The widely accepted limiting efficiency for crystalline silicon solar cells with Lambertian light trapping under 1 sun was previously calculated to be 29.43% for a 110-μm-thick device by using the commonly applied weak absorption approximation for light trapping. However, the short-circuit current density increases by 0.17 mA/cm2 when modeling the optical absorptance of an ideal Lambertian light trapping scheme exactly. The resulting new 1-sun efficiency limit is 29.56% and holds for a cell that is 98.1 μm in thickness.