# Instance Right-Sizing > Depth-first rabbithole dossier for Instance Right-Sizing; source-anchored research pack. Parent: [MongoDB Atlas Cost Optimization](https://llms-explorer.com/tree/mongodb-atlas-cost-optimization/) · 2 facets · 4 facts · page: https://llms-explorer.com/tree/instance-right-sizing/ ## Measurements and reference values - [low] The predictive scaling Planner chooses the cheapest instance size that can handle the next 15 minutes of customer demand without exceeding 75% CPU, relying on Forecasters to predict demand and ensure CPU utilization stays within the 50-75% target range. Sources: https://www.mongodb.com/company/blog/engineering/mongodb-predictive-auto-scaling-an-experiment — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/instance-right-sizing-61e9864cb4/rabbithole-synthesis.md#methodology` - [high] A specific optimization action cut CPU usage by 50%, and network costs for a MongoDB M10 instance ($57/month) were analyzed for both solutions. (verified as of 2026-10-15) Sources: https://dev.to/dlondero/saving-70-000-a-year-on-atlas-mongodb-534m, https://blog.besharp.it/aws-data-transfer-costs-from-a-nutshell-to-the-calculator-through-3-real-world-scenarios/ — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/instance-right-sizing-61e9864cb4/rabbithole-synthesis.md#patterns` ## Facts and statements - [low] Instance right-sizing is often the single biggest cost lever available for MongoDB Atlas optimization. Sources: https://www.mongodb.com/docs/atlas/architecture/current/cost-saving-config.md — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/instance-right-sizing-61e9864cb4/rabbithole-synthesis.md#core` - [high] MongoDB server sizes are sold as tiers (M10, M20, etc.) that map to specific instance sizes, where each server in a replica set must use the same tier, and M30 or higher clusters are recommended for production environments while M10 and M20 may be used for low-traffic applications. Sources: https://www.mongodb.com/company/blog/engineering/mongodb-predictive-auto-scaling-an-experiment, https://www.mongodb.com/docs/atlas/sizing-tier-selection.md — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/instance-right-sizing-61e9864cb4/rabbithole-synthesis.md#core` ## Related concepts - Instance — is a part of Instance Right-Sizing - Right-Sizing — is a part of Instance Right-Sizing