Colebrook-White Equation

Colebrook-White equation, also called Colebrook equation, is used toiteratively solve the Darcy-Weisback friction factor. This equation uses US units. To convert between US and SI units, use our calculator.

 

Colebrook-White Equation formula
\(\large{ \frac{1}{\sqrt{f}} = -2 \; log_{10} \left( \frac{ \epsilon\ }{ 3.7 \; d_h } + \frac{ 2.51 }{ Re \; \sqrt{ f } } \right) }\)
Symbol	English	Metric
\(\large{ \epsilon }\) (Greek symbol epsilon) = absolute roughness	\(\large{ in }\)	\(\large{ mm }\)
\(\large{ f }\) = friction factor	\(\large{ dimensionless }\)
\(\large{ d_h }\) = hydraulic diameter	\(\large{ in }\)	\(\large{ mm }\)
\(\large{ Re }\) = Reynolds number	\(\large{ dimensionless }\)