05.01 · Concept
Cost Curves and Crossovers
Work out where serverless stops being cheaper than an always-on container, and name the fixed costs that apply before a single request.
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Serverless is cheaper only while per-request charges stay below the fixed monthly cost of keeping capacity online. The crossover comes from comparing request volume, runtime and memory against container instances, load balancers, NAT, logging and other baseline charges that exist even when no users arrive.
What this lesson answers
- when does serverless become more expensive than containers
- what fixed costs exist before serverless handles traffic
- how do I calculate a serverless container crossover
Notes
Cost Curves and Crossovers — Cost curves exist to compare fixed always-on capacity against per-request serverless billing; without them, teams often choose Lambda or containers using average price guesses and miss the traffic point where the cheaper option flips.
Key Concepts: - A simple serverless monthly cost model is , where = requests/month, = seconds/request, and = configured memory in GB.
References
Common questions
- How do I find the point where serverless stops being cheaper?
- Model serverless as a cost per request, including execution time and configured memory. Model containers as a monthly fixed cost, including the running instances and surrounding infrastructure. The crossover is where those totals match. Below that request volume, serverless tends to win; above it, steady capacity often becomes cheaper.
- Why is comparing only compute cost misleading?
- Compute is only part of the bill. A production path can include a load balancer, NAT, logging, network connectors, control plane charges or minimum running infrastructure. Some of those costs apply before application traffic exists, so a service that looks usage-based can still have a monthly floor.
- What makes serverless expensive for busy APIs?
- Serverless cost rises with each request and with how long each request runs. Higher memory settings also increase the execution portion of the bill. For a busy or slow API, that variable cost can overtake the price of keeping a small set of containers running continuously.
Short definition: what is Cost Curves and Crossovers?