DocumentDB Cost Calculator
Estimate an Amazon DocumentDB bill across instance hours, cluster storage, I/O requests and backup beyond the free allowance.
Inputs
One writer plus up to 15 replicas sharing the cluster volume.
db.r5.large is around $0.277/hour in us-east-1.
Estimated Monthly Cost
$714.78
Instance Hours
$606.63
Cluster Storage
$25.00
I/O Requests
$80.00
Backup Storage
$3.15
Compute Share of the Bill
84.9%
Step by step
Values used
Instances in the cluster = 3 instances; Instance price = 0.2770 $/hour; Billed hours per month = 730 hours; Cluster storage in use = 250 GB; Storage price = 0.1000 $/GB-month; I/O requests per month = 400 millions; I/O price = 0.2000 $/million; Backup storage held = 400 GB; Backup storage price = 0.0210 $/GB-month
DocumentDB Cost
monthly = instances × hourly × hours + GB × storage rate + I/O millions × I/O rate + max(0, backup GB − cluster GB) × backup rate.
Estimated Monthly Cost
= 714.78
Instance Hours
= 606.63
Cluster Storage
= 25.00
I/O Requests
= 80.00
Backup Storage
= 3.15
Compute Share of the Bill
= 84.9
How it works
DocumentDB uses the same decoupled architecture as Aurora: one shared cluster volume billed once no matter how many instances read it, plus a per-request I/O charge and instance-hours for each node. Backup storage up to the size of the cluster volume is free, so only the retention window and change rate that push you past that size cost anything. Every rate is an editable input with a realistic us-east-1 default — confirm current prices with AWS for your region. Because storage is shared, adding a replica to DocumentDB only adds instance-hours and read I/O — which makes the compute share of the bill the number that tells you whether to scale out or scale up.
Formula
DocumentDB Cost
monthly = instances × hourly × hours + GB × storage rate + I/O millions × I/O rate + max(0, backup GB − cluster GB) × backup rate.
- instances
- Writer and replicas, each billed at the full instance rate
- cluster storage
- Shared distributed volume, billed once for the whole cluster
- I/O request
- One page read or write against the cluster volume
- free backup
- Backup storage equal to the cluster volume size, at no charge
Frequently Asked Questions
How is DocumentDB Cost calculated?
monthly = instances × hourly × hours + GB × storage rate + I/O millions × I/O rate + max(0, backup GB − cluster GB) × backup rate. DocumentDB uses the same decoupled architecture as Aurora: one shared cluster volume billed once no matter how many instances read it, plus a per-request I/O charge and instance-hours for each node. Backup storage up to the size of the cluster volume is free, so only the retention window and change rate that push you past that size cost anything. Every rate is an editable input with a realistic us-east-1 default — confirm current prices with AWS for your region.
Why does DocumentDB Cost matter?
Because storage is shared, adding a replica to DocumentDB only adds instance-hours and read I/O — which makes the compute share of the bill the number that tells you whether to scale out or scale up.
What values do I need to enter?
This calculator takes 9 inputs: Instances in the cluster, Instance price, Billed hours per month, Cluster storage in use, Storage price, I/O requests per month, I/O price, Backup storage held, Backup storage price. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
Are these prices current?
They are realistic us-east-1 on-demand defaults and nothing more. DocumentDB rates vary by region and instance family, so confirm each one against the AWS DocumentDB pricing page for your region.