Minor Losses Calculator

Head loss due to fittings, bends, valves, and other pipe components using the K-coefficient method.

Fluid Mechanics II

Inputs

Flow velocity V (m/s)

Loss coefficient K (dimensionless)

For multiple fittings in series, enter the sum of all K values.

Theory

Minor loss equation:

hL = K × V²/(2g) [m]

Multiple fittings in series:

hL,total = (K₁ + K₂ + … + Kn) × V²/(2g)

Where:

hL = minor head loss [m]
K = loss coefficient (depends on fitting geometry)
V = mean flow velocity at the fitting [m/s]
g = gravitational acceleration = 9.81 m/s²

Common loss coefficients K:

Fitting	K
Sharp pipe entrance	0.5
Reentrant (projecting) entrance	0.8
Exit — any fitting	1
90° standard elbow	0.9
90° long-radius elbow	0.4
45° elbow	0.4
Gate valve — fully open	0.2
Gate valve — half open	5.6
Globe valve — fully open	10
Ball valve — fully open	0.05
Check valve (swing type)	2
Butterfly valve — fully open	0.6
Standard tee — branch flow	1.8
Standard tee — line flow	0.9
180° return bend	2.2
Sudden contraction (approx.)	0.5
Sudden expansion (approx.)	1

Minor losses are often small compared to major (friction) losses in long pipes, but dominate in short pipe systems with many fittings. Always check whether major or minor losses govern before simplifying.