ABSTRACT This paper shows a mathematical model assessment for fatigue crack propagation in a T-butt weld joint same thickness sheet. The assessment reached a closed-form solution for the dimensionless stress intensity factor expression, depending on crack size, for three types of weld chord profiles: straight, convex, and concave. It is established that crack growth rate for concave chord profile is lower than for the other two chord profiles. Finally, fatigue test in non-standard specimens were carried out to validate theoretical models. Fatigue life for all three weld chord profiles are within the experimental confidence interval [13280-21650] cycles for 95% probability.