The Commitment Spectrum

AWS offers two primary commitment discount mechanisms: Reserved Instances (RIs) and Savings Plans (SPs). Both trade flexibility for savings, but they operate on fundamentally different axes. RIs commit to specific instance families in specific regions. Savings Plans commit to a dollar-per-hour spend level across broader compute categories.

The right choice depends on three factors: workload predictability, architectural flexibility needs, and your team’s operational maturity for managing commitments.

Stable, predictable workloads favor RIs for maximum discount
Dynamic or multi-region workloads benefit from Savings Plans flexibility
Organizations with strong FinOps practices can layer both for optimal coverage