Background jobs / Capacity calculator
Backlog Drain-Time & Worker Capacity
Can this queue clear before the deadline, or does incoming work consume all available capacity?
Interactive calculations run in your browser; the initial example is pre-rendered. There are no accounts, uploads, or live queue connections. Inputs stay in page memory; the site does not persist them, put them in URLs, or send them to analytics. A worksheet download includes only what you explicitly export.
Capacity estimate
Effective capacity
16 jobs/s
Limited by worker slots
Net drain rate
6 jobs/s
Capacity minus new arrivals
Drain time
33.33 min
Steady-state estimate, not a promise
Workers for deadline
9
Total workers, not additional workers
- Worker-only capacity
- 16 jobs/s
- Capacity required by the deadline
- 16.67 jobs/s
- Backlog at the deadline
- 1,200 modeled jobs
- Arrival load / capacity
- 62.5%
The suggested worker count meets the arithmetic target, but adds no safety margin for bursts, variance, or worker startup. If capacity exactly equals arrivals, there is no room to absorb a new backlog.
Inspect the arithmetic
worker capacity = workers * slots / mean service time
effective capacity = min(worker capacity, downstream cap)
drain time = backlog / (effective capacity - arrivals)
required capacity = arrivals + backlog / deadline
Assumptions and limits
- Constant arrival rate and mean service time; each job occupies one slot until it completes.
- The downstream limit is effective jobs per second, not raw API requests per second.
- Workers scale linearly until the stated downstream limit; startup, contention, retries, and failures are not modeled.
- This fluid estimate does not predict latency percentiles or guarantee a deadline under bursty traffic.