Formula
Buffered workload = Demand × (1 + Buffer)
Productive capacity per instance = min(Window, Max runtime) × Throughput × Availability
Instances = ceil(Buffered workload ÷ Productive capacity)
What the result means
The main result is the minimum whole-instance count under the entered assumptions. Headroom is productive capacity beyond the original unbuffered demand.
Benchmark throughput with representative data. Provider quotas, startup time, dependencies, and job parallelism can impose additional limits.