The calculator presented here can be used to calculate equivalent length for a set of piping fittings based on cumulative K factor of those fittings. This calculator is based on Darcy's Equation and Darcy friction factor for calculation of pressure drop for single phase flow.
The equivalent length calculated here can be added to the straight pipe length to obtain the total equivalent length of the whole piping system. For minor variations in flow this equivalent total length remains the same and changes in pressure drop may be obtained by directly multiplying the pressure drop per unit length by this total equivalent length.
Usually pipes are accompanied by bends, fittings, valves etc. Use EnggCyclopedia's K-factor calculator to obtain K-factor for fittings in a line.