Same discount, different promise
AWS Savings Plans vs Reserved Instances
Both are a commitment to spend in exchange for a discount. The difference is what you are promising, and that decides which one is right far more than the headline percentage does.
Buy a Compute Savings Plan for compute. It gives up to about 66% off for a three-year commitment, or roughly 20% to 30% for one year no upfront, and it applies automatically to EC2, Fargate and Lambda in any region, family, size or architecture. Reserved Instances still matter for RDS, ElastiCache, OpenSearch and Redshift, where Savings Plans do not apply at all. The only reason to choose an EC2 Instance Savings Plan or a standard RI over a Compute Savings Plan is a slightly deeper discount on a workload you are certain will not change.
What each one actually commits you to
| Compute Savings Plan | EC2 Instance Savings Plan | Standard RI | Convertible RI | |
|---|---|---|---|---|
| You commit to | $/hour of spend | $/hour in one family and region | A specific instance config | A specific config, exchangeable |
| Covers | EC2, Fargate, Lambda | EC2 in that family and region | That service only | That service only |
| Change instance family | Yes | No | No | By exchange |
| Change region | Yes | No | No | By exchange |
| x86 to Graviton | Yes | No | No | By exchange |
| Maximum discount | ~66% | ~72% | ~72% | ~66% |
| Can be sold | No | No | Yes, in the marketplace | No |
| Applies to RDS and ElastiCache | No | No | Yes | Yes |
Maximum discounts are three-year all-upfront figures and are not what a first commitment should look like. A one-year no-upfront Compute Savings Plan is typically 20% to 30%.
How to decide, in order
- 1Clean up first. Delete the idle, rightsize the oversized, schedule the non-production. Only then look at what your compute baseline actually is. Committing before this is how companies end up paying for three years of capacity they deleted in month two.
- 2Find the floor of your compute spend. Cost Explorer, daily granularity, last 60 days, filtered to compute. The lowest sustained level is your baseline. Commit to about 70% to 80% of it, not to the average and certainly not to the peak.
- 3Buy a one-year, no-upfront Compute Savings Plan. No upfront costs a couple of percentage points against all upfront and keeps the cash. One year costs some discount against three and keeps your options. For a first commitment, both trades are worth it.
- 4Reserve the databases separately. Savings Plans do not touch RDS, ElastiCache, OpenSearch or Redshift. Those need Reserved Instances or reserved nodes, and they are the best possible candidates because a database baseline genuinely does not move. A one-year no-upfront RDS reservation is roughly 30% to 40% off.
- 5Revisit quarterly. Commitments stack, so buying more later is straightforward. Buying too much now is not undoable. Under-commit and top up.
The mistake that costs the most
Committing to three years on a first purchase. The discount looks compelling and the risk is invisible until the workload changes, which for a company under a hundred people it always does. A three-year commitment made before a re-platform, a Graviton migration or a move to Fargate becomes a bill for capacity nobody uses.
A Compute Savings Plan survives most of those changes, which is exactly why it is worth a few percentage points less discount than the alternatives. Buy the flexibility until the workload has been boring for a year.
Put numbers on it
Frequently asked questions
Do Savings Plans cover RDS?
No. Savings Plans cover EC2, Fargate and Lambda only. RDS, ElastiCache, OpenSearch, Redshift and DynamoDB all need their own reserved capacity purchases. This is the single most common misunderstanding about Savings Plans and it means database-heavy accounts frequently have a large uncovered baseline they believed was covered.
What happens if I use less than I committed to?
You pay the commitment anyway. A Savings Plan bills the hourly amount you committed to whether or not you consume it, so unused commitment is money burned. Utilisation below 95% is worth investigating; below 80% means you over-committed and the only remedy is to grow into it.
Can I cancel a Savings Plan?
No. There is no cancellation, no refund and no resale market. Convertible RIs can be exchanged for others of equal or greater value, and standard RIs can be sold in the Reserved Instance Marketplace. That resale route is the one genuine advantage standard RIs retain over Savings Plans.
Should I buy Savings Plans if my usage is growing fast?
Yes, and size to the floor rather than the trend. Growing usage means the commitment gets consumed easily, which is the low-risk direction to be wrong in. Commitments also stack, so a growing account can add a new plan every quarter and build coverage gradually without ever over-committing.
Does a Savings Plan apply automatically?
Yes. AWS applies the discount to eligible usage automatically, starting with whatever has the deepest discount rate, so there is nothing to attach and no instances to assign. That automatic application is also why an unused commitment is invisible unless you look at the utilisation report.
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Prices checked against AWS list rates on 2 August 2026. AWS changes prices; treat every figure here as a close approximation rather than a quote.
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