Datedif Formula In Excel calculates the differnce between 2 date in 6 variations. In the Datedif Formula In Excel the following are used "d" Days between the two dates. "m" Months between the two dates. "y" Years between the two dates. "yd" Days between the dates, as if the dates were in the same year. "ym" Months between the dates, as if the dates were in the same year. "md" Days between the two dates, as if the dates were in the same month and year.