Pipeline Sizing Calculator

Choose units, set targets, and compare options fast. See diameter, velocity, losses, and checks instantly. Download results, document assumptions, and size pipelines confidently everywhere.

Enter design inputs
Pick a sizing mode, set units, then calculate diameter and hydraulic checks.
Large: 3 columns • Small: 2 • Mobile: 1
“Both” picks the larger diameter required by either limit.
Recommended ranges are common starting points, not a code requirement.
Used for velocity constraint. Entered value is ignored when recommended mode is selected.
Used for pressure-drop sizing. Set to 0 to skip this constraint.
Use a value appropriate to your pipe material/condition.
Sum of fittings/valves losses (dimensionless).
Adds static head: ΔP = ρgΔz.
Reset

Example data table

Sample scenarios computed using this calculator’s current formulas and assumptions.
Scenario Flow (m³/h) Diameter (mm) Velocity (m/s) ΔP per 100 m (kPa) Suggested size
Cooling water loop 40.00 96.7 1.512 43.56 NPS 4 (ID≈4.026 in)
Light oil transfer 43.20 142.4 0.753 22.66 NPS 6 (ID≈6.065 in)
Compressed air header 1,800.00 266.0 9.000 0.48 NPS 12 (ID≈11.938 in)
These examples are indicative. Real projects should include detailed fittings, property tables, compressibility for gases, and specification-driven IDs.

Formula used

  • Continuity: Q = A·V, with A = πD²/4 → D = √(4Q / (πV))
  • Reynolds number: Re = ρVD / μ
  • Friction factor: laminar f = 64/Re; otherwise Swamee–Jain approximation
  • Darcy–Weisbach head loss: hf = f·(L/D)·(V²/(2g))
  • Minor losses: hm = K·(V²/(2g))
  • Static head: hs = Δz
  • Pressure drop: ΔP = ρg·(hf + hm + hs)

How to use this calculator

  1. Choose a sizing mode: velocity, allowable pressure drop, or both constraints.
  2. Enter flow rate and pick a fluid profile (or set a specific target velocity).
  3. Enter pipeline length, roughness, density, viscosity, fittings loss K, and elevation change.
  4. Press Calculate to see diameter, velocity, Reynolds number, and pressure drop above the form.
  5. Use Download CSV for records, or Download PDF for a shareable report.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.