EV Battery Degradation Calculator
Electric vehicle batteries lose a little usable capacity over time, and tracking that loss tells you about the pack's health and your real range. Enter the original and current usable capacity, the battery age, and the original rated range. This calculator returns the state of health, the total capacity lost, the average annual degradation rate, and your estimated current range. It works from your own measured capacities rather than an assumed degradation curve.
Battery degradation formula
State of health (%) = 100 * current capacity / original capacity
Capacity lost (%) = 100 - state of health
Annual degradation (%/yr) = capacity lost / battery age
Estimated current range = original range * state of health / 100
State of health is current over original capacity. Annual degradation is an average across the battery's life; real loss is usually faster early then slower. Range scales with state of health under similar conditions.
Battery health context
- Use measured usable capacities; many vehicles report state of health in service data.
- Degradation depends on chemistry, climate, charging habits, and use.
- Annual rate here is an average, not a constant year-on-year figure.
- Manufacturer warranties often guarantee a minimum capacity over a set period or mileage.
- Real range also varies with temperature, speed, terrain, and accessory use.
EV battery degradation: frequently asked questions
What is EV battery state of health?
State of health (SoH) is the current usable battery capacity expressed as a percentage of the original capacity when new: SoH = current capacity / original capacity times 100. An SoH of 90 percent means the pack holds 90 percent of its original energy. Capacity loss, or degradation, is simply 100 minus the state of health.
How is the annual degradation rate calculated?
Divide the total percentage capacity lost by the battery's age in years to get an average annual degradation rate. For example, 10 percent loss over 5 years is about 2 percent per year. This is an average; real degradation is usually faster early on and then slows, and it depends heavily on use and climate.
How does degradation affect driving range?
Usable range scales with usable capacity, so a battery at 90 percent state of health gives roughly 90 percent of the original range under the same conditions. This calculator multiplies your original rated range by the state of health to estimate current range. Real range also varies with temperature, speed, and driving style.
What is a normal amount of EV battery degradation?
Degradation varies by model, chemistry, climate, and charging habits, so there is no single figure, and this calculator works from your own measured capacities rather than an assumed rate. Manufacturers commonly warrant the battery to retain a defined minimum capacity, often around 70 percent, over a set period such as 8 years or a mileage limit.
How can I slow battery degradation?
Common guidance includes avoiding frequent full charges to 100 percent and deep discharges, limiting time at very high or very low states of charge, reducing exposure to extreme heat, and using fast charging sparingly. Following the manufacturer's charging recommendations for your specific vehicle is the most reliable approach.
Official sources
- U.S. Department of Energy: DOE electric vehicle battery research.
- U.S. Department of Energy and EPA: fueleconomy.gov EV range and battery.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.