For reverse:
The fundamental difference in the year count stems from the starting point: tarikh shamsi b miladi
مثال (تخمینی):
The relationship between the two is not a simple subtraction of a fixed number because the Shamsi year starts in late March, and the Gregorian year starts in January. For reverse: The fundamental difference in the year
The Shamsi year 1 corresponds to the migration of Prophet Muhammad (the Hijra) in 622 CE. Generally, you add (for the first 9 months of the Gregorian year) or tarikh shamsi b miladi