Calculator inputs
Example data table
These example scenarios use the default editable rate inputs shown in the calculator. Adjust them to match your actual region and billing assumptions.
| Scenario | Billing mode | Reads | Writes | Item KB | Storage GB | Regions | Comment |
|---|---|---|---|---|---|---|---|
| API session store | On-demand | 120M monthly | 35M monthly | 2.5 | 80 | 1 | Good for bursty traffic and simple forecasting. |
| IoT ingestion pipeline | Provisioned | 150 rps | 35 rps | 1.2 | 220 | 2 | Useful when traffic is steady and replica writes matter. |
| Commerce catalog | On-demand | 240M monthly | 12M monthly | 6.0 | 350 | 2 | Larger items increase rounded request units quickly. |
Formula used
On-demand formulas
Read units = Monthly reads × ceil(Item KB ÷ 4) × Read factor
Write units = Monthly writes × ceil(Item KB ÷ 1) × Write factor × Regions
Read cost = Read units ÷ 1,000,000 × Read price
Write cost = Write units ÷ 1,000,000 × Write price
Provisioned formulas
Suggested RCU = ceil(Read RPS × Read chunks × Read factor × Buffer)
Suggested WCU = ceil(Write RPS × Write chunks × Write factor × Buffer)
RCU cost = Suggested RCU × Hourly RCU price × Hours
WCU cost = Suggested WCU × Hourly WCU price × Hours × Regions
Additional cost formulas
Storage = Storage GB × Storage price × Regions
PITR = PITR GB × PITR price × Regions
Backups = Backup GB × Backup price × Regions
Restore = Restore GB × Restore price
Streams = Stream read units × Streams price
How to use this calculator
- Select your billing mode first.
- Enter item size, read behavior, write behavior, and region count.
- For on-demand, provide monthly reads and writes in millions.
- For provisioned, provide average requests per second and a safety buffer.
- Add storage, recovery, backup, restore, and stream usage values.
- Review the editable price fields before estimating.
- Click Estimate cost to see the result above the form.
- Download CSV or PDF if you need a shareable summary.
FAQs
1) What does this calculator estimate?
It estimates request costs, storage, point-in-time recovery, on-demand backups, restores, and stream reads. It also suggests RCU and WCU capacity when you choose provisioned billing.
2) When should I use on-demand billing?
Use on-demand when traffic is unpredictable or spiky. It removes capacity planning overhead, but it can cost more than provisioned capacity for stable workloads.
3) Why does item size matter so much?
DynamoDB rounds request units by item size blocks. Larger items consume more read and write units, even if the request count stays the same.
4) How are multiple regions handled?
This estimator multiplies replicated write and stored data related costs by the region count. That gives a practical global-table style approximation for budgeting.
5) Can I change the default prices?
Yes. Every rate field is editable, so you can tune the estimator for your preferred region, table class, or internal planning assumptions.
6) Are global secondary indexes included automatically?
No. This file estimates the main workload only. If you use indexes, add their extra request and storage impact into your input values or extend the file with separate index fields.
7) What is included in the PDF export?
The PDF export contains a clean numeric summary of the calculation. It focuses on the main report lines rather than embedding the interactive chart.
8) Will this match my invoice exactly?
Not always. Real invoices can vary because of table class choices, indexes, reserved capacity details, regional prices, and vendor pricing changes. Use this as a planning estimator.