OP 01 · Operations
Erlang C Calculator
Find how many agents you need to hit a service level or speed of answer target, with the math and a scenario table.
Tested: matches the worked examples from Call Centre Helper and Westbay Engineers.
Projects · Work Tools
Work Tools
Call center staffing math from someone who has run a call center. Each calculator runs in your browser with no signup, shows the formula with your own numbers plugged in, and had to match a published worked example to the decimal before it was allowed on the shelf.
Moe, head of quality control. He has personally napped next to every calculator on this shelf, and he approves of all of them, especially the part where the schedule has room for naps.
Card Catalog
Enter jumps to the first match.
Nothing on this shelf matches that. Try “staffing,” “abandon” or “FTE,” or ask me to build it.
The Operations Shelf · 3 tools
Call Center Operations
Three calculators for the trip from a forecast to a schedule. Every one shows the formula with your own numbers plugged in, so you can defend the answer in a meeting instead of just pasting it, and a share link carries your inputs so a coworker opens exactly what you saw.
OP 02 · Operations
Shrinkage and FTE Calculator
Itemize breaks, coaching, PTO and sick time in the units you track, get true shrinkage, then the heads and FTEs to schedule.
Tested: matches Call Centre Helper’s 84.5 days out of 260 (32.5 percent) example.
OP 03 · Operations
Erlang A Calculator
Staff for service level and abandon rate when callers hang up, side by side with the Erlang C answer.
Tested: matches Table 1 of Mandelbaum and Zeltyn’s 2005 paper.
The Colophon
What Is This Place?
It is the work side of gardenflouer.com: free calculators for the staffing math a call center runs on. Erlang C tells you how many agents a queue needs to hit its service level, Erlang A does the same once you admit that real callers hang up, and the shrinkage calculator turns agents on the phones into people on the schedule. They sit on one shelf because they are one job, getting from a forecast to a schedule you can defend. Pick a book off the shelf up top, search for a word, or pull one at random if you are feeling lucky. (Plain gardenflouer.com/tools is the link I send to coworkers.)
How Does a Tool Get on the Shelf?
Every calculator here goes through the same four steps, and nothing skips the line.
- Built by hand, from the formulas. No templates and no calculator widgets bought off a shelf (ironic, I know). Each one starts from the math itself, Erlang C, Erlang A and plain shrinkage arithmetic, written out on the page so you can follow along and check my work.
- Tested against known answers. Before a calculator goes on the shelf, an automated test runs it against answers somebody else already published. The Erlang C calculator has to reproduce Call Centre Helper’s worked example to the decimal, including the part where 13 agents land at 79.6 percent against an 80 percent target, which is a miss, not a rounding error. The Erlang A calculator has to match Table 1 of Mandelbaum and Zeltyn’s paper, and the shrinkage calculator has to land on Call Centre Helper’s 32.5 percent. If a test and a tool disagree, the tool is wrong until proven otherwise.
- No signups, no email, nothing to install. There is no account to make and no unlock code waiting in your inbox. Every calculator works the moment the page loads, and each one can copy its results or a share link, so you can hand a number to a coworker without retyping a thing.
- Your inputs stay on your device. The math runs in your browser, not on a server. A share link carries your numbers inside the web address itself, and like any address on this site, it shows up in the site’s visit counts when someone opens it. The site also counts which buttons get pressed, through Google Analytics (the privacy page explains what it records), which is how I know which calculator deserves the next round of polish.
Who Builds These?
Me! I am Christopher Robert Fox, and I have run a call center, which is where every calculator on this shelf comes from. I needed staffing math I could trust and explain out loud, and none of the free calculators I found showed the math with my own numbers in it. So these do: every step, every assumption and every rounding decision, right there on the page. Find the seam in a system, then show everyone the view from inside. There is more of the backstory on the about page, and the rest of what I build is on projects.
Can I Ask for a Tool?
Absolutely! If your job runs on a formula nobody ever explains, a forecast, an occupancy target or a schedule that never quite adds up, tell me on the contact page. New tools land here the moment they pass their tests, not a minute before, so this page will never say “coming soon.” Homework before you go: pull one random book off the shelf above and give it ten seconds. If it is not useful by then, that is on me, and I would really like to hear about it.