Someone in Los Angeles asks when you're free next week. You check three calendars, type out a list of times, convert each one to Pacific in your head, and hope you didn't miss a meeting. Then they reply with a time that's already gone.
Start with the overlap
Before offering times, know which hours both of you are working. New York and Los Angeles share 12 to 5 PM Eastern. New York and London share only the morning in New York. Los Angeles and London don't overlap in a normal 9-to-5 at all. The time zone overlap calculator works it out for any set of cities.
Option 1: send your open times in both zones
Write each window in your zone and theirs, so nobody has to convert:
Tue, Nov 3: 9–11:30 AM EST · 6–8:30 AM PST
Wed, Nov 4: 1–4 PM EST · 10 AM–1 PM PST
TimeIQ builds this list for you from every connected calendar: pick the days, add a second (or third) time zone, and copy it as text or as a picture of your week. It ends with your booking link.
Option 2: send a booking link
A booking link shows open times in the visitor's own time zone automatically, and the time they pick is confirmed against your calendars before it's booked. Send the list when you want to offer a few specific slots, and the link when you're happy for them to choose.
Daylight saving catches everyone
The US and Europe change clocks on different weekends in March and in October and November, so for a few weeks the usual gap is off by an hour. Tools that compute times from real time zone data handle it; mental math usually doesn't.