Severance Payment Question

So in the letter it says, “one week base salary for every 6 months of service”, has anyone been able to confirm how they figure the “base salary”? I’m trying to calculate how much I’ll get as a Full Time employee but I don’t know what to use as the base salary. All the agents at HR tell me it’s hourly rate x 40 hours. But I just don’t know if those people know what they’re talking about, anyone been able to confirm this?