EV Battery Health Calculator

Calculate your electric vehicle battery state of health (SOH) and range degradation

Battery Information

Enter what you know - we'll calculate the rest

Selecting a model will auto-fill battery capacity and range

Battery Health Tips

  • Avoid charging to 100% daily - keep it between 20-80% for regular use
  • Minimize fast charging frequency - use Level 2 charging when possible
  • Park in shade or garage - extreme temperatures accelerate degradation
  • Precondition battery before charging in cold weather
  • Avoid leaving battery at very low or very high charge levels for extended periods

Frequently Asked Questions

What is State of Health (SOH)?

SOH represents your battery's current maximum capacity compared to its original capacity when new, expressed as a percentage.

What's a normal degradation rate?

Most EV batteries degrade 1-3% per year. Higher rates may indicate aggressive use or environmental factors.

When should I replace my battery?

Consider replacement when SOH drops below 70-80%, though many EVs remain functional below this threshold.

How accurate is this calculator?

This provides estimates based on your inputs. For precise measurements, consult your dealer's diagnostic tools.

Optimize Your Charging Strategy

With your battery health results, use our charging calculator to plan efficient charging sessions and maximize battery life.

Try Charging Calculator

Calculate Your EV Savings

Based on your battery health, calculate how much money you'll save with your EV compared to a gas car over the years.

Calculate Savings

Common EV Battery Capacities

Quick reference for popular models

Tesla

  • Model Y Long Range: 75-82 kWh
  • Model 3 Long Range: 75-82 kWh
  • Model S Long Range: 95-100 kWh
  • Model X Long Range: 95-100 kWh

Other Brands

  • BMW i4: 81.5 kWh
  • Ford Mustang Mach-E: 68-91 kWh
  • VW ID.4: 77-82 kWh
  • Hyundai Ioniq 5: 58-77 kWh
  • Kia EV6: 58-77 kWh
  • Porsche Taycan: 71-93 kWh

How We Calculate

Understanding the formulas behind our calculations

State of Health (SOH)

Direct method (if current capacity known):

SOH = (Current Capacity ÷ Original Capacity) × 100

Range-based estimation (non-linear):

SOH uses stepped calculation based on range ratio

Range degrades faster than capacity due to increased internal resistance. We use a non-linear model: minimal loss (>95% range) = close SOH match, moderate loss (85-95%) = 1.5x amplified, significant loss (<85%) = accelerated degradation.

Annual Degradation Rate

Annual Degradation = (100 - SOH) ÷ Battery Age

We apply non-linear projections: 2.5%/year for new batteries (>95% SOH), 1.8%/year for mid-life (85-95%), and higher rates for older batteries.

Charge Cycles Estimation

If not provided, we estimate:

Usable Capacity = Original Capacity × Buffer (95% Tesla, 93% others)Range per Cycle = Efficiency (km/kWh) × Usable CapacityTotal Cycles = Total Distance ÷ Range per Cycle

Most users charge 20-80% (60% depth), so actual charge events are higher than full cycles.

Note: These calculations provide estimates based on typical battery behavior. Actual results vary based on charging habits, climate, and driving patterns.