This paper presents further investigations into the axisymmetric progressive crushing behaviour of metal tubes subject to quasi-static axial loads. Based on experiments and a finite element analysis, a new, more realistic theoretical model is developed by introducing the concept of effective plastic hinge length which is proportional to tube thickness. The theoretical crushing force history, mean crushing force and plastic half-wavelength are compared with experiments and finite element analysis results. It is found that for normalized mean crushing force, P m / M o , better agreement is obtained using the present theoretical model than previous ones. This analysis helps explain the paradox between the D/t exponent calculated from experimental results and previous theoretical predictions. Also, a good estimate of plastic half-wavelength, h , is also obtained.