How to use this calculator
Enter the usable capacity of your battery, not its gross pack capacity, and the current displayed state of charge. Choose the charge percentage you want to leave unused. Enter a battery-side efficiency representative of the planned drive. The calculator estimates energy between those two charge levels and divides it by driving consumption. Try a less efficient value to see how your plan changes.
This is a constant-consumption estimate using an approximately linear relationship between displayed charge and usable energy. It is not an EPA rating, route planner or guarantee of reaching a charger. Weather, speed, heating, load, battery condition and route elevation can change consumption. The chosen reserve is an input assumption, not a manufacturer recommendation.
The formula
A worked example
A usable 60 kWh battery at 80% charge, with a 10% reserve, supplies 42 kWh in this model. At 3.5 mi/kWh, estimated range is 147 miles (236.57 km). At 20 kWh/100 km instead, the same energy gives 210 km. These are different efficiency scenarios, not equivalent unit values.
Efficiency sensitivity
For 42 kWh above the chosen reserve; these are illustrative inputs.
| Battery-side mi/kWh | Estimated miles |
|---|---|
| 3.0 | 126 |
| 3.5 | 147 |
| 4.0 | 168 |
Common questions
Should I use gross or usable battery capacity?
Use the current usable capacity associated with the displayed charge range. Gross capacity can include protected energy buffers that are not available for driving. If only the gross figure is known, do not treat the result as a dependable route estimate.
Why not use the kWh shown on a charging receipt?
Energy delivered by a charger can include charging losses. This model starts with stored usable battery energy, so it needs battery-side driving consumption. Mixing wall energy per distance with stored capacity uses inconsistent measurement boundaries.
What if reserve equals the current charge?
The estimated energy and range above reserve are zero. Reserve greater than current charge is rejected rather than producing a negative range.
Can I include regenerative braking?
Use measured net battery consumption from comparable driving, which can already reflect recovered energy. Do not add a separate regeneration allowance to that value.
Why does my dashboard give a different range?
Your vehicle may account for recent driving, temperature and battery estimates in ways this simple model does not. Use its guidance and current route conditions when planning charging stops.
Sources & calculation method
U.S. DOE Alternative Fuels Data Center: All-Electric Vehicles describes stored battery energy and factors affecting range, including temperature, speed, load and inclines. The energy-divided-by-consumption equation and linear state-of-charge assumption above are the model used by this calculator; the source does not supply a rating for your entered vehicle.
References accessed September 12, 2026. Sources support the stated context, not an endorsement or independent review of AutomotiveCalc.
Formula examples and input validation have automated checks. This page has not received an independent automotive professional review. Read our review standards.