According to observation, the number of flares on different stars almost does not change from dwarf to hot stars. As it is known from the Sun observations, the flares may be followed by the coronal mass ejection events (CME). The estimates of a magnetic field strength in tubes in photospheres of O-M stars were made. We use simple formulas with a clear physical meaning, which give results for the Sun that differ by no more than a factor of 2–3 from the observed ones. The main motivation for such approach is as follows: our knowledge of the stars’ medium is at approximately the same level as our knowledge of the Sun in the 1950s. Moreover, such simple models allow a complete picture of the processes in the system to be obtained without knowing any details of the stellar activity. Basing on the obtained values and parameters of different objects we made estimates of flare energies and estimates of CME’s masses and made some assumptions on the minimum and maximum limits for different types of stars and compare them with flares energies, stars luminosities and temperatures.