Pricing for reserved capacity
What is reserved capacity?
Reserved capacity gives you the option to reserve database capacity for a one- or three-year term and in turn receive a significant discount compared to provisioned capacity pricing. A reserved capacity purchase is an agreement to pay for a minimum amount of provisioned throughput capacity, for the duration of the term of the agreement, in exchange for discounted pricing.
If you use less than your reserved capacity, you will still be charged each month for that minimum amount of provisioned throughput capacity. DynamoDB offers a partial upfront payment option for reserved capacity in which you make an upfront payment and are then charged a discounted hourly rate for the capacity for the duration of the reserved capacity term.
Reserved capacity is a billing feature and has no impact on the performance or availability of your DynamoDB tables.
Details
- Reserved capacity doesn’t require any changes to how you use Amazon DynamoDB. When computing your bill, the AWS billing system automatically applies reserved capacity rates first to minimize your costs. Any throughput you provision in excess of your reserved capacity is billed at standard rates for provisioned throughput.
- Reserved capacity is available for single-Region, provisioned read and write capacity units (RCU and WCU) on DynamoDB tables including global and local secondary indexes. You cannot purchase reserved capacity for replicated WCUs (rWCUs).
- Reserved capacity can only be used with DynamoDB Standard table class.
- Reserved capacity offers significant savings compared to provisioned capacity, typically about 54% for a one-year term and 77% for a three-year term.
- You will be charged a one-time upfront fee plus an hourly fee for each hour during the term based on the amount of DynamoDB reserved capacity you purchase.
- Partial upfront payment option provides the best effective hourly price and balances the reserved capacity payments between upfront and hourly.
- You can make a partial upfront payment for reserved capacity for one- or three-year terms. One-year reserved capacity is available in all Regions, and three-year is available in limited Regions. To learn more about pricing and Region availability, see DynamoDB Pricing for Provisioned Capacity.
- When you purchase reserved capacity, you must designate a Region, quantity, and term.
- You can monitor your reserved capacity ownership from the AWS Management Console.
When should you purchase reserved capacity?
Reserved capacity is a great option to reduce DynamoDB costs for workloads with steady usage and predictable growth over time. You can determine whether reserved or provisioned capacity best fits your needs by comparing provisioned hourly rates and the effective hourly rate of reserved capacity. In order to calculate an effective hourly rate, amortize the one-time fee over the term and add the hourly usage rate. For example, the hourly amortized cost for 100 WCUs in the US East (N. Virginia) Region can be calculated as $150.00 / 365 days / 24 hours = $0.0171 per WCU hour.
If you can predict your need for DynamoDB read-and-write throughput, reserved capacity offers significant savings over the normal price of DynamoDB provisioned throughput capacity. By purchasing capacity up front, you can save up to 54% (one-year term) or up to 77% (three-year term) over the regular hourly rates.
Reserved capacity mode might be best if you:
- Have predictable application traffic.
- Run applications whose traffic is consistent or ramps gradually.
- Can forecast capacity requirements to control costs.