Density Conversion
Free Density conversion Converter for chemical & molecular units. Enter a value to see equivalent measurements across systems.
Density Conversion
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Formula: Converted Value = Input Value x (Source Factor / Target Factor)
Worked example — 7.85 g/cm3 = 490.05 lb/ft3
Formula
Converted Value = Input Value x (Source Factor / Target Factor)
Each density unit has a conversion factor to the SI base unit kg/m3. Multiply the input by the source unit factor to get kg/m3, then divide by the target unit factor to obtain the converted value.
Worked Examples
Example 1: Converting Steel Density to Imperial Units
Problem:Steel has a density of 7.85 g/cm3. Convert this to lb/ft3.
Solution:Base value in kg/m3 = 7.85 x 1000 = 7850 kg/m3 lb/ft3 = 7850 / 16.0185 = 490.05 lb/ft3
Result:7.85 g/cm3 = 490.05 lb/ft3
Example 2: Converting Air Density Units
Problem:Air at sea level has a density of 1.225 kg/m3. What is this in g/cm3?
Solution:g/cm3 = kg/m3 / 1000 g/cm3 = 1.225 / 1000 = 0.001225 g/cm3
Result:1.225 kg/m3 = 0.001225 g/cm3
Frequently Asked Questions
What is density and why does it need to be converted between units?
Density is the mass of a substance per unit volume, typically expressed as mass divided by volume. Different scientific and engineering disciplines use different units for density depending on the context and region. For example, chemists often use grams per cubic centimeter, while engineers in the United States might use pounds per cubic foot. Converting between these units ensures accurate communication and calculation across disciplines and measurement systems.
How is density conversion calculated mathematically?
Density conversion works by first converting the input value to a common base unit (kilograms per cubic meter in SI), then dividing by the conversion factor of the target unit. For example, 1 g/cm3 equals 1000 kg/m3 because there are 1,000,000 cubic centimeters in a cubic meter and 1000 grams in a kilogram. The mathematical relationship is: target value = source value times (source conversion factor divided by target conversion factor).
What is the relationship between g/cm3 and kg/m3?
One gram per cubic centimeter equals exactly 1000 kilograms per cubic meter. This is because converting grams to kilograms divides by 1000, while converting cubic centimeters to cubic meters divides by 1,000,000 (since 1 meter = 100 centimeters and 100 cubed = 1,000,000). The net effect is multiplication by 1000. Water has a density of approximately 1 g/cm3 or 1000 kg/m3 at standard temperature and pressure.
Why is water density used as a reference point in density conversions?
Water at 4 degrees Celsius has a density of exactly 1 g/cm3 (or 1000 kg/m3), which makes it an extremely convenient reference substance. Many density-related measurements, such as specific gravity, are defined relative to water. If a material has a specific gravity of 2.7 (like aluminum), its density is simply 2.7 g/cm3 or 2700 kg/m3. This relationship simplifies many engineering and scientific calculations significantly.
How is density used to check whether an object will float or sink?
An object floats in a fluid if its density is less than the fluid's density, and sinks if its density is greater, which is why ice (about 0.92 g/cm3) floats on liquid water (1.0 g/cm3) while a steel ship hull (around 7.85 g/cm3 for the metal itself) still floats because the ship's overall average density, including the air-filled hull volume, is less than water. This principle, formalized by Archimedes, is why density conversion matters in shipbuilding, submarine ballast design, and even brewing, where hydrometers measure the density of fermenting liquid relative to water to track sugar conversion into alcohol.
What is the difference between density and specific gravity?
Density is an absolute quantity carrying units of mass per unit volume, whereas specific gravity, also called relative density, is the dimensionless ratio of a substance's density to that of a reference material. For liquids and solids the reference is water near 4 degrees Celsius, where its density is essentially 1 g/cm3, which is why specific gravity and density in g/cm3 come out numerically almost identical. Gases are instead referenced to air, so an identical number carries a completely different meaning.
How do temperature and pressure change a measured density?
Solids and liquids expand slightly when heated, so their density falls a small amount as temperature rises, which is why laboratory density values always cite a temperature. Gases are far more sensitive: for an ideal gas, density equals pressure times molar mass divided by the gas constant times absolute temperature, so it falls in proportion to absolute temperature and rises with pressure. Comparing two gas densities is meaningless unless both are quoted at the same stated conditions.
What is the difference between bulk density and true density?
True density, sometimes called particle or skeletal density, is mass divided by the volume of the solid material alone. Bulk density divides the same mass by the total volume the material occupies, including air gaps between and inside the particles, so it is always the smaller number. The gap between them defines porosity, which equals one minus bulk density divided by true density. Soil scientists, powder handlers, and concrete engineers depend on this distinction for compaction and storage calculations.
How do you convert pounds per cubic foot to kilograms per cubic meter?
Multiply the lb/ft3 value by 16.0185 to obtain kg/m3, and divide by that same factor to go back. The factor comes from a pound being 0.45359237 kilograms divided by a cubic foot being about 0.0283168 cubic meters. As a check, water at roughly 62.4 lb/ft3 multiplies out to about 1,000 kg/m3, matching its familiar SI value. Keeping this single factor in mind lets you sanity check any imperial density figure at a glance.
What is API gravity and how does it relate to density?
API gravity is a petroleum industry scale that converts specific gravity measured at 60 degrees Fahrenheit into a more readable number, defined as 141.5 divided by the specific gravity, minus 131.5. Because the relationship is inverted, a lighter oil scores a higher API number while heavy crude scores lower. Water sits at exactly 10 degrees API by construction, so any oil rated above 10 will float on water while anything below it sinks.
References
Background & Theory
1 g/cm3 = 1,000 kg/m3 exactly = 62.4279606 lb/ft3. Water at 4 degrees Celsius sits almost exactly at 1.000 g/cm3, which is the reference point specific gravity is measured against.
Conversion reference table
| Conversion | Equivalent | Exact or rounded? |
|---|---|---|
| 1 gram per cubic centimetre | 1,000 kilograms per cubic metre | Exact by definition |
| 1 g/cm3 | 62.4279606 pounds per cubic foot | Derived, rounded |
| 1 pound per cubic foot | 16.0184634 kilograms per cubic metre | Derived, rounded |
| 1 pound per US gallon | 119.826427 kilograms per cubic metre | Derived, rounded |
| Water at 4 degrees C | 999.972 kg/m3 (about 1.000 g/cm3) | Measured |
| Dry air at 15 C, 1 atm | 1.225 kilograms per cubic metre | Standard atmosphere |
| 1 kg/m3 | 0.001 g/cm3 | Exact |
Density varies with temperature and, for gases, strongly with pressure, so any density figure needs its conditions stated. Water peaks at about 999.972 kg/m3 near 4 degrees Celsius and falls to 958 kg/m3 at boiling - a four percent swing that matters for tank calibration and for any mass-from-volume calculation. Specific gravity is density divided by a reference density and is therefore dimensionless; it is only numerically equal to g/cm3 because water is so close to 1.000.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator · Editorial policy
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