Density of carbon steel and mild steel

The density of a material is the mass in a given volume and is a vital consideration while procuring materials for industrial applications. The density of carbon steel is lower than stainless steel at 7,850 kg/m3. Mild steel is around the same ballpark, at 7,860 kg/m3. Tool steel, in steep demand for manufacturing tools with a cutting edge, has more than 0.6% carbon. Its density ranges from 7,720 to 8,000 kg/m3.

The differentiator between carbon and mild steel is the percentage of carbon. While the former has more (0.05 to 2.1%) and is robust but less ductile, mild steel has less carbon (0.05 to 0.25%). Medium carbon steel has 0.30 to 0.60% carbon.

Understand relationship between density and carbon steel properties

Density plays a vital role in determining the properties of carbon steel. It affects electrical conductivity, strength, and thermal characteristics.

It gets stronger as the mass per unit volume, i.e., the density of plain carbon steel, increases. The thermal expansion rate rises since more molecules can expand in response to the elevated temperature. Likewise, the heat capacity increases as the additional molecules absorb more heat before a phase transition.

However, the electrical conductivity reduces with increasing density (because of the raised resistivity).

Is there any formula to measure the density of carbon steel lb/in3?

No particular process calculates steel density lb/in3. However, the usual formula works; just multiply the density in g/cm3 by a conversion factor of 0.036127.
Density in lb/in3 = (Mass/Volume) x 0.036127
The density of steel lb/in3 is 0.284 lb/in3 or 7.8 g/cm3.

8 reasons which can affect carbon steel properties

As carbon rises, the material becomes strong and less ductile. The properties of carbon steel and mild steel (or low carbon steel) depend upon –

  • Grain structure
  • Manufacturing technique
  • Raw materials quality
  • Elements like silicon and sulfur
  • Heat treatment carbon steel has undergone, for example, annealing (more ductile) and quenching (higher strength)
  • Rate of cooling during solidification
  • Temperature
  • Pressure (expansion or compression)

Convert g/cm3 to kg/mm3

Standard units for mass and volume are kilogram and m3. However, if the laboratory measurements use grams and cm3, users can just change the units into carbon steel density kg m3 by multiplying by 1000.
1 kg/mm3 = 0.000001 g/cm³.

Convert lbs/in3 to kg/m3

The US uses Imperial units (lb/pounds) to measure density. Users can directly convert lbs per cubic inches to kg/m3:
1 lb/in³ = 27679.9 kg/m³

The formula to calculate density

The straightforward formula to calculate the density of mild steel in g cm3 is dividing the object’s mass by volume. Both metric and imperial units are permissible.
Density = Mass/Volume

Why does density increase or decrease?

The density of steel will rise if the mass increases. But it lowers with volume. Numerous other factors impact density, like temperature, pressure, the material state, and salinity.

Does the density of steel depend upon temperature?

Temperature can affect the density of steel, changing its properties based on its composition and previous heat treatments.

As the temperature increases, the molecules in steel assume faster speeds and start spreading apart. They take up a larger volume, decreasing the steel density. So, hard steel softens after exposure to elevated temperatures.
Similarly, the molecules come closer when the steel cools, upping the density.

Are there any testing methods to verify density?

Density gets tested using the buoyancy technique based on the Archimedes principle. It states that the loss in weight upon immersing the material in water equals the fluid displaced. Hydrometers (glass/digital) measure the density of carbon steel lb in3 via this technique.

A more contemporary approach is helium pycnometry. The sample material gets sealed and maintained at a specific temperature. Then, helium gets added, seeping into minute pores. The difference between the weights (with and without the sample) divided by the compartment volume gives the density.

Steel density comparison chart:

Density of steel The steel density lb/in3 can be presented below.

Steel Name Density (g/cm3) Density (lb/in3)
AISI 1020 7.87 g/cm3 0.284 lb/in3
AISI 1045 7.85 g/cm3 0.283 lb/in3
AISI 1018 7.87 g/cm3 0.284 lb/in3
ASTM A36 7.85 g/cm3 0.283 lb/in3
C45 7.85 g/cm3 0.283 lb/in3
S45C 7.85 g/cm3 0.283 lb/in3
AISI 1045 7.85 g/cm3 0.283 lb/in3
AISI 1010 7.87 g/cm3 0.284 lb/in3
  • Density of carbon steel lb in3 (plain): 7.75 to 8.05 g/cm3 or 0.280 to 0.291 lb/in3
  • Low Carbon Steel (Mild Steel): 7.85 g/cm3 or 0.284 lb/in3
  • Density of mild steel in g cm3: 7.75 to 8.05 g/cm3 or 0.280 to 0.291 lb/in3
  • High Carbon Steel: 7.75 to 8.05 g/cm3 or 0.280 to 0.291 lb/in3


Metals are known for their resilience and density, primarily attributed to metallic bonding and electrostatic attraction. However, a higher density does not mean greater strength. Materials with a high strength-to-weight ratio are in great demand in engineering and construction to save costs.

High carbon steel and mild steel build machinery parts, industrial castings, construction, and automobiles. Assessing the density of carbon steel impacts the volume you will acquire at a price.

Written by: Geetanjali