Piping
Pipe Head Loss Calculator
This calculator combines Darcy-Weisbach friction (major) head loss and user-supplied minor (K-value) head loss into a total head loss and equivalent pressure drop. The Darcy friction factor and total K-value must be supplied by the user. This is not a pipe network solver, pump selector, or full line sizing tool.
TypeInteractive calculator — separate from unit conversions
Calculator
Pressure:
Head:
Result
Major head loss (h_major)4.07886 m
Minor head loss (h_minor)0 m
Total head loss (h_total)4.07886 m
Equivalent pressure drop (ΔP)40 kPa
Formulas
Major head loss
h_major = f × (L/D) × v²/(2g)
Minor head loss
h_minor = K_total × v²/(2g)
Total head loss
h_total = h_major + h_minor
Equivalent pressure drop
ΔP = ρ × g × h_total
Diagram
Worked example
Water (ρ = 998 kg/m³) at 2.5 m/s in a 150 mm pipe, 100 m long. f = 0.020, K_total = 5.0, g = 9.80665 m/s².
- 01v²/(2g) = 2.5² / (2 × 9.80665) = 0.3187 m
- 02h_major = 0.020 × (100/0.15) × 0.3187 = 4.249 m
- 03h_minor = 5.0 × 0.3187 = 1.594 m
- 04h_total = 4.249 + 1.594 = 5.843 m
- 05ΔP = 998 × 9.80665 × 5.843 = 57,186 Pa ≈ 57.19 kPa
Result
Total head loss is 5.843 m. Equivalent pressure drop is 57,186 Pa (57.19 kPa).
FAQ
Is this full pipe network modelling?
No. This calculates losses for a single pipe run with fittings. It does not solve branching networks, parallel paths, or loop systems.
Does this calculate friction factor automatically?
No. You must supply the Darcy friction factor. Use the separate Friction Factor calculator if needed.
Does this look up K-values?
No. You must supply the total K-value by summing individual fitting K-values manually.
Does this include elevation head or pump curves?
No. This calculator computes friction and minor losses only. Elevation changes require the Bernoulli equation. Pump selection is outside scope.
Is this a pump selection tool?
No. This calculates pipe head loss only. Pump selection requires manufacturer curves, NPSH analysis, and system curve intersection, which are not implemented.