1. Set your design flow
Enter the liquid flow at operating conditions and the maximum average velocity allowed by your design.
2. Review the size
Enter your inputs, then select Size pipe.
Next, verify pressure drop and wall thickness for your design conditions.
3. Compare standard sizes
Every row uses your design flow. “Meets limit” checks velocity only.
| NPS | DN | Inside diameter (mm / in) | Velocity (m/s / ft/s) | Velocity check |
|---|
How pipe sizing works
Dmin = √(4Q / (πvmax))
v = 4Q / (πDinside²)
The required diameter comes from continuity for a full circular pipe. The calculator selects the smallest listed nominal size whose inside diameter meets the velocity limit, using unrounded values. Dimensions are nominal; verify the purchased pipe’s actual bore, lining, and tolerances.
This is preliminary velocity-based sizing for single-phase liquids. It does not check pressure loss, pump capacity, surge, erosion, solids transport, minimum self-cleaning velocity, or pressure rating. Gas, steam, partially full drains, and two-phase flow require other sizing methods. A schedule selection here specifies dimensions, not a pressure rating.
Pipe dimensions: Wheatland ASTM A53 Schedule 40 and 80 dimensional tables. Calculations use the published inch IDs converted with exactly 25.4 mm/in.