Effective heat summation requirements (EHS) of 34 grape cultivars for budburst–maturity period were determined by different methods in Antalya ecological conditions. The variations in EHS requirements of some cultivars were investigated by using four daily average temperature (DAT) calculation models by using hourly, minimum, maximum and meteorological observation temperature records. EHS requests of some varieties were compared with the values obtained in different ecologies. Among the grape cultivars, the lowest EHS request was determined in the Early Sweet cultivar. EHS requirements of this cultivar determined according to Winkler index ranged from 912 to 954 degree days (dd) for different daily average temperature calculation models. Meanwhile, The EHS requirement of Early Sweet ranged from 925 dd to 983 dd depending on calculation methods. Different DAT and EHS calculation models have led to differences in the EHS requirements of the varieties at different levels. As a result, it was determined that the correlation between the methods in calculating DAT values was very close, and it would be more convenient to take the 24-hour average in the calculations, but the use of other methods did not lead to an important error when DAT could not be provided. Furthermore, it was decided that it would be more appropriate using hourly DAT data in Winkler index for determining of EHS requirements of grape cultivars.