The ever analytical Troy has posted a summation here on TMC. Seems the usable battery is around 78.3 kWh and the pack is a few kWh larger at 80.5 kWh... and larger than the S75*!

"1. The Model 3 large battery is 80 kWh. To be precise, the actual capacity is 80.5 kWh based on this calculation:

Total pack capacity = 350 V * 230 Ah= 80,500 Wh = 80.5 kWh

Total Voltage of Battery Packs: 350 Volt (source is page 3 here)

Battery Energy Capacity: 230 Ah (source is page 3 here)

The document doesn't say that 230 is 230 Ah, however, I found another example here from another car that shows the unit for "Battery Energy Capacity" is Ah.

2. Model 3 LR usable capacity is more than Model S 85/85D/P85D.

Usable capacity is 78.3 kWh (source: page 6 footer). This is more than the usable capacity of the Model S 85, 85D, P85D. Those have 77.5 kWh usable capacity (source). At that time Tesla was over advertising battery pack sizes. This problem only affected the 85 and 90 kWh packs. Both of these packs have less than advertised capacity. Tesla later corrected this problem with the 75 and 100 kWh packs.

Tesla doesn't want to remind people that the Model 3 LR has more battery capacity than the 75 and 85 kWh Model S versions. That seems to be the reason why they are not using the Model 3 80/80D/P80D name scheme anymore. However, I don't know how this will work because Model 3 LR or Model 3 Standard will be very confusing when they upgrade the battery sizes."

* Recent interweb posting included a picture of a new S75 car with a battery label indicating an 85kWh pack.

"1. The Model 3 large battery is 80 kWh. To be precise, the actual capacity is 80.5 kWh based on this calculation:

Total pack capacity = 350 V * 230 Ah= 80,500 Wh = 80.5 kWh

Total Voltage of Battery Packs: 350 Volt (source is page 3 here)

Battery Energy Capacity: 230 Ah (source is page 3 here)

The document doesn't say that 230 is 230 Ah, however, I found another example here from another car that shows the unit for "Battery Energy Capacity" is Ah.

2. Model 3 LR usable capacity is more than Model S 85/85D/P85D.

Usable capacity is 78.3 kWh (source: page 6 footer). This is more than the usable capacity of the Model S 85, 85D, P85D. Those have 77.5 kWh usable capacity (source). At that time Tesla was over advertising battery pack sizes. This problem only affected the 85 and 90 kWh packs. Both of these packs have less than advertised capacity. Tesla later corrected this problem with the 75 and 100 kWh packs.

Tesla doesn't want to remind people that the Model 3 LR has more battery capacity than the 75 and 85 kWh Model S versions. That seems to be the reason why they are not using the Model 3 80/80D/P80D name scheme anymore. However, I don't know how this will work because Model 3 LR or Model 3 Standard will be very confusing when they upgrade the battery sizes."

* Recent interweb posting included a picture of a new S75 car with a battery label indicating an 85kWh pack.