EV Battery Degradation Calculator
Estimate EV battery capacity loss based on charge cycles, temperature exposure, age, and charging habits. Predict replacement timeline.
About this calculator
This calculator estimates how much capacity an EV battery has lost using a simplified lithium-ion degradation model with two additive components. Cycle Degradation adds about 2% capacity loss per 100 full charge cycles (a full discharge-and-recharge), independent of time. Calendar Degradation adds about 1.5% per Years Owned, but that rate is itself scaled by a temperature factor: climates averaging above 25°C (77°F) accelerate calendar aging further (reflecting the real mechanism that heat speeds up the chemical side-reactions degrading lithium-ion cells -- though the real relationship is exponential in temperature, and what this calculator uses is a piecewise linear approximation of it), climates below 10°C (50°F) get a reduced 0.8x multiplier, and climates in between use the baseline 1.0x rate -- so Average Climate Temp only visibly changes the result once it crosses one of those two thresholds; small changes within the 10-25°C middle band do nothing. Charging Habit then multiplies the combined total: Mostly Slow charging applies no penalty, Mixed adds 10%, and Mostly DC Fast adds 30%, since frequent fast charging generates more heat and lithium-plating stress inside the cells. Total degradation is capped at 40%, on the assumption a real battery would be replaced before falling further, and Range Lost scales directly with that degradation percentage against the Original EPA Range you enter.
Est. Age at 70% Capacity linearly extrapolates the current annual degradation rate forward to the total age, counted from new, at which capacity would cross 70% -- the threshold most EV battery warranties use to define end-of-life. The defaults assume a typical American driver: about 150 full cycles over four years, roughly 11,000 miles a year against the model's assumed 300-mile pack. That produces about 9% loss in four years, in line with Geotab's 2025 study of 22,700 vehicles, which puts real-world average degradation at about 2.3% a year.
Inputs
Results
Estimated Capacity
91%
Est. Age at 70% Capacity
13.3 years
How to Use This Calculator
- Enter the estimated Full Charge Cycles (approximate full discharge + recharge cycles since new).
- Set the Average Climate Temperature (°F) where the car is typically kept — heat accelerates degradation.
- Enter the number of Years Owned.
- Select your Charging Habit — Mostly Slow (Level 2), Mixed, or Mostly DC Fast.
- Enter the vehicle's Original EPA Range so Range Lost is scaled to your specific vehicle.
- Review Estimated Capacity (% of original), Range Lost in miles, and Est. Age at 70% Capacity (common warranty threshold).
How the result changes with Years Owned
| Years Owned | Estimated Capacity | Est. Age at 70% Capacity |
|---|---|---|
| 2 | 94% | 10 years |
| 3 | 92.5% | 12 years |
| 6 | 88% | 15 years |
| 10 | 82% | 16.7 years |
What each input means
- Full Charge Cycles
- Approximate full charge cycles (full discharge + recharge = 1 cycle).
- Average Climate Temp
- Average annual temperature where the car is kept, in Fahrenheit. Heat accelerates degradation. (This field stays in F in both unit systems: 50F is 10C and 77F is 25C, the model's two thresholds.)
- Years Owned
- How long you've owned the vehicle.
- Charging Habit
- Frequent DC fast charging accelerates degradation by ~30%.
- Original EPA Range
- The vehicle's EPA-rated range when new. Range Lost is scaled against this.
What each result means
- Estimated Capacity
- Current estimated battery capacity as a percentage of original.
- Range Lost
- Estimated miles of range lost from degradation, scaled against the Original EPA Range you entered.
- Est. Age at 70% Capacity
- Total age of the battery, counted from new, at which this straight-line projection puts capacity at 70% — the common warranty end-of-life threshold. Subtract Years Owned to get the time remaining.
How this is calculated
Worked example, using the default values
- Identify Input Parameters5 parametersFull Charge Cycles = 150, Average Climate Temp = 70, Years Owned = 4, Charging Habit = 1, Original EPA Range = 300 = 5 input(s) provided
- Calculate Estimated CapacityEstimated Capacity91 = 91
- Calculate Range LostRange Lost27 = 27
- Project Age at 70% Capacity30% ÷ (Total Degradation ÷ Years Owned)30 ÷ (9 ÷ 4) = 13.3
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why doesn't a small change in Average Climate Temp change my result?
The temperature factor is a step function, not a smooth curve: it stays flat at 1.0x for any average temperature between 10°C and 25°C (50-77°F), drops to 0.8x below 10°C, and only starts rising above 25°C. If your climate sits inside that flat middle band, a few degrees of change moves nothing -- you need to cross one of the two thresholds to see a difference.
How much worse is fast charging really?
The calculator applies a flat 30% multiplier to your combined cycle-and- calendar degradation if you select "Mostly DC Fast" charging, versus no penalty for "Mostly Slow (Level 2)" and a 10% penalty for "Mixed." That reflects the real mechanism where fast charging generates more internal heat and higher currents that accelerate lithium-plating and other degradation side-reactions.
Why is total degradation capped at 40%?
The model assumes a real battery pack would be replaced or the vehicle retired before degradation runs meaningfully past 40%, since most manufacturers set an end-of-life warranty threshold well above that point. The cap keeps the estimate from extrapolating into a range no real fleet data supports.
How is Est. Age at 70% Capacity calculated?
It takes your current total degradation, divides by Years Owned to get an average annual degradation rate, then projects that same rate forward to find the total age, counted from new, at which degradation would reach 30% -- the point at which capacity drops to the common 70% warranty threshold. Subtract Years Owned from the result to get the time remaining. It's a straight-line extrapolation of your current rate, not a model of how degradation accelerates or decelerates over a battery's life.
Does cycle count or calendar age matter more for capacity loss?
It depends on your usage: Cycle Degradation adds about 2% per 100 full cycles regardless of how long you've owned the car, while Calendar Degradation adds about 1.5% per year regardless of how much you've driven. A low-mileage car owned for many years accumulates more calendar-driven loss; a high-mileage car owned for a short time accumulates more cycle-driven loss.
Related Calculators
The questions that sit next to this one — chosen by subject, including calculators filed under a different category.
EV Battery Replacement Calculator
Evaluate whether replacing your EV battery is worth it. Calculate value after replacement, years of extended life, cost per mile, and get a recommendation.
Electric VehiclesEV Range Calculator
Estimate real-world electric vehicle range accounting for battery capacity, temperature, HVAC usage, and terrain conditions.
Battery StorageBattery State of Health Calculator
Calculate battery SOH from capacity fade.
Battery StorageLead-Acid vs Lithium Calculator
Compare total cost of ownership between lead-acid and lithium batteries.
Electric VehiclesEV Charging Time Calculator
Calculate how long it takes to charge an electric vehicle based on battery size, current charge level, target level, and charger power.
More in Automotive & Motorcycles.