Experiments were performed to investigate bubble splitting by turbulent fluid flow. A liquid jet was discharged vertically upwards through an orifice into a large volume of the same liquid. A shear layer was thus formed around the jet as it entered the surrounding liquid. A bubble rising through the jet splits in the shear layer. The measured size spectra can be well represented by an upper limit log-probability function with two constant parameters and only one variable, the maximum stable bubble diameter, d(bmax). Therefore, the critical Weber number including the maximum stable bubble diameter is correlated as a function of the Reynolds number based on the mean liquid velocity through an orifice.