Executor Requirement Calculator
Determine how many Jenkins executors you need to meet target build throughput.
About Executor Requirement Calculator
Little's Law applied to a build farm: the number of executors needed to sustain a given arrival rate equals that rate multiplied by how long each build occupies an executor. Rounding up with `ceil` ensures enough capacity to avoid a queue from forming under steady-state load — though this doesn't account for burstiness, so real deployments typically add extra headroom above this baseline.
Formula
executors = ceil(buildsPerHour × avgDurationHours)
- B_h
- Target builds per hour
- t_h
- Average build duration in hours
- E
- Executors required
Worked example
With the default values below, Executor Requirement Calculator returns Executors Required of 4. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Target Builds per Houraccepts 0.1–100,000 builds/hr
- 30 builds/hr
- Average Build Durationaccepts 0.01–1,440 min
- 8 min
Results
- Executors Required
- 4 executors
- Exact Executor Requirement
- 4.000
- Utilization at Rounded Capacity
- 100.0%
Step by step
- 1Avg duration in hours= 0.1333hr
- 2Executors (exact) = builds/hr × avg duration (hr)= 4.000
- 3Executors needed = ceil(exact)= 4 executors
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why round up with ceil instead of down?
Rounding down would leave slightly less capacity than the target throughput requires, causing queue buildup over time even under perfectly steady load; rounding up guarantees the theoretical capacity meets or exceeds demand.
Does this account for traffic bursts?
No — this is a steady-state average calculation; real build traffic is bursty (e.g. everyone pushes right before standup), so production capacity planning typically adds 20–50% headroom above this baseline to absorb bursts without long queue waits.
How does this relate to the build queue calculator?
This calculator answers 'how many executors do I need for zero steady-state queueing,' while the build queue calculator answers 'given my current executor count, how long will builds wait' — they're inverse views of the same queueing relationship.