ounces per cubic inch (oz/in3) to kilograms per liter (kg/L) conversion

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).

$$1\ \text{oz/in3} = 1729.99\ \text{kg/m}^3$$

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 Kilogram per Liter?

The kilogram per liter is a metric unit of mass density, expressing how many kilograms of mass occupy one liter of volume. It is widely used in chemistry, brewing, and everyday contexts because water has a density very close to 1 kg/L.

Definition

One kilogram per liter equals one kilogram of mass distributed over a volume of one liter (one cubic decimeter). Because there are 1000 liters in a cubic meter, the value in SI base units is:

$$1\ \text{kg/L} = 1000\ \text{kg/m}^3$$

Numerically, 1 kg/L is identical to 1 g/mL and to 1 g/cm³, which makes it a convenient bridge between laboratory-scale and bulk measurements.

Origin and History

The unit follows directly from the metric system introduced in France in the 1790s, which defined the gram as the mass of one cubic centimeter of water at its temperature of maximum density (about 4 °C). This deliberate design fixed the density of water at essentially 1 kg/L, and the liter became the standard everyday metric volume.

Law and Notable Facts

The kilogram, liter, and cubic meter are all recognized in the SI (the liter as an accepted non-SI unit). Pure water at 4 °C has a density of about 0.99997 kg/L, historically taken as exactly 1 kg/L, which is why the near-unity value is no coincidence but a founding choice of the metric system.

Real-World Examples and Conversions

Whole cow's milk has a density of roughly 1.03 kg/L. Ethanol is about 0.789 kg/L, so it floats concepts of "lighter than water." Mercury is about 13.6 kg/L. To convert to pounds per US gallon, multiply by 8.345, so water (1 kg/L) is about 8.35 lb/gal.