When auction house data actually updates

Everyone knows the auction house API refreshes about once an hour. Almost nobody knows that EU and US do it in completely different shapes — which changes what a cross-realm comparison actually means.

The received wisdom, and what it misses

Blizzard publishes auction data per connected realm, roughly hourly. That much is documented. What the documentation does not say is whether all the realms in a region turn over together or independently — and the answer turns out to differ by region.

We watch every realm in both regions continuously, and each snapshot records the timestamp Blizzard itself stamped on that realm's data. Grouping those timestamps is enough to see the shape.

Europe arrives as a block

Over a recent two-hour window, EU produced four distinct update timestamps in total:

Eighty-nine of ninety-two realms share a single timestamp. The handful of stragglers land within the same minute. For practical purposes the entire European region turns over at once, on the half-hour-ish, and there is a genuine moment where every EU price on the site is as of the same instant.

The Americas do not

The same two hours in US produced thirty-eight distinct timestamps. A sample from one wave:

Same wave, same hour, but the realms are staggered across minutes in small clusters. There is no instant at which the whole US region is current, because by the time the last realm publishes, the first one is already a minute or two stale.

Why it matters if you compare across realms

Any cross-realm price comparison is a claim about a moment in time. In Europe that claim is clean: all the realms in the comparison were photographed together.

In the Americas the same comparison quietly mixes timestamps. Two realms a few minutes apart in the same wave can genuinely differ — someone undercut in the gap. The comparison is still useful, and it is still the best available picture, but it carries a couple of minutes of blur that the European one does not.

That is why every price on the site is shown with the timestamp of the realm it came from, rather than one figure for the whole region. When we say "updated 12 minutes ago", that is the realm's own stamp, not an average.

The best moment to look

Prices decay in a predictable direction: undercutting is continuous, so within an hour the cheapest listing tends to drift down, and a listing you saw at the top of the hour may already be gone by the middle of it.

The freshest possible view is the minute or two right after a wave lands. Whether that is worth timing your session around depends on what you are doing — for casual buying it makes little difference; for flipping at volume, the difference between a two-minute-old and a fifty-minute-old snapshot is the difference between a real undercut and a wasted deposit.

The site knows when the last wave arrived per region and shows it. If you are working seriously, watch that number rather than the clock.

How we keep up with it

Because the two regions behave differently, so do we. Realms are polled continuously rather than on a fixed schedule, and each is stored the moment its published timestamp advances. In practice that means a European wave is fully captured within about ninety seconds of Blizzard publishing it, and an American wave within about the same, spread across the staggered arrivals.

None of that is visible on the site, and it should not need to be. It is simply the reason the numbers are as current as they are.