Estimate cold start frequency and its effect on average latency.
Cold start frequency depends on how invocations space out relative to the idle timeout, so sparse traffic suffers most. At high invocation rates containers stay warm and the penalty becomes negligible. Serverless is least suited to low-traffic latency-sensitive endpoints, which is precisely the case where its cost advantage looks most attractive.
Serverless Cold Start
Average latency = warm time + cold start share × cold start duration
Average latency = warm time + cold start share × cold start duration Cold start frequency depends on how invocations space out relative to the idle timeout, so sparse traffic suffers most. At high invocation rates containers stay warm and the penalty becomes negligible.
Serverless is least suited to low-traffic latency-sensitive endpoints, which is precisely the case where its cost advantage looks most attractive.
This calculator takes 5 inputs: Invocations per minute, Cold start duration, Warm execution time, Container idle timeout, Provisioned concurrency. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.