I couldn't find this info posted elsewhere, so I just wanted to share what I've observed about the "1000 free Supercharger miles" that Tesla is now awarding with referrals, and what "1000 miles" actually means in this context. In short, it simply means 400 kWh. How do I know? I went on a road trip in my Model 3 LR RWD last weekend and I started out with 1000 free Supercharger miles remaining on my account after a friend had bought a Tesla using my referral code. Then, I proceeded to use 121 kWh over 4 Supercharger charging sessions. (The 121 kWh figure was determined simply by adding up the kWh figures for each charging session shown in my Tesla account's History page). After this, the free Supercharger miles remaining on my account had dropped by 302 miles -- down to a total of 698 miles remaining. (This number can be found under the "Loot Box" in the Tesla app.) A little math reveals that the 121 kWh and 302 miles figures align perfectly with "1000 miles" actually being equal to "400 kWh". [1000 miles] * [121 kWh / 400 kWh] = 302.5 miles Furthermore, the combined "miles added" from these 4 Supercharging sessions (as shown on the car's screen at the end of each charging session) added up to 520 miles, so it's clearly not going by "miles added". In fact, this shows that these "1000 free Supercharger miles" should actually be good for ~1,720 miles of actual Supercharging in my Model 3 LR RWD. And here's one other interesting detail: Even if you're in a state that normally does Supercharger billing by the minute and not by the kWh, it still debits your "free miles" by the kWh and not by the minute. All of the above charging was done in Michigan, which normally bills by the minute, but my account history for each of these charging sessions displayed the energy use in kWh and did not show any information about charging time durations.