Array size scaling of passive coherent beam combination is explored theoretically. The Strehl ratio variation with wavelength is simulated in 4-, 9-, 16-, and 25-channel fiber arrays. The average Strehl ratio and phase error are calculated. The Strehl ratio is found to be near 100% for arrays with less than 5 fibers, but decreases significantly for larger arrays. These results are in good agreement with the recent experimental results. The size scale scaling of passive coherent beam combination is explored theoretically. The Strehl ratio variation with wavelength is simulated in 4-, 9-, 16-, and 25-channel fiber arrays. The Strehl ratio is found to be near 100% for arrays with less than 5 fibers, but decreased significantly for larger arrays. These results are in good agreement with the recent experimental results.