Understanding ounces per cubic inch to pounds per cubic foot Conversion
The ounce per cubic inch (oz/in³) is a US customary density unit stating avoirdupois ounces of mass per cubic inch. The pound per cubic foot (lb/ft³) is the US customary density unit most common in construction, HVAC, and bulk-material engineering. Since a cubic foot holds 1,728 cubic inches and a pound is 16 ounces, the conversion combines both factors into a clean multiplier of 108 — handy for expressing material densities on the familiar per-cubic-foot basis.
Conversion Formula
To convert ounces per cubic inch to pounds per cubic foot, multiply by this factor:
Step-by-Step Example
Convert 25 ounces per cubic inch to pounds per cubic foot.
How to Convert ounces per cubic inch to pounds per cubic foot
Convert a per-cubic-inch density to the per-cubic-foot basis used in construction.
- Take your oz/in³ value: Note the density figure.
- Multiply by 108: This exact factor combines 1,728 in³/ft³ with 16 oz/lb.
- Record in lb/ft³: The product is the density in pounds per cubic foot.
- Worked result: 25 oz/in³ × 108 = 2,700 lb/ft³.
ounces per cubic inch to pounds per cubic foot conversion table
| ounces per cubic inch (oz/in3) | pounds per cubic foot (lb/ft3) |
|---|---|
| 0 | 0 |
| 1 | 108 |
| 2 | 216 |
| 3 | 324 |
| 4 | 432 |
| 5 | 540 |
| 6 | 648 |
| 7 | 756 |
| 8 | 864 |
| 9 | 972 |
| 10 | 1080 |
| 15 | 1620 |
| 20 | 2160 |
| 25 | 2700 |
| 30 | 3240 |
| 40 | 4320 |
| 50 | 5400 |
| 60 | 6480 |
| 70 | 7560 |
| 80 | 8640 |
| 90 | 9720 |
| 100 | 10800 |
| 150 | 16200 |
| 200 | 21600 |
| 250 | 27000 |
| 300 | 32400 |
| 400 | 43200 |
| 500 | 54000 |
| 600 | 64800 |
| 700 | 75600 |
| 800 | 86400 |
| 900 | 97200 |
| 1000 | 108000 |
| 2000 | 216000 |
| 3000 | 324000 |
| 4000 | 432000 |
| 5000 | 540000 |
| 10000 | 1080000 |
| 25000 | 2700000 |
| 50000 | 5400000 |
| 100000 | 10800000 |
| 250000 | 27000000 |
| 500000 | 54000000 |
| 1000000 | 108000000 |
What is the Ounce per Cubic Inch?
The ounce per cubic inch is a unit of density in the imperial and US customary systems, expressing the mass in avoirdupois ounces contained in one cubic inch of a substance. It is used mainly in engineering and materials work where both mass and volume are stated in customary units.
Definition
One ounce per cubic inch equals the mass of one avoirdupois ounce (28.349523125 g) divided by the volume of one cubic inch (16.387064 cm³).
Because one cubic inch is defined exactly as 16.387064 cm³ and one avoirdupois ounce as exactly 28.349523125 g, the conversion is exact: 1 oz/in³ = 1.72999 g/cm³ = 1729.99 kg/m³. This should not be confused with the fluid-ounce-based densities used for liquids.
Origin and History
The unit derives from the avoirdupois ounce, standardized in England and later fixed to the metric system when the international yard and pound were defined in 1959 (1 pound = 0.45359237 kg exactly, hence 1 ounce = 1/16 pound). Combining this mass with the cubic inch produced a natural density measure for machinists and metallurgists working in inches.
Law and Notable Facts
The ounce per cubic inch is a derived unit with no independent legal definition; it follows automatically from the exact definitions of the avoirdupois ounce and the international inch. Because 1 oz/in³ ≈ 1.73 g/cm³, it produces conveniently sized numbers for dense materials.
Real-World Examples and Conversions
- Water (1.000 g/cm³) is about 0.578 oz/in³.
- Aluminium (2.70 g/cm³) is roughly 1.56 oz/in³.
- Steel (about 7.85 g/cm³) is close to 4.54 oz/in³.
- Lead (11.34 g/cm³) is about 6.55 oz/in³.
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.
Frequently Asked Questions
How many pounds per cubic foot is one ounce per cubic inch?
One ounce per cubic inch equals exactly 108 pounds per cubic foot, since a cubic foot holds 1,728 cubic inches and a pound is 16 ounces (1,728 ÷ 16 = 108).
How do I convert oz/in³ to lb/ft³?
Multiply the oz/in³ value by 108. For example, 0.5 oz/in³ × 108 = 54 lb/ft³.
How do I convert lb/ft³ back to oz/in³?
Multiply the lb/ft³ value by 0.009259259 (which is 1/108). So 108 lb/ft³ = 1 oz/in³.
Why is the factor a neat 108?
It is 1,728 cubic inches per cubic foot divided by 16 ounces per pound, giving exactly 108 with no rounding.
Where is lb/ft³ commonly used?
It is the go-to density unit in US construction, HVAC, and bulk-material work — for example, concrete is about 150 lb/ft³.
People also convert
Complete ounces per cubic inch conversion table
| Unit | Result |
|---|---|
| kilograms per cubic meter (kg/m3) | 1729.994 kg/m3 |
| grams per cubic centimeter (g/cm3) | 1.729994 g/cm3 |
| grams per milliliter (g/mL) | 1.729994 g/mL |
| grams per liter (g/L) | 1729.994 g/L |
| milligrams per milliliter (mg/mL) | 1729.994 mg/mL |
| kilograms per liter (kg/L) | 1.729994 kg/L |
| tonnes per cubic meter (t/m3) | 1.729994 t/m3 |
| pounds per cubic foot (lb/ft3) | 108 lb/ft3 |
| pounds per cubic inch (lb/in3) | 0.0625 lb/in3 |
| pounds per cubic yard (lb/yd3) | 2916 lb/yd3 |
| pounds per US gallon (lb/gal) | 14.4375 lb/gal |
| ounces per US gallon (oz/gal) | 231 oz/gal |
| slugs per cubic foot (slug/ft3) | 3.356743 slug/ft3 |