AWS · Free tool

AWS RDS cost calculator

The line item that doubles the day Multi-AZ ships. Plug in instance, storage, replicas, and commitment to see the real monthly bill plus a side-by-side against Aurora.

Instance class us-east-1 PostgreSQL on-demand. Other regions and engines run within 5 to 10 percent. Read replicas Each replica bills at the same hourly rate as the primary. Multi-AZ deployment Doubles instance and storage hours. Standby is not readable. Storage (GB) Storage type Provisioned IOPS gp3 includes 12K free, charged above. io1 charged on every IOP. Backup retention (days) Free up to 100 percent of storage. Beyond that, $0.095/GB-mo. Commitment Discount applies to instance hours only, not storage or backups.

Estimated monthly RDS cost

$0 per year

Instance + replicas $0 primary 730 hr x $0.171/hr	Storage + IOPS $0 500 GB x $0.115/GB-mo
Backup beyond free $0 7 day retention	Multi-AZ premium $0 vs single-AZ

Instance + replicas

primary 730 hr x $0.171/hr

Storage + IOPS

500 GB x $0.115/GB-mo

Backup beyond free

7 day retention

Multi-AZ premium

vs single-AZ

Side-by-side vs Aurora	Monthly
RDS (your inputs):	$0
Aurora Standard equivalent:	$0
Aurora I/O Optimized equivalent:	$0
Cheapest option:	RDS

If your RDS bill looks high, check these first: Multi-AZ on dev and staging, gp2 holdouts, missing RI coverage, idle replicas, 35-day backup retention on large databases, and manual snapshots retained forever after database deletion.

Why RDS bills double overnight

The day production goes Multi-AZ, instance and storage hours double. The day you add a read replica, instance hours go up another 100 percent. The day backup retention hits 14 days on a database large enough to exceed the free tier, the snapshot line shows up.

List every instance, flag gp2 storage, missing RI coverage, dev instances on Multi-AZ, and snapshots on dropped databases.

Frequently asked

Why does my RDS bill double when I enable Multi-AZ?

Multi-AZ provisions a hot standby instance in a second AZ and doubles instance hours and storage. The standby is not readable, so you also pay for read replicas if you want read scale. For dev and staging, Multi-AZ is rarely worth it. For production, the cost is the price of failover SLA.
Should I be on gp3 instead of gp2 for RDS storage?

Almost always yes. gp3 includes 12,000 IOPS and 250 MB/s for free at $0.115/GB-month. gp2 charges by volume size for IOPS at $0.10/GB-month with only 3 IOPS per GB. For most databases under 1 TB, the swap saves 15 to 30 percent on storage. The change is online with no downtime through ModifyDBInstance.
How much do Reserved Instances actually save on RDS?

A 1-year No Upfront RI saves about 30 percent on instance hours. 3-year All Upfront saves about 60 percent. Storage and backup are not eligible. RIs cover the standby on Multi-AZ and read replicas of the same class.
When does Aurora cost less than RDS, and when more?

Aurora Standard charges per I/O at $0.20 per million, plus $0.10/GB-month storage. For chatty workloads, Aurora I/O Optimized at $0.225/GB-month with no I/O charges is cheaper. RDS with gp3 stays cheaper for predictable, small databases under 100 GB.
How much backup storage is free?

Backup storage equal to your provisioned database storage is free. Past that, automated backups and manual snapshots cost $0.095/GB-month. Long retention windows on large databases are the most-missed line.