The invention relates to the technical field of cellphone radiation detection, specifically a method for calculating the radiation of a cellphone during a call. The calculation method specifically comprises the following steps: extracting the received power intensity of the cellphone; judging the type of a wireless network where the cellphone is located; calculating the transmitted power intensity of the cellphone according to the type of the wireless network; calculating the radiation intensity when the cellphone is close to a brain; and converting the radiation intensity into the safety time of radiation according to the international standard. The method enables the received power of the cellphone to be converted into the proper safety time of radiation through different formulas according to the type of the wireless network. Compared with the prior art, the method is advantageous in that the method can predict the call radiation in advance but does not monitor the radiation of the cellphone during the call, and brings convenience to a user for reasonably arranging the use time of the cellphone in advance. The method enables the radiation intensity to be converted into the safety call time according to the international standard or the national standard, and is simple and clear. The user can easily accept the concept of time, thereby facilitating the control of the use of the cellphone.