What this tool does
This tool converts electric vehicle energy consumption from kilowatt-hours per 100 miles (kWh/100 mi) to kilometers per kilowatt-hour (km/kWh). These are two fundamentally different ways of expressing EV efficiency. The kWh/100 mi metric, commonly used in the United States by the EPA, measures how much energy a vehicle consumes over a fixed distance. The km/kWh metric, widely used in Europe and other metric-system countries, measures how far a vehicle can travel on a fixed amount of energy. By converting between these units, drivers, manufacturers, and analysts can compare EV efficiency ratings across regions without confusion. The tool also provides related metrics including miles per kWh, kWh per 100 km, MPGe equivalents, and Wh/km, giving you a complete picture of an electric vehicle's energy efficiency. Quick presets for popular EV models let you instantly see how well-known vehicles perform in km/kWh terms.
How it works
The conversion relies on the exact relationship between miles and kilometers. Since 1 mile equals exactly 1.609344 kilometers, 100 miles equals 160.9344 kilometers. The core formula is:
km/kWh = 160.9344 / kWh per 100 miles
This can be derived step by step. First, calculate miles per kWh by dividing 100 miles by the energy consumed: miles_per_kwh = 100 / kWh_per_100_miles. Then convert from miles to kilometers: km_per_kwh = miles_per_kwh * 1.609344. Combining these gives: km_per_kwh = (100 / kWh_per_100_miles) * 1.609344 = 160.9344 / kWh_per_100_miles.
For additional metrics, the tool calculates kWh/100 km by dividing the input by 1.609344, since 100 km is shorter than 100 miles. MPGe is derived from the EPA standard where 33.705 kWh equals the energy content of one gallon of gasoline, so MPGe = miles_per_kwh * 33.705. Watt-hours per kilometer is simply 1000 divided by km/kWh.
Who should use this
1. EV owners in metric-system countries who want to interpret EPA-rated kWh/100 mi figures in the more familiar km/kWh format used locally. 2. Car buyers comparing electric vehicles sold across different markets, where efficiency is stated in different units on spec sheets. 3. Fleet managers operating electric vehicles across borders who need consistent efficiency metrics for cost analysis and route planning. 4. Automotive journalists and reviewers translating American EV test results for international audiences. 5. Environmental researchers comparing transportation energy efficiency data from US and European sources. 6. EV charging network planners estimating how far vehicles can travel per unit of energy consumed at their stations.
Worked examples
Example 1: A Tesla Model 3 rated at 25.5 kWh/100 miles. km/kWh = 160.9344 / 25.5 = 6.31 km/kWh. This means the Model 3 travels about 6.31 kilometers on each kilowatt-hour of energy. That translates to roughly 3.92 mi/kWh, an MPGe of 132.2, and 158.5 Wh/km.
Example 2: A Rivian R1T rated at 48.2 kWh/100 miles. km/kWh = 160.9344 / 48.2 = 3.34 km/kWh. The larger, heavier truck achieves 3.34 km/kWh, reflecting its higher energy consumption. This equates to about 2.07 mi/kWh, an MPGe of 69.9, and 299.4 Wh/km. With a 75 kWh battery, the estimated range would be approximately 250 km.
Example 3: A Hyundai Ioniq 6 rated at 24.1 kWh/100 miles. km/kWh = 160.9344 / 24.1 = 6.68 km/kWh. Among the most efficient EVs available, the Ioniq 6 achieves 6.68 km/kWh. Its aerodynamic design helps it reach an MPGe of 139.8 and consume only 149.7 Wh/km.
Limitations
1. EPA ratings are measured under standardized test conditions that may not reflect real-world driving. Actual km/kWh performance varies with speed, temperature, terrain, cargo, and driving style. 2. The converter assumes the input kWh/100 mi value is accurate. Manufacturer-stated figures and real-world measurements can differ significantly, sometimes by 20 percent or more. 3. Cold weather can reduce EV efficiency by 30 to 40 percent due to battery heating and cabin climate control, making converted values optimistic in winter conditions. 4. Highway driving at sustained high speeds typically reduces km/kWh compared to city driving, where regenerative braking recaptures energy. 5. The tool does not account for charging losses, which typically add 10 to 15 percent to the energy drawn from the grid compared to what reaches the battery. 6. EV presets reflect approximate EPA-rated values and may not match specific trim levels, wheel sizes, or model year variations.
FAQs
Q: Why is km/kWh used instead of kWh/100 km in many countries? A: The km/kWh metric is intuitive because higher numbers mean better efficiency, similar to how MPG works. It directly answers the question of how far you can go on one kWh. Some countries and manufacturers prefer kWh/100 km because it parallels the familiar L/100 km fuel consumption metric. This tool provides both so you can use whichever you prefer.
Q: How does the MPGe calculation work? A: MPGe (miles per gallon equivalent) is an EPA metric that compares EV efficiency to gasoline vehicles. The EPA determined that one gallon of gasoline contains 33.705 kWh of energy. MPGe equals miles per kWh multiplied by 33.705. It provides a familiar reference point for comparing EVs to traditional vehicles, though the comparison is imperfect since it does not account for differences in energy production efficiency.
Q: Why do trucks and SUVs have much lower km/kWh values? A: Larger, heavier vehicles require more energy to move due to greater rolling resistance and aerodynamic drag. A compact sedan like the Ioniq 6 might achieve over 6.5 km/kWh, while a full-size truck like the Rivian R1T may only achieve around 3.3 km/kWh. Weight, frontal area, and tire size are the primary factors driving these differences.
Q: Can I use this converter for plug-in hybrid vehicles? A: Yes, but only for the electric-only driving portion. Plug-in hybrids have separate efficiency ratings for electric mode and gasoline mode. The kWh/100 mi figure applies only to electric driving, so the converted km/kWh value represents efficiency when running purely on battery power.
Q: How accurate is the 1.609344 conversion factor? A: The international mile is defined as exactly 1.609344 kilometers. This is not an approximation but an exact conversion factor established by international agreement in 1959. The conversion between kWh/100 mi and km/kWh using this factor is mathematically precise.
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