A blade for a rotor of a wind turbine having a substantially horizontal rotor shaft, said rotor comprising a hub, from which the blade extends substantially in a radial direction when mounted to the hub, the blade having a longitudinal direction (r) with a tip end and a root end and a transverse direction, the blade further comprising: - a profiled contour including a pressure side and a suction side, as well as a leading edge and a trailing edge with a chord having a chord length (c) extending there between, the profiled contour, when being impacted by an incident airflow, generating a lift, wherein the profiled contour is divided into: - a root region having a substantially circular or elliptical profile closest to the hub, - an airfoil region having a lift-generating profile furthest away from the hub, and - a transition region between the root region and the airfoil region, the transition region having a profile gradually changing in the radial direction from the circular or elliptical profile of the root region to the lift-generating profile of the airfoil region, and with - a shoulder having a shoulder width and located at the boundary between the transition region and the airfoil region, wherein - the blade has a blade length, and - the profiled contour comprises a local relative thickness defined as the local ratio between a maximum profile thickness (t) and the chord length (c), wherein - the ratio between the shoulder width and the blade length being less than or equal to 0.075, and wherein the trailing edge has a smooth shape without discontinuities in the longitudinal direction of the blade, and being characterized in that - the relative thickness (t/c) in a blade length interval of 0-0.8L is at least 22%, and wherein the trailing edge in the transition region has a curvature with an outer radius ( r o) external to the trailing edge, which at all positions is at least 0.2L, and the trailing edge in the transition region has a curvature with an inner radius ( r i) internal to the trailing edge, which at all positions is at least 0.2L. - a profiled contour including a pressure side and a suction side, as well as a leading edge and a trailing edge with a chord having a chord length (c) extending there between, the profiled contour, when being impacted by an incident airflow, generating a lift, wherein the profiled contour is divided into: - a root region having a substantially circular or elliptical profile closest to the hub, - an airfoil region having a lift-generating profile furthest away from the hub, and - a transition region between the root region and the airfoil region, the transition region having a profile gradually changing in the radial direction from the circular or elliptical profile of the root region to the lift-generating profile of the airfoil region, and with - a shoulder having a shoulder width and located at the boundary between the transition region and the airfoil region, wherein - the blade has a blade length, and - the profiled contour comprises a local relative thickness defined as the local ratio between a maximum profile thickness (t) and the chord length (c), wherein - the ratio between the shoulder width and the blade length being less than or equal to 0.075, and - the relative thickness (t/c) in a blade length interval of 0-0.8L is at least 22%, and wherein the trailing edge in the transition region has a curvature with an outer radius ( r o) external to the trailing edge, which at all positions is at least 0.2L, and the trailing edge in the transition region has a curvature with an inner radius ( r i) internal to the trailing edge, which at all positions is at least 0.2L.