Calculate SimplyHow to use
Start with the worked example to understand the inputs, then replace every relevant value with your own figures. Use one currency and consistent units throughout. Add or remove rows where offered; irrelevant conditional fields are disabled and excluded. Select Calculate after editing. Review negative values and any “not determined” result rather than assuming every scenario must be profitable. Download a text summary or print the page for your records.
Formula and assumptions
Choose metric units for km, liters per 100 km and battery kWh per 100 km. US mode uses miles, miles per US gallon and miles per battery kWh. Changing the mode changes interpretation and resets efficiency examples; it does not convert your entered distance. Charging efficiency increases grid energy above battery energy. Home and public charging shares create a weighted electricity price. Annual savings are 12 times the monthly operating difference. Charger payback excludes vehicle purchase prices, financing, insurance and maintenance. If savings are not positive, no payback is reported.
metric: fuel = distance × L/100km / 100; EV battery kWh = distance × kWh/100km / 100; grid kWh = battery kWh / efficiency. US: distance / MPG and distance / mi/kWh.
Worked example
Example only: replace rates with your own figures.
Inputs
- Distance and fuel units: metric
- Distance per driving day: 40
- Driving days per month: 22
- Gas vehicle efficiency: 8
- EV efficiency: 18
- Fuel price per liter or US gallon: 1.5
- Home electricity rate per kWh: 0.2
- Public charging rate per kWh: 0.5
- Home charging share: 80 %
- Charging efficiency: 90 %
- Home charger installation cost: 1000
- Monthly gas cost: 105.6 USD
- Monthly EV cost: 45.76 USD
- Annual operating savings: 718.08 USD
- Charger payback: 1.3926 years
- Grid electricity per month: 176 kWh
Frequently asked questions
Are the example rates current market prices?
No. Example inputs demonstrate arithmetic, not live prices, tax rules, salary surveys or sponsor benchmarks. Enter a dated quote, bill, manufacturer specification or verified fee schedule that applies to your situation. Compare a conservative and an optimistic scenario separately.
Why is a result not determined?
Some calculations have no meaningful value when a denominator is zero, savings are non-positive, a target cannot be reached or your data do not bracket an intersection. The tool leaves that result undetermined instead of displaying infinity or inventing a recommendation. Check the method and your inputs.
Sources
Sources explain the underlying concepts, not an endorsement of this website or its results. Method review: 20 October 2026.