mission-finops --commitment-calculator

AWS commitment stacking calculator.

Model all four AWS compute commitment instruments against one workload at the same time. Reserved Instances and Savings Plans each get an effective cost, a break-even utilization, and a stranding exposure, side by side, on one screen.

Most calculators price one instrument in isolation. The decision that goes wrong is rarely which single instrument to buy. It is how much to commit across several, and what happens to that commitment when usage drops. That is the question this tool is built around.

Rates entered below are defaults last verified on August 30, 2026. They are starting points, not authoritative prices. Confirm each rate against the AWS Reserved Instance pricing page and the Savings Plans pricing page for the specific instance, region, term, and payment option before relying on any figure. Results are estimates based on the values you enter.

How to read this. Break-even utilization is the ceiling: run below it and the commitment costs more than on-demand. Stranding exposure is the floor: it is what a drop in usage costs you over the rest of the term. A commitment worth buying has a break-even you are confident of clearing and a stranding exposure you can absorb if you are wrong. This tool shows both for all four instruments so the comparison is like for like.

Workload and pricing

On-demand rate (USD per hour) The published on-demand price for the instance you would otherwise run. Region-specific: read it from the on-demand pricing page for your region.

Default is an example rate. Verify at EC2 on-demand pricing.

Commitment term Reserved Instances and Savings Plans are sold for a one year or three year term.

Payment option All Upfront pays the whole term in advance and has no recurring hourly rate. No Upfront pays nothing in advance and bills an hourly rate for the term. Partial Upfront splits the two. All Upfront typically earns a better rate than No Upfront, so set the discount fields below from the AWS pricing page for the payment option chosen here.

Share of commitment paid upfront (percent) How much of the total committed cost is the one-time upfront payment. Shown because you selected Partial Upfront. All Upfront is treated as 100 percent, No Upfront as 0 percent. This changes the cash-flow split shown per instrument, not the amortized break-even utilization.

Discount per instrument

Discount depth trades against scope flexibility. The narrowest-scope instrument earns the deepest discount, the widest-scope instrument the shallowest. Enter the effective discount versus on-demand for each, from the AWS pricing page for that instrument, term, and payment option. Defaults are a plausible spread, not quotes: replace them with your own quoted rates. Last verified August 30, 2026: Reserved Instance pricing, Savings Plans pricing.

Zonal Reserved Instance discount (percent) Narrowest scope, deepest discount: a specific instance type in a specific Availability Zone.

Default is an example spread, not a quote. Last verified August 30, 2026 against Reserved Instance pricing.

Regional Reserved Instance discount (percent) Size-flexible within the instance family in a region.

Default is an example spread, not a quote. Last verified August 30, 2026 against Reserved Instance pricing.

EC2 Instance Savings Plan discount (percent) One instance family in one region, flexible across size, operating system, and tenancy.

Default is an example spread, not a quote. Last verified August 30, 2026 against Savings Plans pricing.

Compute Savings Plan discount (percent) Widest scope, shallowest discount: flexible across family, size, and region, and also covers Fargate and Lambda.

Default is an example spread, not a quote. Last verified August 30, 2026 against Savings Plans pricing.

Expected utilization

Expected utilization The share of the 730 hour month you expect the covered capacity to actually run. Drag to see where the commitment turns from gain to loss. A month is assumed to be 730 hours throughout.

85%

Or enter utilization as hours per month Bound to the slider above. 730 hours is a fully used month.

Effective cost per instrument

Ordered most specific first, the order AWS applies discounts in.

A deeper discount buys a narrower scope. The instrument with the largest saving here may not be the one that fits the workload's actual volatility: a zonal Reserved Instance earns the most but locks to one type in one Availability Zone, while a Compute Savings Plan earns the least and flexes across family, size, and region. Match the scope to how much the workload moves, then compare the numbers.

Stranding exposure at 85% utilization

Break-even is the ceiling, stranding is the floor. These figures use the Compute Savings Plan as the reference commitment, since it is the broadest and the one most likely to be over-bought. Net gain is versus paying on-demand for the same run hours.

Net monthly gain or loss

Exposure over remaining term

Gain turns to loss below

utilization

Application order: most specific first

AWS evaluates commitments every hour and applies the most specific applicable discount first, then works outward. This is why owning several instruments at once can leave one of them unused in a given hour: a more specific commitment already covered the usage. The four are rendered above in the order AWS applies them.

Zonal Reserved Instance: a specific instance type in a specific Availability Zone. The only instrument that also carries a capacity reservation.
Regional Reserved Instance: size-flexible within the instance family in a region.
EC2 Instance Savings Plan: one instance family in one region, flexible across size, operating system, and tenancy.
Compute Savings Plan: flexible across instance family, size, and region, and also covers Fargate and Lambda.

Exit paths

Standard Reserved Instances can be listed for sale on the AWS Reserved Instance Marketplace, subject to AWS eligibility requirements, which change over time. Convertible Reserved Instances and Savings Plans have no resale path: the commitment runs to the end of its term.

Confirm current Marketplace eligibility in the AWS Reserved Instance Marketplace documentation before assuming an exit exists.

These are estimates based on the values you enter, not quotes or authoritative prices. Confirm every rate on the relevant AWS pricing page for your region, term, and payment option.

Method and sources

The break-even model is one unified formula applied per instrument at that instrument's discount rate. A month is 730 hours. A term is 8,760 hours for one year or 26,280 hours for three years. The upfront amount is amortized across the full term to an hourly figure, added to the recurring hourly rate, and multiplied back up to a monthly commitment cost. Break-even utilization is that monthly commitment cost divided by what the same hours would cost on-demand, which for an amortized commitment works out to one minus the discount: a 30 percent discount breaks even at 70 percent utilization. The upfront and recurring split changes the cash-flow figures per instrument, not that break-even.

Last reviewed: August 30, 2026.

Independent educational guidance from Mission FinOps. Not affiliated with or endorsed by Amazon Web Services. This is not financial advice or a purchase recommendation.