Cloud Spanner Cost Calculator
Size a Spanner instance in nodes and processing units from read QPS, write QPS and storage, then price it.
About Cloud Spanner Cost Calculator
Spanner capacity is expressed either as nodes or as processing units, with 1,000 PU to a node, and each node carries a throughput budget and a storage limit at the same time. Because a write is replicated to every voting replica it consumes roughly five times a read, so write-heavy workloads hit the node count long before read QPS would. Spanner has no small end — the first node is a real monthly commitment — so knowing whether reads, writes or storage sets your node count tells you which one to optimise before adding capacity. Multi-region instances cost several times the regional rate, so confirm the node-hour price for your exact configuration in the Google Cloud pricing calculator.
Formula
Cloud Spanner Cost
nodes = max(read QPS ÷ (reads per node × target CPU), write QPS ÷ (writes per node × target CPU), storage GB ÷ storage per node), rounded up; cost = nodes × node price × hours + storage + backup.
- reads per node
- About 10,000 read QPS per node at 100% CPU
- writes per node
- About 2,000 write QPS per node — writes replicate to every voting replica
- target CPU
- Utilisation you size to, leaving headroom for spikes and for split rebalancing
- processing units
- 1,000 PU equal one node; instances below a node are sized in 100-PU steps
Worked example
With the default values below, Cloud Spanner Cost Calculator returns Nodes Required of 7. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Peak read QPSaccepts 0–10,000,000 QPS
- 40,000 QPS
- Peak write QPSaccepts 0–10,000,000 QPS
- 3,000 QPS
- Database storageaccepts 0–1,000,000 GB
- 2,000 GB
- Read QPS per nodeaccepts 100–100,000 QPS
- 10,000 QPS
- Write QPS per nodeaccepts 50–100,000 QPS
- 2,000 QPS
- Target CPU utilisationaccepts 20–90 %
- 65 %
- Storage limit per nodeaccepts 100–20,000 GB
- 4,096 GB
- Price per node-houraccepts 0–100 USD/node-hour
- 0.9 USD/node-hour
- Hours in the billing monthaccepts 1–744 hours
- 730 hours
- Storage price per GBaccepts 0–5 USD/GB-month
- 0.3 USD/GB-month
- Backup storage retainedaccepts 0–1,000,000 GB
- 1,000 GB
- Backup price per GBaccepts 0–5 USD/GB-month
- 0.1 USD/GB-month
Results
- Nodes Required
- 7 nodes
- Processing Units
- 7,000 PU
- Sizing Driven By
- Read throughput
- Monthly Cost
- $5,299.00
- Node Charge
- $4,599.00
- Storage Charge
- $600.00
- Backup Charge
- $100.00
- Read Headroom at This Size
- 12.1%
Step by step
- 1Values used
- 2Cloud Spanner Cost
- 3Nodes Required= 7 nodes
- 4Processing Units= 7,000 PU
- 5Sizing Driven By= Read throughput
- 6Monthly Cost= 5,299.00
- 7Node Charge= 4,599.00
- 8Storage Charge= 600.00
Assumptions and limits
- The result is derived only from the 12 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Cloud Spanner Cost calculated?
nodes = max(read QPS ÷ (reads per node × target CPU), write QPS ÷ (writes per node × target CPU), storage GB ÷ storage per node), rounded up; cost = nodes × node price × hours + storage + backup. Spanner capacity is expressed either as nodes or as processing units, with 1,000 PU to a node, and each node carries a throughput budget and a storage limit at the same time. Because a write is replicated to every voting replica it consumes roughly five times a read, so write-heavy workloads hit the node count long before read QPS would.
Why does Cloud Spanner Cost matter?
Spanner has no small end — the first node is a real monthly commitment — so knowing whether reads, writes or storage sets your node count tells you which one to optimise before adding capacity. Multi-region instances cost several times the regional rate, so confirm the node-hour price for your exact configuration in the Google Cloud pricing calculator.
What values do I need to enter?
This calculator takes 12 inputs: Peak read QPS, Peak write QPS, Database storage, Read QPS per node, Write QPS per node, Target CPU utilisation, Storage limit per node, Price per node-hour, Hours in the billing month, Storage price per GB, Backup storage retained, Backup price per GB. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
When should I use processing units instead of nodes?
Below one node. Granular instances start at 100 PU and step in hundreds, which suits development and low-traffic services; above 1,000 PU capacity is allocated in whole nodes anyway.