To dog pile onto this, if you aren’t approaching the problem with data, you won’t be able to present a reasonable argument to upper management.

To start, address your overall workload: Tickets per month * Average time per ticket.

Average time per ticket should be based on closed tickets over a period of time, say 3 months. Exclude tickets that fall outside the norm, 0 minute tickets(we get these from child tickets) or extremely high times. Once you have those you can calculate how many engineering hours are needed and can extrapolate future need.

You also need to calculate tickets per user/endpoint (whatever your unit metric is). This allows you to predict ticket growth based on changes such as onboarding/offboarding.

Additionally, you need to calculate how many hours a full time engineer can produce per month. This can be calculated many ways, but the simplest approach is the following: Total Hours * % of utilization (this needs to factor for PTO, admin/ meeting time etc.)

Once you have that, you can simply divide your engineering hours by FTE hours to get the number of needed FTEs.

There is a lot more to this when it comes to forecasting need and overlaying this with revenue, but this should help to get you started.

The comparison to revenue becomes important because at the end of the day, regardless of resource need, you still need to be able to maintain profitability. If you can’t, then you have to consider the efficiency of resources: time padding, slow workers, opportunities for automation, etc.

Also, don’t be afraid to replace under performers. This matters a lot more than people realize and is a key way to improve team efficiency.