Energy
Estimate remaining battery capacity from age, mileage, and an annual degradation assumption.
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EV battery degradation estimator guide
Every lithium-ion traction battery loses a little capacity each year and a little more with every charge cycle, and this estimator turns those two effects into a single remaining-capacity figure. Enter the pack’s original capacity, the vehicle’s age in years, its odometer reading, an annual loss percentage, and a loss percentage per 10,000 miles. The tool adds the age-based loss to the mileage-based loss, caps the total at 100%, and applies it to the original capacity. Use it when sizing up a used EV, judging whether a range complaint is normal wear, or projecting how much battery a lease return will have left. Fleet telematics data puts typical degradation near 1.5–2.5% per year, with the steepest drop in the first year and a flatter curve afterwards, so the 2.5% default is deliberately conservative. Hot climates, frequent DC fast charging, and routinely sitting at 100% push a pack toward the higher end; LFP chemistry, moderate temperatures, and daily charging to 80% keep it near the lower end.
Capacity lost (%) = years × annual loss (%) + (miles ÷ 10,000) × loss per 10,000 miles (%), capped at 100%. Remaining capacity (kWh) = original capacity (kWh) × (1 − capacity lost ÷ 100).
Worked example: a 4-year-old EV with a 75 kWh pack and 48,000 miles, using 2.5% loss per year and 0.5% per 10,000 miles. Age loss = 4 × 2.5% = 10%. Mileage loss = 48,000 ÷ 10,000 × 0.5% = 4.8 × 0.5% = 2.4%. Total loss = 10% + 2.4% = 12.4%. Remaining capacity = 75 × (1 − 0.124) = 75 × 0.876 = 65.7 kWh, the figure the calculator displays. If the car was rated at 375 km when new, expect roughly 12.4% less, or about 330 km under the same conditions. Swap in a gentler 1.8% annual figure and the same car keeps 75 × (1 − 0.096) = 67.8 kWh.
Original capacity is in kilowatt-hours; use the usable figure if the manufacturer publishes one, otherwise the gross figure, and be consistent when you compare with a battery-health readout. The kWh field also accepts Wh or MWh from its unit menu. Mileage is in miles with a kilometre option; when you switch to km the tool converts at 1.609344 km per mile before applying the per-10,000-mile rate, so a car with 77,000 km is treated as about 47,800 miles. Percentages are entered as whole numbers: type 2.5, not 0.025.
This is a modelled estimate, not a meter reading. Real consumption moves with weather, occupancy, appliance age, standing charges, and tariff structure, and equipment rarely runs at its nameplate rating. Use the figure to compare options against each other, then confirm against your own bill and the manufacturer's specification before committing to a purchase. On this page the figure rests entirely on original battery capacity, vehicle age, vehicle mileage, annual capacity loss, mileage loss per 10k miles, market / jurisdiction, effective date, data source, update owner and review date, so start there if the ev battery degradation estimator returns something you did not expect.
Good to know: the two loss rates overlap in practice, because a high-mileage car has also completed more charge cycles, so do not stack an aggressive annual figure with an aggressive mileage figure unless the car has a hard life behind it. Another trap is comparing the result with the dashboard range estimate, which reacts to recent driving and temperature, not just battery health. Finally, degradation is not linear: a pack often drops 3–5% in its first year and then settles, so a 1-year-old car may read worse than this straight-line model predicts while a 7-year-old car reads better.
Energy results depend on tariffs, equipment behavior, region, weather, and installation assumptions. Verify rates and electrical decisions with the utility, manufacturer, or qualified professional.
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How it works
Estimate remaining battery capacity from age, mileage, and an annual degradation assumption. This tool explains the calculation so you can adjust the assumptions to match your situation.
Worked example
With Original battery capacity = 75 kWh · Vehicle age = 4 years · Vehicle mileage = 48000 mi · Annual capacity loss = 2.5 % · Mileage loss per 10k miles = 0.5 % → 65.7 kWh (estimated remaining battery capacity). Change an input above and this example updates with your numbers.
Common questions
Large fleet datasets show an average of roughly 1.8–2.3% of capacity per year, so a car rated at 300 miles new might lose 5–7 miles of range a year. Individual packs vary widely: heat, fast charging, and time spent at very high or very low charge move the number up, while moderate climates and 80% daily charging limits keep it low.
Yes. With the default 2.5% per year plus 0.5% per 10,000 miles, a 4-year-old car with 48,000 miles lands at 12.4% loss, or 65.7 kWh of an original 75 kWh. Anything under about 10% would be better than average; over 20% at this age suggests heavy fast charging, extreme heat, or a pack that deserves a warranty check.
Charge to 100%, note the displayed range or the energy figure in a diagnostic app, and compare with the original rating. Many cars expose a state-of-health value through the OBD port with a Bluetooth reader. Then run this estimator with the car’s age and mileage; a reading far below the estimate is a negotiating point or a reason to walk away.
Frequent DC fast charging adds heat and stress and is associated with somewhat faster capacity loss, though modern thermal management narrows the gap. Occasional road-trip fast charging has little measurable effect. If a car you are inspecting was a rideshare or fleet vehicle that fast charged daily, nudge the annual loss toward 3% in this tool.
Most manufacturers warrant the traction battery for 8 years or 100,000 miles (about 160,000 km), and many promise to repair or replace it if capacity falls below roughly 70% in that window. Use the estimator to see whether a car is trending toward that threshold before the warranty runs out.