Flange Weight Calculator
Exact weight of plate and blind flanges from geometry — with bolt-hole deduction
Flange weight follows directly from geometry: an annular disc minus the bolt holes. Weight = density × thickness × (ring area − holes area). For flat plate flanges and blind flanges this calculation is exact — no lookup table needed, and it works for any custom or non-standard flange.
Enter the outer diameter, bore (0 for a blind flange), thickness, and the bolt pattern. The calculator deducts every bolt hole and multiplies by the density of your material — carbon steel, stainless, or aluminum.
Why it matters: flanges are bought by the piece but shipped by weight, and a DN500 plate flange can weigh over 60 kg. Knowing order weight up front keeps freight quotes honest and crane planning safe. For standard weld-neck flanges (ASME B16.5, EN 1092-1 type 11), the hub adds weight this plate formula does not capture — check manufacturer data for those.
Frequently Asked Questions
How do I calculate flange weight?
For plate and blind flanges: weight = density × thickness × (π/4 × (OD² − bore²) − holes × π/4 × hole-diameter²). This calculator does that arithmetic with proper unit handling — enter dimensions in mm and get kilograms.
Does this work for weld-neck flanges?
Not exactly — weld-neck flanges have a conical hub that adds 15–30% weight over a plate flange of the same rating. Use this as a lower-bound estimate, or consult ASME B16.5 / EN 1092-1 manufacturer tables for catalog weights.
How much does a blind flange weigh?
Set the bore to 0 and the calculator gives the exact solid-disc weight minus bolt holes. Example: a 350 mm OD × 30 mm blind flange in carbon steel with 12 × 22 mm holes weighs about 21.4 kg.
Which density should I use for stainless flanges?
8,000 kg/m³ covers austenitic grades (304/316), the most common flange stainless. Duplex is slightly lower (~7,800); the difference is under 3%.