Compare real named time zones
Use IANA zone names such as America/New_York or Asia/Kolkata rather than fixed UTC offsets. Named zones allow the browser to apply daylight-saving rules in its installed time-zone database.
Anchor the meeting to one location
Choose a date, time and source zone first, then compare the corresponding local times for every participant. This avoids manually adding offsets that may be wrong around daylight-saving transitions.
Watch for browser database age
Time-zone legislation can change. The conversion depends on the browser/operating system time-zone database, so confirm unusual or high-stakes scheduling against a current authoritative source.
Use working-hours indicators as preferences
A highlighted local time is only a convenience. It does not know a participant's actual work schedule, holidays, availability or cultural preferences.