb/ft³. To convert to kilograms per cubic meter, multiply by 16.0185; to grams per cubic centimeter, divide by 62.43.
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 equal one pound per cubic foot?
One pound per cubic foot equals 0.0005787037 lb/in3, which is exactly 1 divided by 1728.
What is the reverse factor?
Multiply lb/in3 by 1728 to get lb/ft3, since there are 1728 cubic inches in a cubic foot.
Why is the number 1728 involved?
A cubic foot is 12 x 12 x 12 inches, and 12 cubed is 1728, so that is the volume ratio between the two units.
Which materials are quoted in lb/in3?
Dense metals such as steel (about 0.283 lb/in3) and aluminum (about 0.098 lb/in3) are commonly listed in lb/in3 on US engineering tables.
What is 25 lb/ft3 in lb/in3?
It equals 0.0144676 lb/in3.
People also convert
Complete pounds per cubic foot conversion table
| Unit | Result |
|---|---|
| kilograms per cubic meter (kg/m3) | 16.01846 kg/m3 |
| grams per cubic centimeter (g/cm3) | 0.01601846 g/cm3 |
| grams per milliliter (g/mL) | 0.01601846 g/mL |
| grams per liter (g/L) | 16.01846 g/L |
| milligrams per milliliter (mg/mL) | 16.01846 mg/mL |
| kilograms per liter (kg/L) | 0.01601846 kg/L |
| tonnes per cubic meter (t/m3) | 0.01601846 t/m3 |
| pounds per cubic inch (lb/in3) | 0.0005787037 lb/in3 |
| pounds per cubic yard (lb/yd3) | 27 lb/yd3 |
| pounds per US gallon (lb/gal) | 0.1336806 lb/gal |
| ounces per cubic inch (oz/in3) | 0.009259259 oz/in3 |
| ounces per US gallon (oz/gal) | 2.138889 oz/gal |
| slugs per cubic foot (slug/ft3) | 0.03108095 slug/ft3 |