dynamodb pricing calculator

How DynamoDB Pricing Works

DynamoDB pricing is made up of a few building blocks: request charges, capacity charges (if provisioned), storage, backup, and data transfer. The calculator above combines these components to give you a practical monthly estimate you can use for architecture planning, budgeting, and optimization reviews.

1) Request Costs (On-demand Mode)

On-demand mode bills you based on the number of read and write request units consumed. This works well when traffic is unpredictable or bursty. You pay for what you use, and DynamoDB handles scaling automatically.

• Read request units are billed per million requests.
• Write request units are billed per million requests.
• Standard-IA generally lowers storage price, but request prices are usually higher.

2) Capacity Costs (Provisioned Mode)

Provisioned mode bills per RCU/WCU per hour. If your workload is steady, provisioned capacity can be cheaper than on-demand. In many teams, autoscaling is used to tune capacity up and down across the day while keeping costs under control.

• RCU = Read Capacity Unit
• WCU = Write Capacity Unit
• Total monthly capacity cost = (RCU rate × RCUs + WCU rate × WCUs) × hours

3) Storage and Backup

Storage is billed by GB-month and includes table data plus secondary indexes. Backup storage is billed separately. If your retention policy is long and your data changes frequently, backup can become a meaningful portion of your total bill.

When to Choose On-demand vs Provisioned

There is no one-size-fits-all answer. Your best mode depends on traffic pattern, predictability, and operational preference.

• Choose On-demand when traffic is spiky, unknown, or rapidly changing.
• Choose Provisioned when you have stable throughput and want tighter cost predictability.
• Use autoscaling if traffic has known daily peaks and valleys.

Practical Cost Optimization Tips

Model access patterns carefully

Poor key design can cause unnecessary reads and writes. A strong partition/sort key model can reduce both latency and cost.

Use the right table class

If data is infrequently accessed but must remain online, Standard-IA may reduce total spend despite higher request pricing.

Keep item size small

Larger items can consume more capacity and storage. Store only what your query paths truly need.

Review index strategy

Global secondary indexes are powerful but not free. Every write to an indexed attribute can multiply write costs.

Track backup growth

Backups can quietly expand month over month. Set lifecycle and retention standards early.

What This Calculator Includes (and What It Does Not)

• Included: on-demand request costs, provisioned capacity costs, table storage, backup storage, and outbound transfer estimate.
• Not included: free tier credits, reserved capacity agreements, global table replication details, DynamoDB Streams consumers, and taxes.

This makes it ideal for quick planning and comparison. For production finance sign-off, verify current rates in the official AWS Pricing page and Cost Explorer.

Example Use Case

Suppose your app expects 200 million reads, 75 million writes, 50 GB of storage, and 20 GB of backups in a month. Plugging those values into on-demand mode gives a straightforward estimate that product and engineering can review together before launch.

Final Thoughts

A DynamoDB cost estimate is most useful when paired with performance and reliability goals. Use this calculator early in design, revisit it after load testing, and then keep it updated with real CloudWatch usage. That habit alone can prevent most billing surprises.