Erlang Suite

Unified Erlang calculator for contact center staffing — Erlang C for queue-based service level, Erlang A for caller abandonment modeling, and Power of One sensitivity analysis. Input your volume, handle time, and agent count to see exactly how staffing levels drive service outcomes.

The Erlang Suite implements the three foundational queueing models used in contact center workforce planning: Erlang-B (trunk/channel sizing), Erlang-C (agent staffing with wait tolerance), and Erlang-A (agent staffing with abandonment).

Erlang-C methodology: Given arrival rate (λ), average handle time (AHT), and target service level (e.g., 80% in 20 seconds), compute the minimum agents needed. The model assumes Poisson arrivals, exponential service times, and infinite patience — agents are added iteratively until the service level target is met.

Erlang-A extends Erlang-C by incorporating caller abandonment (average patience θ). This is more realistic for high-volume centers where callers hang up after waiting. It prevents overstaffing that pure Erlang-C recommends.

Erlang-B calculates trunk line capacity — how many phone lines you need to handle peak concurrent calls at a given blocking probability.

When to apply: Erlang-C for interval-level staffing plans (the industry standard). Erlang-A when your center has measurable abandonment. Erlang-B for IVR port planning or network trunk sizing.