Reserved Instances
- What it is
- A 1-year or 3-year commitment to a specific instance configuration in exchange for up to ~72% off On-Demand.
- A billing discount, not a physical reservation of hardware (unless it is a zonal RI).
- Payment options
- All Upfront (biggest discount) → Partial Upfront → No Upfront (smallest discount).
- Two flavors
- Standard RI — largest discount, can change AZ/size within the family, cannot change instance family. Can be sold on the RI Marketplace.
- Convertible RI — smaller discount, can be exchanged for a different family, OS, or tenancy.
- Regional vs Zonal
- Regional RI — flexible across AZs in a Region, no capacity reservation.
- Zonal RI — locked to one AZ, but does reserve capacity.
- In AWS Organizations
- Unused RI discounts automatically apply across all accounts under consolidated billing.
- Not to be confused with
- Savings Plans — commit to a dollars-per-hour spend, not an instance configuration. More flexible, usually the modern recommendation.
- Capacity Reservations — reserve capacity with no discount attached.