Minimum instances
5
Infrastructure Sizing Calculator
Estimate instance count for expected traffic with safety margin and optional redundancy.
Calculator
Sizing output
Recommended instances
7
Total provisioned capacity
1,750 RPS
Estimated headroom
550 RPS
Recommendation includes selected safety margin and optional redundancy instance.
What this calculator solves
It converts traffic targets into practical instance counts with room for variability and failover.
Formula
instances_min = ceil(expected_rps / capacity_per_instance)
instances_margin = ceil(expected_rps * (1 + margin_pct/100) / capacity_per_instance)
instances_recommended = instances_margin + redundancyUse margin to absorb variability and include redundancy if one instance failure must not breach throughput targets.
Example
For 1200 RPS target with 250 RPS per instance and 20% margin, base recommendation is 6 instances. With redundancy enabled, recommendation becomes 7.
FAQ
Should I size with average or p95 load?
Use expected peak load for operational safety.
Can one instance have variable capacity?
Yes. This calculator assumes a stable tested average.
Is one redundancy instance enough?
It depends on your availability targets and fault domains.
Related tools
How it works
The calculator divides target throughput by per-instance capacity, then applies safety margin and optional resilience buffer to recommend instance count.
Formula
base_instances = ceil(expected_rps / capacity_per_instance)
recommended = ceil(base_instances * (1 + safety_margin_pct/100))Use production-like capacity benchmarks for more accurate sizing recommendations.
Example
At 1200 RPS, 250 RPS per instance and 20% margin, recommendation starts around 6 instances.
FAQ
Can I include redundancy?
Yes, add extra margin or use resilience options in your deployment model.
Should capacity be p95-based?
Prefer p95-like sustainable capacity to avoid optimistic estimates.
Is this enough for autoscaling?
It provides baseline sizing; autoscaling policies still need runtime telemetry.