Inside Apple's iPhone Store Availability

Those of you still following Apple's Retail guide to iPhone availability may want to know how the retail store algorithm works.

At 9 p.m. every night (local time), the inventory is checked at each Apple Store. Those with less than 10 8GB iPhones are considered to be "out of stock" for the following morning. Therefore, the tool tells us nothing about the status of 4GB iPhones at the Apple Stores.

Beyond this, Apple Stores appear to be getting daily shipments (except Sunday) of new Apple iPhones, so even if your store is listed "out of stock", new iPhones are likely arriving at some point during the following day.