EV Road Trip Charging Calculator

About the EV Road Trip Charging Calculator

Plan the energy side of an electric-car trip, with no map service and nothing to install. Enter the trip as one or more legs — a distance and the speed you will hold — the outside temperature and whether the heating or air conditioning will be on, the load, the car’s consumption at a speed you know, its battery and the power of the fast chargers on your route. The page adjusts the consumption for each leg’s speed (air drag grows with the square of the speed), for extra load and for the weather, using the effects fueleconomy.gov and AAA report from tests of electric cars in the cold and the heat.

Then it plans the charging: drive until the charge reaches the buffer you want to keep, charge to your level, and so on — the last stop charging only what the rest of the trip needs. You get the number of stops, the charge-to level and the minutes at each, the driving and charging time, the total trip time and the energy cost at your home and fast-charging prices, and a comparison that shows how driving slower or charging only to 80% changes the trip. It does not know where chargers are or whether they are available right now: the stops are placed where the charge runs low. Without a pass, the free preview shows the total trip time in full with the first rows of the stops and of the comparison; a Pro pass unlocks every figure, the summary and the CSV.

Common uses

• Deciding before a holiday how many charging stops to plan and where they roughly fall.
• Seeing what a cold morning or a full car does to a familiar route.
• Checking whether driving 10 km/h slower or charging only to 80% gets you there sooner.
• Working out the trip’s energy cost at home and at fast chargers.

How the consumption is adjusted

• Speed. Air drag is ½ × air density × drag coefficient × frontal area × speed² (NASA’s drag equation), with air at about 1.225 kg/m³ at sea level (NASA’s atmosphere model). The page adds — or, at a lower speed, takes away — the difference between the drag at your figure’s speed and at each leg’s speed, divided by 83%: in fueleconomy.gov’s highway breakdown of an electric car, 73 of the 88 points of energy left for driving after charging and accessory losses reach the wheels (where the energy goes).
• Load. Extra mass adds rolling resistance: the tyres’ coefficient × the mass × gravity. The coefficient comes from the EU tyre label’s class (A up to 6.5, B 6.6–7.7, C 7.8–9.0, D 9.1–10.5, E 10.6 N/kN and more; Regulation (EU) 2020/740).
• Weather. fueleconomy.gov reports AAA’s tests: at 20°F (−7 °C) instead of 75°F (24 °C) an electric car’s fuel economy drops about 39% and its range 41% with the heater on, and 8% and 12% without it (cold weather); at 95°F (35 °C) with the air conditioning on, range drops 17% (AAA). The page uses those points — consumption up by the economy loss, usable battery down by the rest of the range loss; at 95°F, where only the range loss is published, all of it counts as extra consumption — in a straight line between them, and the nearest point beyond them. Your consumption figure is taken as measured at a mild temperature.

How the stops are planned

The car leaves with your departure charge and drives until it would fall to your buffer; there it charges to your level, and so on. The last stop charges only what the rest of the trip needs (rounded up to a whole per cent), because charging is fastest when the battery is low. Each stop’s minutes come from the same model as the EV Charging Time Calculator: the lower of the charger’s and the car’s power, slowing above the taper point — and with the maker’s fast-charge time, the car’s real average speed.

Your minutes per stop for parking and plugging in are added to each stop. The energy cost counts the part of your departure charge that the trip uses at your home price (divided by the home charging efficiency) and the energy charged on the way at your fast-charging price.

Slower, or shorter stops?

Below the plan, the page works the trip out again a little slower (10 km/h or 5 mph) and charging only to 80% — or to 90% when you charge to 80% already. Driving slower saves energy at road speeds, because air drag grows with the square of the speed; whether it saves time depends on how fast the chargers are, and the comparison shows it for your trip. Charging past 80% is slow on DC, so on a long trip two short stops at 80% can beat one long one at 100%.

Limitations

• No map, no routing and no live charger availability: the stops are placed where the charge reaches your buffer — choose real chargers a little before each point.
• Hills, wind, rain and traffic are not modelled: climbing costs energy, and an electric car recovers part of it going down.
• The weather effects are averages of the electric cars AAA tested; your car may differ.
• The drag coefficient, frontal area and tyre class start as placeholders: enter your car’s for its own figures.
• An estimate for planning, not a guarantee of range.

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