RDS Cost & Rightsizing Calculator
Model RDS instance hours, storage, Multi-AZ, and Graviton against your current setup — with the storage doubling Multi-AZ causes shown separately from the compute doubling, because only one of them is negotiable.
| Instance hoursdb.m5.large, Multi-AZ x 4 | $1,039.52 |
| Storage500 GiB at $0.23/GB-month | $460.00 |
| Total | $1,499.52 |
What Multi-AZ actually costs
Multi-AZ is the right default for production. It is the wrong default for the dev, staging and QA copies that inherited the production Terraform module — and that is where this number is usually recoverable.
Levers
| Move to db.m6g.large (Graviton)Same vCPU and memory, ~11% cheaper. For PostgreSQL and MySQL this is a version upgrade, not a migration. | $110.96/mo |
| Reserved instancesIndicative band, 1yr all-upfront to 3yr. Compute only — storage is never covered. | $363.83–$644.50/mo |
| Stop non-production overnightAt half the hours. Note RDS restarts a stopped instance after 7 days, so this needs automation to re-stop. | $519.76/mo |
| Largest single lever | $519.76 |
What this model assumes
- Multi-AZ doubles storage as well as compute. The standby keeps a full copy and AWS bills it. On a large database this is the bigger half of the premium, and it is the half that never appears in a “Multi-AZ costs 2x” summary.
- PostgreSQL rates, single-engine. MySQL and MariaDB price similarly; SQL Server and Oracle carry licence components that are not modelled here at all.
- Storage is gp3 general purpose. Provisioned IOPS (io1/io2) volumes, backup storage beyond the free allocation, and cross-region snapshot copies are not included.
- Stopping RDS is time-limited. AWS restarts a stopped instance after 7 days, so the scheduling saving requires an automation that re-stops it — otherwise it quietly stops being real after a week.
- RDS instances and storage (PostgreSQL) — source, read 4 Aug 2026
US East (N. Virginia) list prices, excluding any negotiated or committed-use discount. Your effective rate is lower if you have one.
Frequently asked questions
How much does RDS Multi-AZ cost?
Roughly double, but in two places rather than one. The standby instance doubles the compute charge, which everyone expects. Storage also doubles — from $0.115 to $0.23 per GB-month — because the standby keeps a full copy and AWS bills it. On a database with a large volume and a small instance, the storage half is the bigger surprise.
Is RDS Graviton cheaper?
Yes, about 11% at the same vCPU and memory — a db.m6g.large costs $0.159 an hour against $0.178 for a db.m5.large. For PostgreSQL, MySQL and MariaDB the move is an instance class change during a maintenance window rather than a migration, which makes it one of the least disruptive savings available in RDS.
Can you stop an RDS instance to save money?
You can, but only for seven days — AWS automatically restarts a stopped RDS instance after that. Scheduling non-production databases off overnight therefore needs an automation that stops them again, otherwise the saving quietly disappears after a week. Storage keeps billing while stopped either way.
Do reserved instances cover RDS storage?
No. Reserved instances and Savings Plans cover compute only. Storage, backup storage beyond the free allocation, IOPS and data transfer are always on-demand, which is why a commitment never reduces a bill by its headline percentage.
Should development databases run Multi-AZ?
Rarely. Multi-AZ buys an availability guarantee that a development or staging database does not need, at roughly double the cost of both compute and storage. It usually ends up enabled there because the environment was created from the production Terraform module, and that is where this number is most often recoverable.
One database is easy. Two hundred is the actual problem.
Finitizer inventories every RDS instance across every account, finds the non-production databases running Multi-AZ, the x86 instances with a Graviton equivalent, and the reserved instances about to expire — then opens the change as a pull request.