Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.

Battery Capacity Calculation


New Member
Jan 15, 2020
Phoenix, AZ
Searched forum for this. Found some threads, but they seemed to over complicate what is a simple calculation (unless I'm missing something). So I decided to post my own.

To calculate your total battery capacity you will need to drive your Tesla for at least 15 miles, preferably 30. At the conclusion of the trip get the following 3 numbers from the energy app on the touchscreen.
A) Average usage in watt hours. If you drove 15miles, use the 15 mile tab, 30 for 30.
B) Miles to empty.
C) % of battery left (on the trip tab).

Battery capacity = (A*B) * (100/C)

Average usage * Miles to empty = the amount of usable battery you have left in watt hours.
Multiply times 100/(percent of battery left) gives you your total battery capacity when 100% charged.

For example from my morning commute:

(210 wh/mile)*(214 miles to empty)*(100/61%battery_left) = 73,672 watt*hour or 73.67 kW*hour

Rounding errors, particularly on the % of batter left will limit accuracy, so average several measurements. But it seems to give reasonably consistent results so far (3 days, 6 data sets).

Spreadsheet link for google sheets spreadsheet if you want to copy the formulas.
Model 3 Battery Tracker




Jun 28, 2016
That is correct. But you don't need to drive anywhere, just get in your car and take the readings at any time.

Also, you won't really get that range because the rated miles calculation includes the buffer, which is below zero on the battery gauge.
Last edited:


Jun 28, 2016
At best, this calculates what the car thinks is the available capacity between 100% and 0%, not the actual usable battery capacity from full to the car stopping.
Yes, I edited my post probably after your response. The thing is, the car may stop right at zero, or several miles below zero, depending on many variables. So unless you're prepared for it, you shouldn't try to go below zero miles.

Edit: Actually, it does calculate the full capacity from full to when the car stops, but that full capacity is not all available unless you go below zero miles, which is not ever recommended.
Last edited:
  • Like
Reactions: AlanSubie4Life

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.