For insulation, lagging and cladding takeoff. Mix pipe, rectangular duct and round duct in one list, add insulation thickness, and get bare and insulated surface area straight away — in m² or ft².
| Type | Size | Length | Qty | Insul. thk | Surface area |
|---|
Nothing exotic here — but two details trip people up often enough to be worth spelling out.
Bare area = π × OD × length
Insulated area = π × (OD + 2 × thickness) × length
Insulation wraps the pipe, so its outer surface is one thickness further out on every side — which is why the diameter grows by two thicknesses, not one.
Bare area = 2 × (width + height) × length
Insulated area = 2 × ((W + 2t) + (H + 2t)) × length
That first part is just the perimeter of the duct cross-section. Multiply by the run length and you have the wrapped area.
The single most common error in pipe insulation takeoff. A 50NB pipe does not have a 50 mm outside diameter — it is 60.3 mm. Using the nominal figure under-measures the area by roughly 17% on that size, and the error is worse on smaller bores: 15NB is 21.3 mm against a nominal 15, which is 42% low.
The size dropdown above fills in the correct ASME B36.10 outside diameter for each nominal bore. You can also type a custom OD if you are working to a different standard.
This calculator gives you the straight-run figure. Elbows, tees, valves and flanges take disproportionately more insulation material and a lot more labour than the equivalent length of straight pipe, so most estimators add a percentage allowance on top. What that percentage should be depends on your specification and how fitting-dense the system is — apply your own.
For bare pipe, surface area = π × outside diameter × length. For insulated pipe you are measuring the outer surface of the insulation, so the diameter becomes the pipe OD plus twice the insulation thickness: π × (OD + 2t) × length.
Insulation and cladding are normally billed on this outer area, which is why the insulated figure is always larger than the bare pipe figure.
Surface area = 2 × (width + height) × length — the perimeter of the cross-section multiplied by the run length. For insulated duct, add twice the insulation thickness to both width and height first.
Outside diameter, always — that is the surface being insulated. Picking a nominal bore fills in the corresponding standard OD from ASME B36.10. For example 50NB (2") is 60.3 mm, not 50 mm. You can enter a custom OD instead if you need to.
Free, no signup, no limits. It runs entirely in your browser — nothing you type is sent to a server or stored anywhere. Closing the tab clears it.
Usually yes. Insulating elbows, tees, valves and flanges costs far more per metre than straight pipe. This calculator gives you the straight-run area so you can apply the allowance your specification calls for on top.
Yes — that is what TitanBQ Pro does. You trace the runs on the PDF drawing itself and it tracks length and surface area together as you go, then exports the lot to Excel. This calculator is the manual version for when you already have your lengths.
If you are keying lengths into a calculator, you have already done the slow part by hand. TitanBQ traces the run on your PDF and tracks length and surface area together — then exports the whole BOQ to Excel.