Hex Bolt (Full Thread) Weight Calculator
Select a fastener type below to calculate accurate approximate weights across Metric and Imperial specifications for multiple industrial metals.
Hex Bolt (Full Thread) Parameters
Configure size, length, material and optional hex nuts
Select 0 for fastener weight only, or choose 1-4 nuts to include them in the total unit weight.
Fastener Technical Sketch
Full ThreadTheoretical weight is approximated using the effective pitch cylinder diameter: d₂ = (d - 0.6495 × P), giving accurate continuous 60° V-thread volume.
Step-by-Step Bolt Weight Calculation Formula
Understanding how industrial CAD algorithms model thread crests, pitch line balance, and hexagon volumes.
1. Pitch Cylinder Shank Volume ($V_{shank}$)
Standard bolts feature 60° triangular grooves. Approximating the shank as a plain cylinder using nominal diameter ($d$) overstates weight by 10% to 14%. MetaliqForge utilizes the effective pitch diameter line ($d_2$), where metal volume of ridges equals the void volume of root grooves:
V_shank = (π / 4) × (d₂)² × Length
For an M12 × 50 mm bolt (Pitch = 1.75 mm): $d_2 = 12 - (0.649519 imes 1.75) = 10.863$ mm.
2. Hexagonal Head Volume ($V_{head}$)
The bolt head is calculated as a regular hexagonal prism across width across flats ($s$) and head thickness ($k$), adjusted with a standard 0.925 factor for the manufactured top chamfer and bottom fillet radius:
For M12 ($s = 19$ mm, $k = 7.5$ mm): $V_{head} pprox 2.17$ cm³.
• Shank Volume = (π / 4) × (1.0863 cm)² × 5.0 cm = 4.634 cm³
• Hex Head Volume = 0.8660 × (1.9 cm)² × 0.75 cm × 0.925 = 2.169 cm³
• Net Metal Volume = 4.634 + 2.169 = 6.803 cm³
• Calculated Theoretical Weight = 6.803 cm³ × 7.85 g/cm³ ≈ 53.4 grams per piece
Standard Metric Hex Bolt (Full Thread) Weight Chart
Approximate weight per 100 pieces (kg/100 pcs) for standard carbon steel and SS 304 fasteners.
| Size & Length | Pitch (mm) | Head AF (s) | Mild Steel (kg/100 pcs) | SS 304 (kg/100 pcs) | Matching Nut Weight (kg/100 pcs) |
|---|---|---|---|---|---|
| M6 × 25 mm | 1.00 | 10 mm | ~ 0.82 kg | ~ 0.84 kg | ~ 0.25 kg |
| M8 × 30 mm | 1.25 | 13 mm | ~ 1.85 kg | ~ 1.89 kg | ~ 0.52 kg |
| M10 × 40 mm | 1.50 | 17 mm | ~ 3.65 kg | ~ 3.72 kg | ~ 1.16 kg |
| M12 × 50 mm | 1.75 | 19 mm | ~ 5.34 kg | ~ 5.44 kg | ~ 1.73 kg |
| M16 × 60 mm | 2.00 | 24 mm | ~ 12.10 kg | ~ 12.33 kg | ~ 3.33 kg |
| M20 × 80 mm | 2.50 | 30 mm | ~ 24.80 kg | ~ 25.27 kg | ~ 6.44 kg |
| M24 × 100 mm | 3.00 | 36 mm | ~ 44.20 kg | ~ 45.05 kg | ~ 11.00 kg |
Weights indicate bare fastener without surface plating. Hot-dip galvanization adds approx 4% to 8% surface mass.
Frequently Asked Fastener Weight Questions
Why is theoretical fastener weight important in structural fabrication?
In heavy pre-engineered buildings, bridges, and offshore platforms, thousands of bolt-nut assemblies can contribute several metric tons to total dead loads. Accurate theoretical weight calculation enables precise shipping freight logistics, crane payload calculations, and raw material cost projections.
What is the difference between bare weight and galvanized weight?
Bare or black finish bolts reflect the true metallurgical density of the underlying alloy. Hot-dip galvanization (HDG) applies 40 to 80 microns of molten zinc onto threads and heads, which typically increases individual piece weight by 3% to 8% depending on the diameter-to-surface-area ratio.
Can I calculate weight for studs and threaded rods with custom nuts?
Yes. MetaliqForge includes dedicated configurations for continuous threaded studs and permits selecting 0, 1, 2, 3, or 4 industrial hex nuts per assembly, accurately breaking down body mass versus nut mass.
How the calculator works
The calculator converts all inputs into millimetres and determines net metal volume using analytical thread geometry before applying material density.
Weight ≈ Net Fastener Volume (cm³) × Material Density (g/cm³)
Full-thread shank volume is modeled precisely using the thread pitch line, where metal ridge volume and groove space are identical.
Legal & Trademark Notice: All international standards and designations referenced on this website (including DIN, ISO, ASME, ANSI, and ASTM) belong to their respective standard-setting organizations. MetaliqForge is an independent engineering utility platform and is not officially affiliated with or endorsed by any standard-setting authority.