AEST to EST

Enter a time in Australian Eastern Time and read it in US Eastern Time. EST is usually 14 hours behind of AEST.

Whether the gap holds all year

The gap is not the same all year: it ranges from 16 hours behind to 14 hours behind, because Australian Eastern Time and US Eastern Time change their clocks on different dates. Those few weeks are when most calls are missed by an hour.

Which zones these letters mean

AEST resolves to Australian Eastern Time and EST to US Eastern Time. Neither is ambiguous, so a time converted here means one thing only.

Questions

What does CST actually mean?

It depends who wrote it, and that is the problem. CST is US Central Time and it is also China Standard Time — fourteen hours apart. IST is India, Ireland and Israel. Every conversion page here names the zone it resolved an abbreviation to, rather than quietly picking one.

Why does the difference between two time zones change during the year?

Because countries change their clocks on different dates. The United States moves in March and November, the European Union in the last weekends of March and October, and the southern hemisphere moves the opposite way entirely. For a few weeks each year the usual gap is an hour out, which is when most mis-scheduled calls happen.