Database & SQL
PostgreSQL Connection Pool Calculator
Enter PostgreSQL max_connections, application server count, and peak RPS to compute optimal PgBouncer pool size and saturation risk.
Calculations run locally in your browserTool
Example — 100 max connections · 4 app servers · 4 DB cores · 20ms · 500 RPS
Recommended total pool
9 conns
(cores × 2 + 1) capped by max_connections − 5
Per-app pool size
2 conns
total / 4 app servers
Peak concurrent demand
10.0 conns
500 RPS × 0.020s avg query
Saturation
111% — ✗ UNDER-PROVISIONED — increase pool or reduce query time
Memory ~750 MB at max_connections
Affiliate disclosure
Managed PostgreSQL deployment option. Railway provides hosted PostgreSQL alongside application deployment.
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About this tool
PostgreSQL Connection Pool Calculator
The PostgreSQL Connection Pool Calculator computes optimal PgBouncer pool size and saturation thresholds from max_connections, application server count, and query throughput.
• Calculate PgBouncer pool_size before configuring a new application tier
• Determine if current max_connections is sufficient for planned app server scaling
• Identify connection pool saturation risk at peak load
• Model connection overhead in shared_buffers for capacity planning
FAQ
What does this tool tell you?
The PostgreSQL Connection Pool Calculator computes optimal PgBouncer pool size and saturation thresholds from max_connections, application server count, and query throughput.
What affects the result most?
PostgreSQL connection limit: max_connections default 100, each connection uses ~5-10MB shared memory. PgBouncer pool_size: (db_connections - superuser_reserved) / number_of_application_servers. Transaction mode pooling: most efficient — connection returned to pool after each transaction.
How should I use the result?
The calculation is deterministic — the same inputs always produce the same output — so the most useful workflow is to vary one input at a time and see which factor moves the result most. That tells you where to focus your attention before committing to a decision.
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