EV Battery Degradation Calculator (Battery Health & Range by Year)
Estimate an electric car battery's state of health and remaining range after any number of years, from charging habits and climate, using Geotab fleet data (about 1.5–3% capacity loss a year).
How it works
state of health (%) = 100 − annual loss × years · annual loss = 1.5% (mostly slow charging), 2.3% (average) or 3.0% (frequent high-power DC fast charging), + 0.4% in a hot climate · range now = range when new × state of health · years to 80% = 20 ÷ annual loss; to 70% = 30 ÷ annual loss
Lithium-ion batteries slowly lose capacity with time and use. Geotab's 2025 analysis of more than 22,700 electric vehicles found an average loss of 2.3% a year, about 1.5% for cars that rarely use DC fast charging and 3.0% for those that fast-charge often at high power, with hot climates adding about 0.4% a year. Fleet data show the loss is roughly linear over the first eight years, so the projection uses a straight line. Most EV battery warranties cover 70% of capacity for 8 years or 160,000 km (100,000 miles).
Worked example
An EV with 400 km of range when new, 5 years old, with average charging in a mild climate loses 2.3% a year: 100 − 2.3 × 5 = 88.5% battery health. The range is now about 400 × 0.885 = 354 km (46 km less), and at this rate it would reach 80% after 8.7 years.
Sources: Geotab — EV battery health: key findings from 22,700 vehicles (2025) · US DOE Alternative Fuels Data Center — Batteries for electric vehicles
Frequently asked questions
How fast do EV batteries degrade?
Real-world fleet data put the average at about 2% a year — Geotab's 2025 study found 2.3%. An eight-year-old EV typically keeps 80–88% of its original capacity.
Does DC fast charging damage the battery?
Frequent high-power fast charging speeds up wear: vehicles that used it for more than 12% of sessions lost about 3% a year versus 1.5% for those that rarely did. Occasional road-trip fast charging has little effect.
What does the battery warranty cover?
Most manufacturers guarantee at least 70% of the original capacity for 8 years or 160,000 km (100,000 miles), whichever comes first. A pack that drops below that within the period is repaired or replaced.
How can I slow battery degradation?
Charge mostly at home or on AC chargers, keep daily charging to about 80% unless you need the full range, avoid leaving the car at 100% or near 0% for days, and park in the shade or a garage in hot weather.
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This calculator is for educational purposes. Double-check important results before acting on them.