How to Calculate Your Tesla's Battery Degradation Percentage
Use the free tool — BatteryCheck
What "Battery Degradation" Means
Every lithium-ion battery loses some capacity over time and use. For a Tesla, this shows up as a drop in the rated range your car displays compared to the rated range it had when it was new. This guide walks through how to look at that number using only what your own car and paperwork show you.
How to Calculate Your Own Percentage
You will need a few pieces of information from your own car or account:
- The rated range your car shows right now
- The rated range it had when new (from your original delivery or window sticker information)
- Your current mileage
- Your model and model year
The basic idea is to compare the current rated range to the original rated range. This guide does not include example numbers because none were provided — the calculation only makes sense with the actual figures from your car.
The 8-Year / 70% Battery Warranty
Tesla's battery and drive unit warranty is commonly described as covering 8 years and guaranteeing at least 70% capacity retention during that period, depending on model. Exact terms, mileage limits, and what counts as "capacity" can vary by model and year.
This is general information, not a guarantee of your specific coverage. Confirm the exact warranty terms for your model and year directly with Tesla before assuming what is or is not covered.
What's Normal — and What We Honestly Don't Know
We do not have specific data here on what counts as "typical" degradation at a given mileage or age. If someone tells you a number without pointing to your own car's data or Tesla's own documentation, be cautious. Ask where the number comes from.
Opening a Service Case That Gets Taken Seriously
Before you contact Tesla service, gather:
- Your rated range now and when new
- Current mileage
- Model and model year
- Any service estimate you've already received, in writing
Having these numbers ready, in writing, tends to make a service conversation more concrete and specific to your car.
What to Do Next
BatteryCheck is a free tool that reads what your own car shows you — rated range now vs. new, mileage, year, and model — or a service estimate you paste in. It works from your own numbers, not assumptions. This is not a diagnosis, and it is not affiliated with Tesla. For anything specific to your warranty coverage or repair, confirm directly with Tesla.