Time Zone Math Is Harder Than You Think: A PST to EST Survival Guide

PST to EST is a 3-hour difference. EST = PST + 3. That's the simple version. The complicated version involves daylight saving time, and it has burned more people than any other seemingly simple calculation in distributed work. The daylight saving trap PST (Pacific Standard Time) is UTC-8. EST (Eastern Standard Time) is UTC-5. The difference is always 3 hours. But here's the catch: both regions observe daylight saving time, and they switch on the same dates (second Sunday of March, first Sunday of November in the US). During daylight saving time, the Pacific zone uses PDT (UTC-7) and the Eastern zone uses EDT (UTC-4). The difference is still 3 hours. So within the continental US, the conversion is always +3 from Pacific to Eastern, regardless of DST. The problem arises when you're converting between a US time zone and a location that doesn't observe DST (like Arizona, which stays on MST year-round) or observes it on different dates (like most of Europe, which switches on the last Sunday