EV Usable Battery Capacity Measurement

Method and units

Estimated usable capacity = measured energy delivered to the pack ÷ (SOC increase ÷ 100). If measuring wall energy, first divide by your measured charging efficiency to estimate pack-side energy. Estimated range = usable capacity ÷ entered consumption × 100.

Worked example

If 36 kWh reached the pack while SOC rose from 20% to 80%, estimated usable capacity is 36 ÷ 0.60 = 60 kWh. At 18 kWh/100 km, the equivalent full-window energy corresponds to 333.3 km.

Supported inputs and interpretation

Energy 0.1–300 kWh; SOC 0–100% with end above start; consumption 1–100 kWh/100 km. Results are rounded for display only; internal calculations retain full JavaScript precision. Entered measurements and assumptions determine the answer.

References and limitations

The equations here use the stated unit conversions and geometric or accounting relationships; no empirical vehicle limits or manufacturer presets are supplied.

Use pack-side energy or a measured efficiency estimate; wall-meter energy includes charging losses. SOC display rounding, balancing and temperature affect the estimate. This is not a battery-health diagnosis or warranty test.

Related calculators

• Ev Charging Cost Calculator
• Ev Trip Charging Stop Planner

This planner performs the stated arithmetic; it is not a vehicle inspection, engineering approval, manufacturer's recommendation or professional review.