EV road-trip calculator guide
What does this calculator help you figure out?
A road trip in an EV is an energy budget: how many kWh the distance needs, how many you leave with, how many you want on arrival, and how many you must add at chargers in between. Enter the trip distance, your efficiency in miles per kWh, usable battery, starting and arrival percentages, the average power you expect from fast chargers, and the price per kWh. The calculator works out driving energy, the energy shortfall you need to buy, how many stops that implies if each stop adds at most 70% of the pack (a typical 10%→80% session), the time plugged in, and the cost. Origin and destination are optional labels for the printout. Use 3.5 mi/kWh for a mid-size EV cruising at 65–70 mph in mild weather, 3.0 for a large SUV or a cold day, and 2.5 for a truck or trailer. A 50 kW average is realistic for a car with a 150 kW peak once the charging curve tapers past 60–70%.
How is the result calculated?
Driving energy (kWh) = distance (mi) ÷ efficiency (mi/kWh). Energy to add (kWh) = max(0, driving energy + battery × arrival % ÷ 100 − battery × start % ÷ 100). Stops = ceil(energy to add ÷ (0.7 × battery)). Charging time (h) = energy to add ÷ charger power (kW). Cost = energy to add × price per kWh.
Worked example
Worked example: 240 miles at 3.5 mi/kWh in a 75 kWh car leaving at 90% and aiming to arrive at 15%, using a 50 kW average and $0.16 per kWh. Driving energy = 240 ÷ 3.5 = 68.6 kWh. Energy on board at departure = 75 × 0.90 = 67.5 kWh; energy wanted on arrival = 75 × 0.15 = 11.25 kWh. Energy to add = 68.57 + 11.25 − 67.5 = 12.3 kWh. One stop covers that (12.3 ÷ 52.5 rounds up to 1), taking 12.32 ÷ 50 = 0.2 hours, about 15 minutes, and costing 12.32 × $0.16 = $1.97, the figure the calculator displays. At a typical $0.45 per kWh public fast charger the same 12.3 kWh costs about $5.54.
Units and conversion notes
Distance is in miles with a kilometre option (converted at 1.609344 km per mile). Efficiency is miles per kWh, so convert kWh/100 km with 62.137 ÷ (kWh/100 km), which makes 18 kWh/100 km about 3.45 mi/kWh, and Wh/mi with 1,000 ÷ Wh/mi. Battery is in kWh, charging power in kW as an average over the session rather than the peak on the station label, and the rate is currency per kWh. Charging time is decimal hours rounded to one place: the default 12.32 ÷ 50 = 0.246 h shows as 0.2 h but is closer to 15 minutes.
What does the result mean?
This is a modelled estimate, not a meter reading. Real consumption moves with weather, occupancy, appliance age, standing charges, and tariff structure, and equipment rarely runs at its nameplate rating. Use the figure to compare options against each other, then confirm against your own bill and the manufacturer's specification before committing to a purchase. On this page the figure rests entirely on origin, destination, trip distance, vehicle efficiency, usable battery capacity, starting charge, arrival target, average charging power, charging rate, market / jurisdiction, effective date, data source, update owner and review date, so start there if the ev road-trip calculator returns something you did not expect.
Common mistakes to avoid
Good to know: the calculator assumes the whole pack charges at the average power you enter, but real sessions slow sharply above 80%, so plan stops that end at 70–80% rather than 100%. It does not add charging losses because public chargers bill for delivered kWh; if you top up at home instead, the wall meter will show roughly 10% more than the energy to add. A single-stop result also hides a hard question: whether a charger exists near the point where you reach 10–15%. Check a live charger map, and add a 10–20% consumption penalty for headwinds, rain, roof boxes, or winter.
Energy results depend on tariffs, equipment behavior, region, weather, and installation assumptions. Verify rates and electrical decisions with the utility, manufacturer, or qualified professional.
