Practical guide
Savings Plans sizing: separate steady demand from bursts
estimate Savings Plans commitment coverage for baseline usage. Includes a worked example, calculator scope, and practical questions.
Updated · Sources checked
Size a commitment around eligible usage that persists
A Savings Plan exchanges an hourly spending commitment for eligible discounted usage. A large monthly average can conceal quiet hours in which part of the commitment is unused. Start with a stable eligible baseline and evaluate burst usage separately.
The calculator compares an EC2 On-Demand rate with an effective offered rate. It does not simulate AWS’s hourly allocation across services, select a commitment amount, or guarantee that projected usage will consume it.
Worked example: baseline and business-hour bursts
Suppose an application needs two identical instances continuously and adds four instances for eight hours on 22 working days. In a 730-hour planning month, baseline usage is 2 × 730 = 1,460 instance-hours.
The burst contributes 4 × 8 × 22 = 704 instance-hours. Total usage is 2,164 hours, but that average does not mean the application needs almost three instances in every hour. During quiet periods it still needs only two.
Use the two-instance baseline in the effective-rate calculator when investigating a fully utilized commitment scenario. Estimate the 704 burst hours separately at the applicable uncovered rate unless you have evidence other eligible workloads absorb unused hourly commitment.
This example identifies usage shape rather than prescribing a dollar-per-hour commitment. Convert eligible usage using the actual plan’s discounted rates and coverage rules before evaluating an offer.
Recheck the baseline after planned changes
Rightsizing, migrations, shutdown schedules, and architecture changes can all reduce future eligible usage. A commitment that fits last month’s workload may not fit the workload after an optimization already on the roadmap.
Preserve hourly utilization and coverage reports when validating a proposal. Monthly totals alone cannot show whether high daytime demand compensates for low overnight usage under hourly commitment rules.
The calculator omits upfront payments for the Savings Plan scenario and does not model unused commitment or uncovered mixed-service usage. Include payment terms and hourly commitment economics separately before any purchase.
Frequently asked questions
Can I size a plan from monthly average spend alone? That can hide underused hours. Examine the eligible hourly baseline.
Does bursting make all usage unsuitable for a plan? No. A persistent baseline can still be evaluated separately from variable demand.
Calculate your scenario
Use the ec2 savings plan calculator. Keep the displayed region, pricing date, billing units, and exclusions alongside your result. The arithmetic examples above illustrate usage or explicitly hypothetical rates; they are not AWS quotes.
Source
Billing structure checked against official AWS documentation on September 6, 2026.