# Gen1 vs Gen2 storage and IOPS billing > Source-anchored research for Gen1 vs Gen2 storage and IOPS billing. Run status: COMPLETED. Parent: [Atlas Cluster Topology and Tier Economics](https://llms-explorer.com/tree/atlas-cluster-topology-and-tier-economics/) · 4 facets · 12 facts · page: https://llms-explorer.com/tree/gen1-vs-gen2-storage-and-iops-billing/ ## Measurements and reference values - Atlas documents the Gen2 baseline as 3,000 IOPS through 1,000 GB and 3 IOPS per GB above that size: 2,000 GB includes 6,000 IOPS and 4,000 GB includes 12,000 IOPS. (low confidence) (verified as of 2026-10-18) — [source](https://www.mongodb.com/docs/atlas/customize-storage/) - Do not substitute the cloud provider's fixed 3,000-IOPS baseline for Atlas's size-dependent included baseline when estimating Gen2 costs. For example, Atlas includes 6,000 IOPS at 2,000 GB, whereas the cited provider products include 3,000 IOPS. (medium confidence) (verified as of 2026-10-18) — [source](https://www.mongodb.com/docs/atlas/customize-storage/) ## Problems, failure modes and limitations - Switching back to Gen1 can reduce IOPS when the retained Gen2 rate exceeds the Gen1 limit. Validate workload performance before treating the generation change as a cost-saving action. (low confidence) (verified as of 2026-10-14) — [source](https://www.mongodb.com/docs/atlas/cluster-config/change-cluster-generation.md) ## Comparisons and alternatives - Gen2 storage charges include the baseline minimum IOPS for the disk size. Atlas separately charges for provisioned Extended Standard IOPS above that baseline; this is provisioned capacity, rather than a count of completed operations. (high confidence) (verified as of 2026-10-20) — [source](https://www.mongodb.com/docs/atlas/billing/cluster-configuration-costs/) - Atlas states that default storage is included in the cluster hourly price, but customized storage is charged for its full capacity without subtracting the default allocation. The documented 10-to-50 GB example bills 50 GB of storage, rather than 40 GB. (high confidence) (verified as of 2026-10-20) — [source](https://www.mongodb.com/docs/atlas/billing/cluster-configuration-costs/) ## Facts and statements - For Atlas Core, Gen1 standard IOPS and storage scale together. Gen2 permits independent scaling and billing of storage capacity and additional standard IOPS. (high confidence) (verified as of 2026-10-20) — [source](https://www.mongodb.com/docs/atlas/manage-clusters/) - A Gen1-to-Gen2 switch preserves storage capacity and IOPS, plus the IOPS type on AWS. Retained IOPS may exceed the included baseline; MongoDB recommends adjusting storage and IOPS independently afterward to optimize cost. (high confidence) (verified as of 2026-10-20) — [source](https://www.mongodb.com/docs/atlas/cluster-config/change-cluster-generation.md) - Maximum standard IOPS rise from up to 16,000 on AWS Gen1 to 80,000 on AWS Gen2, and from 100,000 on Google Cloud Gen1 to 160,000 on Google Cloud Gen2. These are overall ceilings; tier and disk size constrain individual clusters. (high confidence) (verified as of 2026-10-14) — [source](https://www.mongodb.com/docs/atlas/manage-clusters.md) - The Core comparison applies to eligible M30+ clusters on AWS and Google Cloud; Gen2 availability varies by region and excludes Azure. M10/M20 are generation-agnostic. Atlas Infinite also uses Gen2 but does not support Extended Standard IOPS. (high confidence) (verified as of 2026-10-14) — [source](https://www.mongodb.com/docs/atlas/cluster-config/change-cluster-generation.md) - Automation selects Gen2 tiers using names such as M30_GEN_2. For GCP Gen2 nodes, the operator exposes diskIOPS; changing it affects cluster cost, and its permitted maximum depends on instance size and disk size. (medium confidence) (verified as of 2026-10-14) — [source](https://www.mongodb.com/docs/atlas/cluster-config/change-cluster-generation.md) - AWS documents gp3 with 3,000 included IOPS and optional paid additional IOPS. Google documents Hyperdisk Balanced with 3,000 included IOPS and 140 MiB/s, with performance above the baseline billable. These provider rules describe underlying products, not Atlas invoice rates. (medium confidence) (verified as of 2026-10-22) — [source](https://docs.aws.amazon.com/ebs/latest/userguide/general-purpose.html) - On AWS, the Gen1 UI calls the provisioned-IOPS option Provision IOPS; Gen2 calls it High Performance IOPS. It uses a different SSD category from Standard IOPS. Extended Standard IOPS should not be confused with this option. (medium confidence) (verified as of 2026-10-20) — [source](https://www.mongodb.com/docs/atlas/customize-storage/)