Calculators

Converters

Calculator Use

Convert among mass density values along with mass concentration values (mass divided by volume).

Ounces and pounds are in the avoirdupois system, the standard everyday system in the United States where 1 ounce = 1/16 pound

How to Convert Units of Density

Conversions are performed by using a conversion factor. By knowing the conversion factor, converting between units can become a simple multiplication problem:

S * C = E

Where S is our starting value, C is our conversion factor, and E is our end converted result.

To simply convert from any unit into kg/m³, for example, from 50 lb/ft³, just multiply by the value in the right column in the table below.

50 lb/ft³ * 16.018463 [ (kg/m³) / (lb/ft³) ] = 800.92315 kg/m³

To convert from kg/m³ into units in the left column divide by the value in the right column or, multiply by the reciprocal, 1/x.

800.92315 kg/m³ / 16.018463 [ (kg/m³) / (lb/ft³) ] = 50 lb/ft³

To convert among any units in the left column, say from A to B, you can multiply by the factor for A to convert A into kg/m³ then divide by the factor for B to convert out of kg/m³. Or, you can find the single factor you need by dividing the A factor by the B factor.

For example, to convert from lb/ft³ to g/mL you would multiply by 16.018463 then divide by 1000. Or, multiply by 16.018463/1000 = 0.016018463. So, to convert directly from lb/ft³ to g/mL you multiply by 0.016018463.

To understand how to also convert the units follow this example. Say you want to convert from lb/ft³ to lb/in³. You want to convert the foot to inches.  Since you can multiply anything by 1 and still retain the original value, but in different units, set it up so that ft³ will cancel out leaving you with in³.

Since:
1 ft = 12 in, 1 ft / 12 in = 1

We can write the conversion as:
1 lb/ft³ = 1 lb/ft³ * (1 ft / 12 in)³ = 1 lb/ft³ * (1 ft³ / 1728 in³) = 5.787037e-04 lb/in³

And we now have our factor for conversion from lb/ft³ to lb/in³ since 1 * 5.787037e-04 = 5.787037e-04.

Knowing that 1 lb/ft³ = 5.787037e-04 lb/in³ we can now find the conversion factor for converting back. Dividing both sides of the equation by 5.787037e-04 we get 1728 lb/ft³ = 1 lb/in³. So, the conversion factor to multiply by to convert from lb/in³ to lb/ft³ is 1728.

References

The National Institute of Standards and Technology (NIST). The NIST Guide for the use of the International System of Units - Appendix B, subsections B.8 Factors for Units Listed Alphabetically and B.9 Factors for Units Listed by Kind of Quantity or Field of Science.

Lide, David R., Daniel (Editor-in-Chief). CRC Handbook of Chemistry and Physics, 89th Edition New York, NY: CRC Press, p. 1-28, 2008.

Wikipedia contributors. "Conversion of units" Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, last visited 26 Jun. 2011.