kWh to Miles Converter
An electric car has a 70 kWh battery, but how far it goes depends on a second number that most buyers never check: how many miles each kilowatt hour buys.
Quick answer: multiply the kWh by your efficiency in miles per kWh. At a typical 3.5 mi/kWh, 70 kWh gives about 245 miles, 40 kWh gives 140 miles and 10 kWh gives 35 miles.
The kWh to miles formula
Miles equal the energy in kWh times the efficiency in miles per kWh. Efficiency is miles driven divided by kWh used (Motorway: Miles per kWh explained).
Use the usable battery capacity rather than the gross figure, because part of the battery is held in reserve.
For 70 kWh at 3.5 mi/kWh, 70 × 3.5 is 245 mi.
For 22 kWh used over 80 miles, 80 ÷ 22 is 3.6 mi/kWh.
Miles per kWh and electric cars
Miles per kWh is the electric car equivalent of miles per gallon. Above 3.5 is good for most cars in real conditions, 2.5 to 3.4 is average and below 2.5 is poor (Motorway: Miles per kWh explained).
Small city cars may reach 4 to 5.5 mi/kWh, family hatchbacks 3.5 to 4.5, mid-size SUVs 2.8 to 3.5 and performance cars 2 to 3.
Official WLTP figures are often 10 to 20 percent higher than what drivers see in daily use.
How to convert kWh to miles step by step
- Find the usable battery capacity in kWh.
- Find your car efficiency in miles per kWh.
- Multiply the two to get the range in miles.
- Reduce by 20 to 40 percent for very cold weather.
Example 1: a 70 kWh car at 3.5 mi/kWh
- Start with 70 kWh.
- 70 × 3.5 = 245.
- The range is about 245 miles.
70 kWh = 245 mi
Example 2: 15 kWh added at 4 mi/kWh
- Start with 15 kWh.
- 15 × 4 = 60.
- The charge adds about 60 miles.
15 kWh = 60 mi
Example 3: working out efficiency
- Start with 80 miles on 22 kWh.
- 80 ÷ 22 = 3.6.
- The efficiency is 3.6 mi/kWh.
80 mi on 22 kWh = 3.6 mi/kWh
The answer is only as good as the efficiency figure, so use your own recent driving data if you have it.
kWh to miles conversion table
| Energy | At 2.5 mi/kWh | At 3.5 mi/kWh | At 4.5 mi/kWh |
|---|---|---|---|
| 10 kWh | 25 mi | 35 mi | 45 mi |
| 20 kWh | 50 mi | 70 mi | 90 mi |
| 30 kWh | 75 mi | 105 mi | 135 mi |
| 40 kWh | 100 mi | 140 mi | 180 mi |
| 50 kWh | 125 mi | 175 mi | 225 mi |
| 60 kWh | 150 mi | 210 mi | 270 mi |
| 70 kWh | 175 mi | 245 mi | 315 mi |
| 80 kWh | 200 mi | 280 mi | 360 mi |
| 100 kWh | 250 mi | 350 mi | 450 mi |
The highlighted row is 70 kWh, a common battery size. Read across to see how efficiency changes the range.
A quick mental shortcut for kWh to miles
Multiply by 3.5 for a typical car, so 40 kWh is about 140 miles. Use 4 for an efficient hatchback and 3 for a large SUV.
For a quick cold weather check, reduce the answer by about a quarter.
Factors that change efficiency
Speed has a big effect, because drag rises sharply above 60 mph. Cold weather, cabin heating, under-inflated tyres, heavy loads and hills all lower miles per kWh (Motorway: Miles per kWh explained).
Below 5 degrees Celsius, real-world range can fall by 20 to 40 percent.
Cost per 100 miles
Divide 100 by your miles per kWh to get the energy needed, then multiply by the electricity price. At 4 mi/kWh that is 25 kWh, and at a price of 0.28 per kWh the cost is 7.00.
At 3 mi/kWh the same distance costs about 9.33.
Usable versus gross battery capacity
Car makers quote gross capacity, but only the usable part drives the wheels. A 64 kWh pack might offer 60 kWh usable, which is the number to multiply.
Always check the usable figure in the specification sheet.
Checking your answer
Divide the miles by the kWh to recover the efficiency. If 245 ÷ 70 gives 3.5, the conversion is right.
Compare against the official range and expect real-world figures to be lower.
Charging losses
Charging from the wall loses some energy as heat. With a 10 percent loss, 50 kWh at the battery needs about 55.556 kWh from the wall.
So the wall energy is a little higher than the battery energy.
Cold weather
Cold weather and cabin heating raise energy use, so the miles per kWh figure falls. At 3 mi/kWh, 10 kWh gives 30 miles, while at 4 mi/kWh it gives 40 miles.
Quick conversion answers
| Conversion | Result |
|---|---|
| 10 kWh to miles | 35 mi at 3.5 mi/kWh |
| 20 kWh to miles | 70 mi at 3.5 mi/kWh |
| 40 kWh to miles | 140 mi at 3.5 mi/kWh |
| 60 kWh to miles | 210 mi at 3.5 mi/kWh |
| 70 kWh to miles | 245 mi at 3.5 mi/kWh |
| 100 kWh to miles | 350 mi at 3.5 mi/kWh |
Where this conversion is used
Electric car owners estimate range and charging needs.
Buyers compare efficiency between models.
Fleet managers and analysts plan routes and energy costs.
Common mistakes to avoid
- Using gross battery capacity. Use the usable kWh.
- Trusting official range only. Real-world range is often lower.
- Ignoring weather and speed. Cold and motorway driving cost miles.
- Mixing km and miles. Keep one unit throughout.
Related converters
Frequently asked questions
How many miles per kWh is good?
Above 3.5 miles per kWh is good for most cars in real conditions.
How far can 70 kWh go?
About 245 miles at 3.5 mi/kWh.
How do I calculate miles per kWh?
Divide the miles driven by the kWh used.
Why is real range lower than official range?
Cold weather, speed, heating and loads all use more energy than the lab test.
How many miles does 1 kWh give?
About 3 to 4 miles for most electric cars.
How do I find the cost per 100 miles?
Divide 100 by the miles per kWh and multiply by the price per kWh.
Sources
- Motorway: Miles per kWh explained (motorway.co.uk)
