Aurora Serverless v2 cost: what an ACU really costs you

Quick answer

Aurora Serverless v2 bills per ACU-hour (~$0.12, where 1 ACU ≈ 2 GB RAM), scaling in 0.5-ACU steps between your min and max. A 0.5-ACU floor is ~$44/month before storage and I/O; with scale-to-zero it can drop near zero when idle. It beats provisioned Aurora for spiky or dev workloads, but a steady production database is usually cheaper provisioned with a Reserved Instance.

Aurora Serverless v2 promises "pay for what you use," and for the right workload it delivers. The confusion is the ACU — an abstract capacity unit that makes the bill hard to predict until you know how it scales and what it leaves out.

What an ACU is and what it costs

An Aurora Capacity Unit is roughly 2 GB of memory plus the CPU and networking to match. Serverless v2 adjusts capacity in fine 0.5-ACU increments based on load, between a minimum and maximum you configure. You pay per ACU-second for whatever's in use:

1 ACU                ≈ $0.12/hour  (us-east-1)
0.5-ACU floor, idle  ≈ $0.12 × 0.5 × 730 ≈ $44/month
8 ACU under load     ≈ $0.12 × 8   × hours at that level

The minimum ACU setting is the number that determines your floor. Set it too high "to be safe" and you pay for capacity you rarely use; set it realistically (or enable scale-to-zero) and the floor drops.

Scale to zero changes the math

Serverless v2 can now scale all the way to zero ACUs and auto-pause when idle, resuming on the next connection after a short delay. For development databases, internal tools, and anything that sits unused overnight, this turns a ~$44/month floor into near-zero. The tradeoff is the resume latency on the first query after a pause — fine for dev, usually not for latency-sensitive production.

Serverless v2 vs provisioned

Serverless wins: variable or unpredictable traffic, dev/test, new apps with unknown load, databases idle much of the day. You avoid provisioning for a peak you only hit occasionally.
Provisioned wins: steady, high-utilization production. The per-unit ACU rate carries a premium, so a database that runs near a constant size is cheaper on a provisioned instance — especially with a Reserved Instance discount.

For the broader managed-vs-Aurora decision, see RDS vs Aurora cost and Aurora I/O-Optimized for the I/O side of the bill.

Don't forget storage and I/O

ACU-hours are compute only. You still pay for Aurora storage (~$0.10/GB- month) and either per-request I/O (standard) or a higher storage/ACU rate (I/O-Optimized). I/O-heavy workloads often come out cheaper on I/O-Optimized despite the higher ACU rate, because the per-request I/O charges on standard can dominate.

FAQ

How is Aurora Serverless v2 priced?

Per ACU-hour, where an Aurora Capacity Unit is about 2 GB of memory plus matching CPU. In us-east-1 an ACU is roughly $0.12/hour. Capacity scales in 0.5-ACU steps between a configured minimum and maximum, and you pay for the capacity in use each second, plus storage and I/O.

What does Aurora Serverless v2 cost at minimum?

It depends on your minimum ACU setting. At a 0.5-ACU floor it's about $0.12 × 0.5 × 730 ≈ $44/month before storage and I/O. Serverless v2 can now scale to zero ACUs when idle (auto-pause), which drops the floor toward zero for development databases that can tolerate a resume delay.

Is Aurora Serverless v2 cheaper than provisioned Aurora?

For spiky or unpredictable workloads, yes — you pay for capacity only when it's needed instead of provisioning for peak 24/7. For steady, high-utilization databases, provisioned Aurora (especially with a Reserved Instance) is usually cheaper per unit because Serverless v2 carries a premium per ACU.

When should I use Serverless v2 over provisioned?

Use Serverless v2 for variable traffic, dev/test databases, new apps with unknown load, and infrequently-used databases that can scale to zero. Use provisioned for steady production load where you can commit to a Reserved Instance and benefit from the lower per-unit rate.

Does Serverless v2 still charge for storage and I/O?

Yes. ACU-hours cover compute only. You still pay Aurora storage (~$0.10/GB-month) and either per-request I/O on the standard configuration or a higher storage/ACU rate on I/O-Optimized. For I/O-heavy workloads, I/O-Optimized can be cheaper overall.

How does C3X estimate Aurora Serverless v2?

C3X prices an aws_rds_cluster in serverless mode from its minimum capacity as the baseline ACU floor, and treats burst capacity and I/O as usage-driven — so you see the floor cost before deploying and can model peaks in c3x-usage.yml.

What to do next

The lever you control is the minimum ACU (and whether to enable scale-to-zero). C3X prices an aws_rds_cluster in serverless mode from its capacity floor, so you can see the monthly cost of a given minimum before you set it, and compare it against a provisioned instance on the same page. The quickstart runs it on your Terraform in minutes.