Choosing Storage Classes Without Triggering the Minimum-Duration Trap

Storage class selection is roughly a 23x cost range for the same bytes (S3 Standard at ~$0.023/GB down to Glacier Deep Archive at ~$0.00099/GB) — but the cheaper classes trade that discount for real constraints: minimum storage durations, minimum billable object sizes, and retrieval fees that don't exist on Standard.

Glacier Flexible Retrieval and Glacier Instant Retrieval both carry a 90-day minimum storage duration; Glacier Deep Archive carries 180 days. Delete or transition an object before that window closes and S3 charges a prorated early-deletion fee — you pay for the remaining days as if the object were still there. A lifecycle policy that transitions short-lived objects (log files cleaned up after 60 days, say) straight to Glacier at day 30 can end up costing more than leaving them on Standard-IA, because the early-deletion fee plus Glacier's per-object metadata overhead eats the discount — and that overhead isn't uniform across Glacier classes, which is an easy mistake to make. Glacier Flexible Retrieval and Deep Archive each add 40 KB of metadata overhead per object, split: 8 KB billed at Standard rates, 32 KB billed at the respective Glacier class's own rate. Glacier Instant Retrieval doesn't carry this overhead at all — it relies solely on its 128 KB minimum billable object size instead (see Decision Drivers below). Conflating the two mechanics — treating Instant Retrieval as if it also had the 40 KB metadata charge — overstates its cost for small objects.