EC2 Auto Scaling adds reservations-then-balanced AZ distribution
Amazon EC2 Auto Scaling introduces a new Availability Zone distribution strategy called reservations-then-balanced. This strategy prioritizes launching instances into pre-purchased capacity reservations before distributing remaining capacity across Availability Zones. It helps maximize utilization of reserved capacity while maintaining Auto Scaling's resilience, and is available today in all AWS commercial Regions.
- →New reservations-then-balanced AZ distribution strategy
- →Configure reservations-then-balanced via Auto Scaling group settings
- →No additional charge for reservations-then-balanced strategy
- →Global availability in AWS commercial Regions
Features (1) ›
- New reservations-then-balanced AZ distribution strategy
EC2 Auto Scaling now supports a reservations-then-balanced strategy, prioritizing instance launches into capacity reservations before distributing remaining capacity evenly across Availability Zones. This feature helps maximize the utilization of pre-purchased capacity, such as On-Demand Capacity Reservations and Capacity Blocks.
Enhancements (1) ›
- Configure reservations-then-balanced via Auto Scaling group settings
Users can configure the new reservations-then-balanced strategy by setting the capacity distribution strategy within the AvailabilityZoneDistribution configuration of their Auto Scaling group. Configuration can target capacity by Capacity Reservation Group ARN or individual Capacity Reservation IDs.
Notes (2) ›
- No additional charge for reservations-then-balanced strategy
There is no additional charge for using the reservations-then-balanced strategy. Users will continue to pay standard EC2 pricing for their reservations and any instances launched by the Auto Scaling group.
- Global availability in AWS commercial Regions
The reservations-then-balanced strategy is available starting today in all AWS commercial Regions. Users can learn more in the Amazon EC2 Auto Scaling User Guide.
https://aws.amazon.com/about-aws/whats-new/2026/06/ec2-auto-scaling-res-then-balanced/