About this site
pebblewfm.com is built by the team behind Pebble WFM, a workforce management product for contact centres. The calculators and guides here are the maths that product runs on, taken out of the product and put on a page so anyone can use it.
Why it is free
Staffing arithmetic is not a secret and should not be behind a sign-up form. Every calculator runs in your browser, shows its working, and can be shared as a link or embedded on your own site. There are no adverts, no email gates, and nothing you enter leaves your browser. It is kept there, so a calculator picks up where you left off.
The site exists so that when a calculator is not enough, when the question becomes every interval of every week with real agents and real leave, Pebble WFM is the obvious next step. That is the whole business model, and it is why the calculators have to be good.
How the maths is checked
The formulas are the standard ones: Erlang C and Erlang A for queues, workload models for email and back office, classical decomposition for seasonality. Each is implemented once, in a small library with automated tests that pin it to published reference values and to independent methods, such as a numerical solution of the queue for Erlang A. A change that moves a result breaks a test.
Every calculator's "Show the working" panel restates the calculation with your numbers substituted, so you can follow it in a spreadsheet and disagree with it if you find a reason to. If you do, write and say so.
What is here
30 calculators and planning tools, twenty guides, and a set of staffing tables:
- Erlang C calculator
- Staffing requirement calculator
- Week planner and FTE calculator
- Shrinkage calculator
- Occupancy calculator
- Service level and ASA calculator
- Erlang A calculator
- Live chat staffing calculator
- Email and ticket staffing calculator
- Schedule efficiency calculator
- Forecast accuracy calculator
- Schedule adherence calculator
- Agent utilisation calculator
- Call abandon rate calculator
- Average handle time calculator
- Attrition rate and cost calculator
- Agent capacity calculator
- Queue pooling calculator
- Cross-training simulator
- Leave allowance calculator
- AI deflection ROI calculator
- Minimum staffing calculator for 24/7 cover
- Cost per contact calculator
- FTE to headcount converter
- Absence rate and Bradford factor calculator
- First contact resolution and repeat contact calculator
- Staffing shortfall and overtime calculator
- Outbound campaign staffing calculator
- Seasonality and monthly forecast calculator
- Intraday reforecast calculator
Contact
Corrections, questions and requests for a calculator that does not exist yet are welcome at hello@pebblewfm.com.
Stop doing this one interval at a time
Pebble WFM forecasts your demand, computes the staffing requirement for every interval, builds the roster and publishes it, with self-service for agents and a copilot that can do what a planner can. Explore a sample organisation on day one.