AWS Savings Plans & Reserved Instances for Lambda and RDS — Sydney MySQL Quote

TL;DR

• Lambda: only Compute Savings Plans apply, up to ~17% off duration and Provisioned Concurrency; requests aren't discounted.
• RDS: Reserved Instances save up to ~69%; Database Savings Plans save less (up to 20%/35%) but are flexible.
• A small Sydney RDS MySQL on a 3-yr All Upfront RI costs ~$479 (t4g.micro) or ~$860 (t4g.small) in total.
• 10 GB and 20 GB cost the same, because RDS gp3 storage has a 20 GiB minimum.
• Verdict: use RIs for a steady RDS instance, and run on-demand for a couple of weeks before paying upfront.

Savings Plans for AWS Lambda

Only Compute Savings Plans cover Lambda. EC2 Instance, SageMaker and Database Savings Plans do not.

Lambda charge	Covered by Compute SP?
Duration (GB-s), x86 and Arm/Graviton	✅
Provisioned Concurrency (both the PC charge and its duration)	✅
Requests ($0.20 per 1M)	❌
Ephemeral storage above 512 MB, data transfer	❌
Lambda@Edge	❌
Free tier	Used up first; the plan doesn't touch it

How the commitment is applied

Step	What happens
1	You commit to a $/hour amount (e.g. $0.83/hr), measured in discounted Savings Plan prices
2	Each hour it is applied to eligible usage across the account, or the org if sharing is on, highest discount % first. EC2 (up to ~66%) and Fargate (~52%) are covered before Lambda (~17%)
3	Usage above the commitment is billed at on-demand rates
4	Commitment you don't use in an hour is lost; it doesn't carry over

Example: at ~17%, a $0.83/hr commitment covers about $1.00/hr of on-demand Lambda duration.

Term / payment	Approx. Lambda discount
1-yr, No Upfront	~12%
3-yr, All Upfront	~17%

Practical guidance

• Commit only to your baseline. Lambda usage is spiky, so size the plan to the lowest steady hourly spend, not the average.
• Optimise first, because these often save more than 17%:
  • Move to Arm/Graviton (~20% cheaper per GB-s).
  • Right-size memory (AWS Lambda Power Tuning).
  • Cut cold starts and idle wait time.
• If request charges dominate your bill, a Savings Plan does little. Batch invocations instead.
• To size it, use Cost Explorer → Savings Plans → Recommendations with type Compute and a 30/60-day look-back, then watch the Utilization report.
• If you also run EC2 or Fargate, they use the commitment first, so plan the total commitment with all three in mind.

Savings Plans and Reserved Instances for RDS

RDS has both: long-standing Reserved Instances, and Database Savings Plans (launched late 2025).

	RDS / Aurora Reserved Instances	Database Savings Plans
Discount	Up to ~69% (3-yr All Upfront), ~30–45% on 1-yr	Up to 20% provisioned, up to 35% serverless
Term / payment	1 or 3 yr; No, Partial or All Upfront	1 yr, No Upfront only
What you commit to	A specific engine, instance family, region and Single-AZ or Multi-AZ deployment	A $/hour amount
Flexibility	Size-flexible within a family for MySQL, MariaDB, PostgreSQL, Aurora and Oracle BYOL. Not for SQL Server or license-included Oracle	Change family (r7g→r8g), region or engine (RDS Oracle→Aurora PG, RDS→DynamoDB) and keep the discount
Aurora Serverless v2	❌	✅ (this is the 35% case)
Other services covered	RDS / Aurora only	Aurora, RDS, DynamoDB, ElastiCache, DocumentDB, Neptune, Keyspaces, Timestream, DMS, OpenSearch
Storage, I/O, backups, data transfer	❌	❌

Which to pick

Your situation	Pick
Stable prod DB that won't change family or engine for 1–3 years	RI. The discount is far bigger
Upgrading instance generations soon, migrating engines, or might move region	DB Savings Plan
Running Aurora Serverless v2	DB Savings Plan. RIs can't cover it
Mixed: a steady core plus changing or serverless usage	Both. RIs apply first, then the Savings Plan covers what's left

Notes:

• Right-size first, and move to Graviton (r7g/r8g) if your engine supports it, before committing.
• The Database Savings Plan bills the full commitment every hour, used or not, so size it to your baseline.
• Not every instance type qualifies. Check the eligible list for your types and engines before buying.
• Cost Explorer has separate RI and Savings Plans (type Database) recommendation reports. Compare both.

Quote: small RDS MySQL in Sydney, 3-yr All Upfront

Prices are from the AWS Price List API for ap-southeast-2 (published 2026-10-01). They are USD, exclude GST, and assume Single-AZ with gp3 storage.

Instance cost over 3 years (26,280 hours)

Instance	vCPU / RAM	On-demand $/hr	On-demand 3 yr	RI 3-yr All Upfront	Saving
db.t4g.micro	2 / 1 GB	0.025	$657	$380	42%
db.t4g.small	2 / 2 GB	0.051	$1,340	$761	43%
db.t4g.medium	2 / 4 GB	0.102	$2,681	$1,522	43%
db.t3.micro (x86)	2 / 1 GB	0.026	$683	$395	42%

Total: instance + storage

RDS MySQL gp2/gp3 has a 20 GiB minimum, so a 10 GB database is billed as 20 GB. Storage can't be reserved: 20 GB × $0.138 × 36 months = $99.36 (~$2.76/month, billed monthly).

Instance	10 GB (billed as 20 GB)	20 GB	Monthly equivalent	On-demand for comparison
db.t4g.micro	$479.36	$479.36	~$13.32	$756
db.t4g.small	$860.36	$860.36	~$23.90	$1,440
db.t4g.medium	$1,621.36	$1,621.36	~$45.04	$2,780

Not included

• Backups: free up to 100% of provisioned storage (20 GB), then $0.095/GB-month.
• Multi-AZ: roughly doubles instance and storage cost, and the RI must be bought as Multi-AZ to match.
• t4g CPU credits: RDS runs burstable instances in Unlimited mode, so sustained CPU above the baseline is billed as extra credits.
• Data transfer out: billed separately.

Recommendation

If you're not sure, choose db.t4g.small. MySQL 8 on 1 GB of RAM (t4g.micro) works only for very light loads. Run on-demand for a couple of weeks to confirm the size before paying upfront. RDS RIs are size-flexible within the t4g family, but they can't be refunded or cancelled.

Related

• AWS Savings Plans vs Reserved Instances for EC2 — Sydney t4g / t3a
• AWS Storage Price Sydney

Sources

• Introducing Database Savings Plans for AWS Databases
• Savings Plans FAQ
• Amazon RDS for MySQL Pricing
• Reserved DB instances for Amazon Aurora
• AWS Price List API — AmazonRDS ap-southeast-2