Guide

Time Zones Explained

A plain-English guide to time zones, UTC offsets, and why local times change around the world.

A time zone is a regional rule for converting UTC into local civil time. Most tools show an offset such as UTC+1 or UTC-5, but the real rule is more than a fixed number because many regions change clocks seasonally.

For everyday planning, the safest way to compare cities is to use an IANA time zone name such as America/New_York or Europe/London. These names include historical and daylight saving rules where the browser supports them.

When scheduling meetings, always compare the target date, not just the cities. A difference that is five hours in winter may become four hours in summer if one place changes clocks earlier than another.