Steel Weight Calculator
The weight of a round steel bar follows a simple relationship with diameter and length — useful for estimating material costs or checking a delivery against what was ordered.
Inputs
Result
189.3 kg
1.578 kg per metre
How the steel weight calculator works
Weight per metre (kg/m) = diameter² ÷ 162.28, a standard approximation for mild steel's density applied to a round cross-section.
Total weight = weight per metre × length × quantity.
Worked example: 16 mm diameter, 12 m length, 10 bars
- Weight per metre = 16² ÷ 162.28 = 256 ÷ 162.28 ≈ 1.578 kg/m.
- Total = 1.578 × 12 × 10 ≈ 189.31 kg.
Common mistakes to avoid
Assuming weight scales linearly with diameter
Weight per metre depends on diameter squared, since it's proportional to cross-sectional area — doubling the bar diameter roughly quadruples its weight per metre, not doubles it.
Applying this constant to non-steel or non-round bar stock
162.28 is specific to mild steel's density for a round cross-section — square or rectangular bar, or a different metal like aluminium, needs a different constant and shape formula entirely.
Frequently asked questions
Why does the formula use 162.28 specifically?
It's derived from mild steel's density (about 7,850 kg/m³) applied to the area of a circle, simplified into a single constant so weight per metre can be found directly from diameter squared.
How would this differ for stainless steel?
Stainless steel has a slightly different density than mild steel, so the constant would shift somewhat — this calculator's constant is specifically calibrated for standard mild steel.
Does bar length affect the weight-per-metre figure?
No — weight per metre depends only on diameter (cross-sectional area); length is a separate multiplier applied afterward to get total weight.
How is this useful beyond costing a straightforward order?
It's also used to check a delivered bundle's actual weight against its expected count and length as a quality/quantity verification step.
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