Database Connection Pool Size Planner
Right-size your connection pool by translating workload throughput and transaction duration into concurrent connections with optional headroom.
Examples
- 220 req/s, 45 ms transaction, burst ×3, 15% headroom ⇒ Result: 45 connections
- 120 req/s, 80 ms transaction, burst ×1.8, headroom 25% ⇒ Result: 26 connections
FAQ
How does read replica usage change this?
Split read-heavy traffic across replicas and run the calculator for each node based on its dedicated workload.
Should I include connection pool warmup?
Yes. Provision enough headroom so spikes during application bootstrapping do not exhaust connections.
What if I use serverless databases?
Serverless offerings still have concurrency limits. Use the computed value as a ceiling and apply connection pooling middleware if necessary.
Additional Information
- Result is the recommended maximum pool size rounded up to the nearest whole connection.
- Average transaction time should include ORMs, retries, and network latency to avoid under-provisioning.
- Keep the pool below the database server's max_connections and reserve capacity for background jobs.
- Monitor wait events and queue depth after deploying changes to verify assumptions.