Estimating-style ductwork weight calculator for straights and fittings.
Calculates bare weight, insulation, cladding,
accessories, installed total, kg/m and kN/m.
| Item | Geometry | Area (m²) | Bare | Insul. | Clad. | Acc. | Installed | kg/m | kN/m | × |
|---|---|---|---|---|---|---|---|---|---|---|
| No items yet. Use the builder above to add duct items. | ||||||||||
| Component | Value | Notes |
|---|---|---|
| — | ||
About this ductwork weight & loading calculator
This free ductwork weight & loading calculator builds an estimating-style schedule of duct straights and fittings, then works out the developed area, bare metal weight, insulation, cladding, accessories and total installed weight per item and for the whole run. It also reports the average line load in kg/m and kN/m, so UK building-services engineers, ductwork estimators and HVAC contractors can size supports, plan lifting and price take-offs in the browser. Add straights, bends, tees, shoes, Y-pieces, risers, offsets and end caps in rectangular or circular form, pick galvanised steel, stainless steel or aluminium, and switch the output between kilograms and kilonewtons.
How the weight is calculated
Bare sheet-metal mass follows BS EN 1505 (rectangular) and BS EN 1506 (circular) duct geometry: perimeter × developed length × thickness × material density × (1 + fabrication allowance %), where the allowance covers flanges, seams, stiffeners and reinforcement. Bend developed length comes from the centreline arc π·r·(angle/180), and fitting areas for tees, shoes and Y-pieces use practical estimating multipliers (BSRIA/HVCA-style approximations) rather than full fabrication development. Insulation and cladding are quantified at the outer wrap surface, scaling the metal area by the perimeter-growth ratio in line with BS 5970 / TIMSA HVAC guidance, then multiplied by insulation thickness and density (or a kg/m² cladding figure). Installed weight is bare + insulation + cladding + accessories.
Frequently asked questions
Which standards does it use?
Bare-duct mass is based on BS EN 1505 and BS EN 1506 sheet-metal duct geometry, and insulation quantities follow BS 5970 / TIMSA HVAC guidance taken at the outer wrap surface. Fitting area factors are practical BSRIA/HVCA-style estimating approximations, not full fabrication development.
What is the kN/m output for?
It converts the average installed weight per metre of duct run (kg/m) into a line load in kN/m, giving an approximate support loading for spacing and bracket checks. It is shown only where a meaningful line length exists.
Can I rely on it for final support design?
No. The figures are for support and loading take-offs and design guidance only. Verify the final support design against the actual construction, pressure class and support spacing, and consult a qualified structural engineer for critical loads.