Mass per unit length.
Mechanics · Mass and materials
Metal weight and linear mass calculator
Choose a simple shape or standard profile, or enter a known area to obtain mass per length, per piece and for the full quantity.
Created v1.0
By Thibaut Grzelak, Mechanical Analysis Engineer
Tube mass and self-weight: worked example
One piece: 25.303 kg. Self-weight per individual tube: 0.041356 kN/m. Do not add it twice to a beam load.
01Formulas and symbols
Formulas used
ρALinear massρALnTotal massmgTotal weight02Assumptions and limits
Scope of validity
- Constant section along the full length.
- Uniform material density.
- Standard profiles use recalculated simplified nominal geometry.
- Tolerances, fillets, coatings, welds and cutting losses are excluded.
- Weight uses standard gravity g = 9.80665 m/s².
03Validation example
Reference numerical case
- A = 850 mm², L = 2 m, quantity 4, stainless steel 8,000 kg/m³.
- Linear mass = 6.8 kg/m.
- Mass of one piece = 13.6 kg.
- Total mass = 54.4 kg and total weight = 533.48 N.
04Frequently asked questions
Questions about the calculation
Which input method should be used?
Choose a simple shape to calculate A from dimensions, a standard profile to reuse the library, or “Known area” when the net material area is already available.
What is the difference between mass and weight?
Mass is expressed in kilograms. Weight is the force m·g and is expressed in newtons.
Is steel density always 7,850 kg/m³?
It is a common nominal value. Alloy grade, stainless composition and product tolerances can change it.
05References
Technical references
- BIPM, The International System of Units (SI), 9th edition.
- Typical room-temperature densities; verify the exact grade and material certificate for contractual calculations.
Mass per unit length
How to calculate linear mass in kg/m
Linear mass, mass per length and profile weight per metre describe the same quantity. It depends on net material area and density.
Linear-mass formula
Convert A to m² and use ρ in kg/m³. The result is obtained in kg/m.
m′ = ρ · AVerified steel example
A = 2,500 mm² and ρ = 7,850 kg/m³ give m′ = 19.625 kg/m. A 6 m member has a mass of 117.75 kg.
7 850 × 0,0025 = 19,625 kg/mUse net material area
For a tube or open section, do not use the outer bounding rectangle. Obtain area from the appropriate calculator.