EV Battery Degradation Calculator

How to use: How This EV Battery Degradation Calculator Works

The calculator uses a simple percentage‑based model to approximate how much capacity your battery may have lost. It adds degradation from several sources and then applies that loss to your original battery capacity in kilowatt‑hours (kWh).

The core idea is to estimate a total degradation percentage, then apply it like this:

Where TotalDegradationPercent comes from the following components:

• Calendar aging: about 2.5% per year of age.
• Mileage‑related wear: about 0.5% per 10,000 miles driven.
• Charge‑cycle wear: about 0.5% per 100 full charge cycles (0.005% each).
• Climate factor: an extra adjustment from 0 to about 2%, depending on how extreme your climate is.

The calculator adds these components together to get a single degradation percentage. For example, if the age, mileage, cycles, and climate add up to 22%, the tool assumes the battery has lost 22% of its original capacity.

To keep results within a typical range for most modern EVs, the model caps the total predicted loss at 30%. That means, even if the simple formula would produce a larger number, the output will not exceed 30% capacity loss. This cap prevents unrealistic results when extreme values are entered.

Finally, the remaining capacity in kWh and the remaining percentage of original capacity are reported. This lets you connect the estimate to both energy and range. For example, going from 75 kWh to 60 kWh is also going from 100% to 80% of the original capacity.

Understanding the Calculator Inputs

Each input field represents a different aspect of battery wear. Accurate entries will lead to more realistic estimates.

Original Battery Capacity (kWh)

This is the manufacturer’s rated size of your battery pack, measured in kilowatt‑hours (kWh). Common sizes are 40 kWh, 60 kWh, 75 kWh, 82 kWh, and so on.

• Check your owner’s manual, window sticker, or manufacturer website for the official pack size.
• If your EV has a 75 kWh battery, enter 75 in this field.

Age of Vehicle (years)

Battery cells degrade over time even if the car is driven very little. This is called calendar aging.

• Use the age in years since the vehicle (or battery pack) was first put into service, not just the model year.
• Round to the nearest tenth if you want more precision. For example, 3.5 years.

Total Miles Driven (thousands)

Mileage is a rough stand‑in for how many times the battery has been charged and discharged. Higher mileage generally means more wear.

• The field expects thousands of miles, not total miles.
• If your odometer shows 60,000 miles, enter 60.
• If your odometer shows 12,500 miles, you can enter 12.5.

Charge Cycles

A charge cycle is roughly one full charge from 0% to 100%, but it can also be built up from partial charges (for example, two 50% charges).

• If you have access to battery logs or manufacturer data, use that value.
• If not, you can estimate: daily charging over three years might be on the order of 1,000 cycles.
• Enter the approximate number of full‑equivalent cycles (e.g., 800, 1,200, etc.).

Climate Factor (0 mild, 2 extreme)

Temperature has a major influence on battery health. Very hot or very cold conditions tend to accelerate degradation, especially if the car is parked outside or fast‑charged often.

• 0 – Mild, temperate climate; limited time in very hot or very cold weather.
• 1 – Moderately hot or cold climate; significant seasonal extremes.
• 2 – Very hot or very cold most of the year; frequent exposure to temperature extremes.

If you are unsure, using 1 is a reasonable middle‑of‑the‑road assumption.

Reading the two numbers you get back

The result line reports remaining capacity two ways: an absolute figure in kWh (how much energy the pack can still hold) and a percentage of the original size. The percentage is the one to watch, because that is the language warranties, resale listings, and battery-health apps all speak in.

Range roughly tracks the percentage. If a car left the factory with 75 kWh and about 250 miles of EPA range, an estimate of 61 kWh (82%) points to somewhere near 205 miles under the same weather and driving. It is not a straight line in practice — cold snaps, highway speed, and a heavy right foot all cost more than degradation does on any given day — but as a planning number the percentage transfers cleanly to range.

For context on where a given result sits:

• 92% and up is what a well-treated pack looks like in its first few years. Most of the early loss happens fast, then the curve flattens.
• 80–90% is the broad, healthy middle where the majority of EVs spend most of their lives.
• 70–80% is common on older, high-mileage cars. Daily driving is usually fine; the pinch shows up on long trips that used to be one charge and now need two.
• Below 70% is where range loss becomes hard to ignore and where many warranties allow a claim.

Most manufacturers guarantee the pack against dropping below 70% (a few use 60% or 80%) within a mileage-and-year window, typically 8 years or 100,000 miles. If your estimate lands near that line and you are still inside the warranty period, it is worth requesting an official battery health check rather than relying on this ballpark.

Walking through one estimate

Take a four-year-old crossover with a 75 kWh pack, 60,000 miles on the odometer, roughly 800 charge cycles logged, and a climate factor of 1 for a place with real summers and real winters. Here is how the four components stack up:

• Calendar aging: 4 years × 2.5% = 10.0%
• Mileage wear: 60 (thousand) × 0.05% = 3.0%
• Cycle wear: 800 × 0.005% = 4.0%
• Climate: 1.0%

Adding them gives 18.0% total loss, comfortably under the 30% cap, so no clipping happens here. Applying that to the pack:

So the calculator reports about 61.5 kWh remaining, or 82% of original. In plain terms: a car that used to see roughly 250 miles of range would now plan for something closer to 205, which for most daily commuting and errands is barely noticeable — the difference mainly shows up on the occasional long haul. Notice that calendar aging alone accounts for more than half the loss; for a car this age, time in service matters more than the miles or the charging pattern, which is typical of how EV packs actually wear.

Comparison Table: Example Degradation Scenarios

The table below shows some simplified, hypothetical examples to give you a sense of how age and mileage might relate to remaining capacity under typical conditions. These values are approximate and for illustration only.

Real‑world values can be higher or lower than these ranges. Some EVs retain over 90% capacity after many years, while others may degrade faster depending on chemistry, thermal management, and usage.

Where this model is deliberately rough

Real battery degradation is not additive and not linear — it follows a curve that drops quickly at first, flattens for years, then steepens again late in life, and it responds to how the pack was actually used rather than to tidy per-year averages. This calculator flattens all of that into four straight-line terms you add together. That trade keeps it easy to reason about, but you should know exactly what it glosses over:

• The rates are averages, not your car. The 2.5% per year, 0.5% per 10,000 miles, and 0.005% per cycle figures sit in the middle of published fleet data. A gently used Tesla or a well-managed Hyundai can beat them handily; an early air-cooled Leaf in a hot state will do worse.
• Miles and cycles overlap. Both are really counting charge-and-discharge, so this model double-counts that stress a little on purpose. If you only have solid data for one of them, feel free to leave the other at a modest value rather than inflating both.
• Chemistry is ignored. LFP packs tolerate frequent 100% charges and thousands of cycles; nickel-rich NMC/NCA cells prefer a 20–80% window. The same numbers entered here treat them identically, which they are not.
• Climate is a single dial. A 0–2 slider can't tell a garaged car with active liquid cooling from one that bakes in a parking lot and fast-charges at noon. Heat and heavy DC fast charging both matter more than this one factor can express.
• The 30% cap is a guardrail, not a prediction. It stops absurd outputs when you enter extreme values, but a genuinely worn-out or abused pack can fall past 30% — the cap will quietly understate that case.

So treat the number as a ballpark to set expectations, not a verdict. Before you spend real money on a used EV, file a warranty claim, or decide on a pack replacement, back it up with your car's onboard battery-health readout, a manufacturer diagnostic report, or a proper test from a service center. Nothing here is financial, legal, or engineering advice.