How the total is computed
Each period is measured as calendar-accurate years, months, and days (so 15 Jan to 15 Feb is exactly one month, whatever the month length). The periods are then added together, carrying 30 days into a month and 12 months into a year, which is the convention most HR forms and visa applications expect.
Overlapping jobs
If two periods overlap, for example a part-time role alongside a full-time one, the headline total counts both. The overlap-adjusted line below it counts each calendar day only once, which is what most employers mean by "total years of experience."
Hijri dates for Gulf contracts
Saudi iqamas and many GCC contracts state dates in the Hijri calendar. Switch to Hijri to enter them directly; the tool uses the tabular (civil) calendar, so official moon-sighting dates can differ by a day.