Worked comparisons

Real pairs, clear reasoning

See how whole-hour, half-hour, calendar-day, and seasonal differences appear in ordinary planning.

Seasonal difference5 min example

Belgrade and Moscow: a difference that changes

Belgrade changes clocks seasonally while Moscow stays on UTC+3, so the familiar difference depends on the selected date.

Half-hour offset5 min example

Asia/Kolkata uses a half-hour offset, while New York changes seasonally, so a whole-hour mental shortcut fails for this pair.