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Does "ETA" stand for "Estimated Time to Arrival" or "Estimated Time of Arrival"? I most commonly hear phrases like "ETA 20 minutes", but I've also heard "ETA 4:30 PM". Is one usage correct and the other wrong, or are both okay?

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closed as general reference by MετάEd, Mehper C. Palavuzlar, tchrist, Matt E. Эллен, Kate Gregory Feb 22 '13 at 12:52

This question is too basic; it can be definitively and permanently answered by a single link to a standard internet reference source designed specifically to find that type of information.If this question can be reworded to fit the rules in the help center, please edit the question.

Of - that part is general reference. – J.R. Feb 22 '13 at 5:22
In general, it is much more likely that a term denoting a constant will have a special name than a term denoting a constantly-changing variable, which is what estimated time to arrival would be. If it were even as good as MicroSoft Windows at estimating times, it would not be a useful thing to know. – John Lawler Feb 22 '13 at 5:26
@JohnLawler off-topic nitpick: the word Microsoft has never been CamelCased, ever. – Mr Lister Feb 22 '13 at 13:21
up vote 3 down vote accepted

ETA appears to be defined as the estimated time of arrival.

It's fine to use either format. ETA is used to answer the question, "When is X expected to arrive?", which can be answered either as, "In 20 minutes" or "At 4:30 PM". In other words, either usage is correct.

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It's of, but that doesn't matter, because that allows both uses.

The estimated time of arrival is 10:37.

Fine, it's estimated that the person, item, etc. will arrive at 10:37.

The estimated time of arrival is 20minutes.

Fine, there's an implied context of the current time, so it's the same as "The estimated time of arrival is 20minutes from now."

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