Forecasting headcount for your support team

Wondering where that spreadsheet for calculating how many people (and managers!) a support team needs to handle their workload? It's a popular one in Support Driven and gets asked about pretty frequently. Here it is, courtesy of Bill Bounds:

History of this spreadsheet
At the first Support Driven conference, the 2016 SUPCONF in San Francisco, Bill Bounds gave a talk to help support leaders manage conversations around resourcing. He included this spreadsheet to help build a basic headcount model to better inform those discussions, and SD community members frequently reference it.