Metal Bar Weight Calculator
Calculate the weight of metal bars (round, square, or flat) by entering the bar dimensions and selecting the material. The calculator uses the standard formula Weight = Volume x Density, where density values are sourced from ASTM material standards and ASM International handbooks. Results are in kilograms; multiply by 2.20462 to convert to pounds.
Metal bar weight formulas
Round bar: Weight (kg) = (pi / 4) x (D/1000)^2 x (L/1000) x rho
Square bar: Weight (kg) = (S/1000)^2 x (L/1000) x rho
Flat bar: Weight (kg) = (W/1000) x (T/1000) x (L/1000) x rho
Where D = diameter (mm), S = side length (mm), W = width (mm), T = thickness (mm), L = length (mm), and rho = material density (kg/m^3).
Material density reference table
- Carbon steel: 7,850 kg/m^3 (ASTM A36, A108)
- Stainless steel 304: 7,900 kg/m^3 (ASTM A276)
- Aluminum 6061: 2,700 kg/m^3 (ASTM B221)
- Copper: 8,960 kg/m^3 (ASTM B152)
- Brass: 8,500 kg/m^3 (ASTM B16)
- Cast iron: 7,200 kg/m^3 (ASTM A48)
Metal bar weight: frequently asked questions
How is the weight of a metal bar calculated?
Weight = Volume x Density. Volume depends on the bar cross-section: for round bars, Volume = pi/4 x diameter^2 x length; for square bars, Volume = side^2 x length; for flat bars, Volume = width x thickness x length. Density is the material-specific value in kg/m^3.
What is the density of common metals?
Steel (carbon): 7,850 kg/m^3. Aluminum (6061): 2,700 kg/m^3. Copper: 8,960 kg/m^3. Brass: 8,500 kg/m^3. Stainless steel 304: 7,900 kg/m^3. These values are per ASTM and ASM International material databases.
Can I calculate in imperial units?
This calculator uses metric (mm and kg). To convert: 1 inch = 25.4 mm; 1 kg = 2.20462 lb. Multiply the kg result by 2.20462 to obtain pounds.
Does bar profile (round vs square) significantly affect weight?
Yes. A round bar and a square bar of the same nominal dimension have different cross-sectional areas. A 50 mm round bar has area = pi/4 x 50^2 = 1,963 mm^2; a 50 mm square bar has area = 50^2 = 2,500 mm^2 -- about 27% heavier per unit length.
Why is accurate bar weight important in manufacturing?
Bar weight directly determines raw material cost, freight cost, machine load capacity, and structural compliance. An accurate weight estimate prevents under-ordering, excess freight charges, and overloading of machining equipment or structural members.
Official sources
- ASTM International: ASTM Material Standards.
- ASM International: ASM International Handbook of Materials.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.