Trying to Understand Energy Costs

New Tesla Model 3 LR owner.  Love all the data available on TeslaFi, but trying to understand my true energy costs.  The drive listings give you costs per trip, but when added up, and including the losses from the sleep sessions, parking, conditioning, and phantom drains, it still doesn't add up to what's listed as "charger costs".  I know we can't calculate regenerative braking adds, but some of these figures aren't even close. I know, you can't track efficiency variables (climate, terrain, heavy peddle driving, etc.)., but what figure should I subtract out from my monthly home electric bill every month for Tesla usage?  Just the costs associated with whats leaving the Charger?