Getting started
Buy your first Reserved Instance
A short, safe path for a team with 1 to 10 reservations. Pick the instance, match it exactly, buy it in the console, and watch the end date.
Step 1: pick the instance
Reserve the instance that never stops.
A reservation lowers the hourly rate of usage that matches it.AWS states that it is a billing discount and not a physical instance. So the question is simple. Which instance will run for the whole term?
A discount, not a server
A reserved DB instance is a billing discount on matching usage in your account. AWS states that it is not a physical instance.
Reserve steady usage
A reservation bills every hour of the term, whether the instance runs or not. Reserve an instance that runs all day, all year.
Check for idle capacity first
A reservation on an idle instance saves nothing. Read the guide on idle capacity before you pick the instance.
You cannot cancel
AWS states that you cannot cancel a Reserved Instance after you buy it. This holds for EC2 and for RDS.
Read the guide on idle capacity before you buy. It shows how to find an instance that is too large or unused.
Step 2: match it exactly
The reservation must match the running instance.
Each service has its own match rules. The table shows what must match, what can flex, and what you can change after the purchase.
| Rule | Amazon RDS | Amazon ElastiCache | Amazon EC2 |
|---|---|---|---|
| Must match exactly | Instance family (class type), database engine, region | Instance family, cache engine, region | Instance family, region or Availability Zone (scope), platform (OS), tenancy |
| Can flex | Size within the class type by normalized units, and freely between Single-AZ and Multi-AZ, on Db2, MariaDB, MySQL, Oracle BYOL and PostgreSQL only. No size flexibility on SQL Server or Oracle License Included, and no convertible option on any engine. | Size within the family by normalized units (since October 2024), but no convertible option | Size within family via size flexibility (Standard RI, regional scope); family, size, OS, or tenancy via exchange (Convertible RI) |
| Term | 1-year or 3-year | 1-year or 3-year | 1-year or 3-year |
| Payment option | No Upfront, Partial Upfront, or All Upfront | No Upfront, Partial Upfront, or All Upfront | No Upfront, Partial Upfront, or All Upfront |
| Exchange & resale | None: no modification, no exchange, no Marketplace resale | None: no modification, no exchange, no Marketplace resale | Standard RI: AZ/scope modification, RI Marketplace resale. Convertible RI: full mid-term exchange, no resale |
Amazon RDS
- Must match exactlyInstance family (class type), database engine, region
- Can flexSize within the class type by normalized units, and freely between Single-AZ and Multi-AZ, on Db2, MariaDB, MySQL, Oracle BYOL and PostgreSQL only. No size flexibility on SQL Server or Oracle License Included, and no convertible option on any engine.
- Term1-year or 3-year
- Payment optionNo Upfront, Partial Upfront, or All Upfront
- Exchange & resaleNone: no modification, no exchange, no Marketplace resale
Amazon ElastiCache
- Must match exactlyInstance family, cache engine, region
- Can flexSize within the family by normalized units (since October 2024), but no convertible option
- Term1-year or 3-year
- Payment optionNo Upfront, Partial Upfront, or All Upfront
- Exchange & resaleNone: no modification, no exchange, no Marketplace resale
Amazon EC2
- Must match exactlyInstance family, region or Availability Zone (scope), platform (OS), tenancy
- Can flexSize within family via size flexibility (Standard RI, regional scope); family, size, OS, or tenancy via exchange (Convertible RI)
- Term1-year or 3-year
- Payment optionNo Upfront, Partial Upfront, or All Upfront
- Exchange & resaleStandard RI: AZ/scope modification, RI Marketplace resale. Convertible RI: full mid-term exchange, no resale
AWS states that for ElastiCache you choose the Region, node type, and term at purchase. You cannot change them later.
Step 3: start with low risk
Buy 1-year No Upfront first.
This option needs no upfront cash. It has the shortest commitment. The example below uses a Startup team. All figures come from the Reserver data, not from a quote.
These figures are an illustration. Your own saving depends on your instance, Region, and engine. The free Reserver Watch plan shows the math for your own fleet.
Step 4: buy it in the console
Each service has its own purchase page.
Sign in to the AWS Management Console. Follow the steps for your service. The AWS pages below list every field.
- RDS. Open the Amazon RDS console. Choose Reserved instances, then Purchase Reserved DB Instance. Pick the engine, the class, the deployment, the term, and the offering type. See the RDS purchase steps.
- ElastiCache. Open the ElastiCache console. Choose Reserved Nodes, then Purchase reserved nodes. Pick the engine, the node type, the term, and the offering type. See the ElastiCache purchase steps.
- EC2. Open the Amazon EC2 console. Choose Reserved Instances, then Purchase Reserved Instances. Pick the offering class, search, set a quantity, and add it to the cart. See the EC2 purchase steps.
Step 5: after you buy
Check the discount. Then mark the end date.
AWS states that the billing benefit applies at once to a matching running EC2 instance. You do not restart it. Check your next bill to confirm the lower rate.
Put the end date on a calendar on purchase day. AWS does not renew an EC2 Reserved Instance. When it ends, you keep the instance and pay On-Demand rates. A lapse of 6 hours costs about $3.36. A lapse of 3 days costs about $40. The cost is small for one instance. It grows with every reservation that lapses.
Check your own end dates with the free Expiry Check. For the renewal steps, read the renewal playbook. You can also queue the next EC2 purchase for the day the current one ends.
How this scales with you
The first purchase is the same at every size.
Your first purchase is one or two reservations. Buy 1-year No Upfront, in the console, and put the end date on a calendar the same day.
You hold dozens of reservations in a few accounts. One person cannot track every end date by hand. A shared expiry view stops a quiet lapse.
Thousands of reservations sit in many accounts. Each account has its own quotas and end dates. Read the guides on purchase quotas and discount sharing before you buy.
Where Reserver fits
Reserver shows what to buy and when it ends.
The Watch plan is free for one AWS account. It scans your RDS, ElastiCache, and EC2 instances. It shows a recommendation with the math, and an expiry radar for the reservations you own. You buy in the AWS console. Reserver does not buy for you.
See pricing for every plan. For the size of the saving, read how much a reservation saves.
Which term should I pick for my first reservation?
Pick 1-year No Upfront. It needs no upfront cash, and it commits you for the shortest term. RDS offers No Upfront only for a one-year term. The lowest median discount across the three services is 32%.
Do I need to restart my instance after I buy?
No. For EC2, AWS states that the billing benefit applies at once to a matching running instance. You do not need to restart it.
Can I cancel a Reserved Instance if I buy the wrong one?
No. AWS states that you cannot cancel an EC2 Reserved Instance or an RDS reserved DB instance. Only an EC2 Standard Reserved Instance can be sold on the Reserved Instance Marketplace.
Does AWS renew a Reserved Instance for me?
No. AWS states that EC2 Reserved Instances do not renew automatically. When one ends, you keep the instance and pay On-Demand rates. Put the end date on a calendar.
Can I buy an EC2 Reserved Instance for a future date?
Yes, for regional Reserved Instances. AWS lets you queue a purchase for a future date and time. Queue it for the day the current one ends. Read the guide on queued purchases.
Does Reserver buy the reservation for me?
No. Reserver shows the recommendation with the math, and you buy it in the AWS console. Reserver does not make purchases.
Sources, fetched and confirmed on 2026-10-23: Amazon RDS: Reserved DB instances; Amazon RDS: Purchasing reserved DB instances; Amazon ElastiCache: Reserved nodes; Amazon EC2: Reserved Instances; and Amazon EC2: Buy Reserved Instances.
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