Tech & Energy
EV Range Calculator
The EPA range number on an EV's window sticker ("300 miles!") is a controlled lab cycle that averages 48 mph with the HVAC off. Real-world highway driving at 75 mph with the heat on at 20°F drops that to about 180 miles — a 40% range hit. If you're planning a road trip, you need to know the actual range under actual conditions, not the marketing number. This calculator factors in average speed, ambient temperature, and current state of charge to give you a realistic range estimate. Use it before the road trip to plan charging stops that actually work.
Real range (mi)
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- Speed factor
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- Temp factor
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- Highway %
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The two big range killers: speed and temperature
Speed matters because air drag rises with the square of velocity. Going 70 mph instead of 55 mph nearly doubles aerodynamic drag and cuts range 15-25%. Going 80 mph instead of 70 mph cuts another 10-15%. Highway road trips are where EV range falls apart relative to EPA.
Cold hurts in two ways: (1) battery chemistry is less efficient at cold temps (less usable capacity), (2) cabin heating draws significant battery (heaters use 1-3 kW continuously). Below 32°F, you lose 20-30% range; below 0°F, 30-40%.
Heat hurts less but still hurts. AC pulls 1-2 kW continuously — about 5-10% range hit in hot weather. Battery thermal management also adds load at high ambient temps above 100°F.
Worked example: a Tesla Model 3 with 300-mile EPA range, on a road trip at 75 mph in 30°F weather. Speed factor ~0.85, temp factor ~0.75. Real range = 300 × 0.85 × 0.75 = 191 miles. Plan charging stops accordingly.
Other range factors
- Cargo / passengers: every 100 lb extra reduces range ~1-2%. A car loaded with 4 adults + luggage drops 5-8% from a solo-driver baseline.
- Roof rack / cargo carrier: aero hit is huge — 10-20% range loss at highway speed. EVs are sensitive to drag in a way ICE cars aren't.
- Towing: cuts range 30-60% depending on trailer size and shape. Heavily impacts EV trip planning.
- Hilly terrain: net range similar to flat (you regen on downhills), but real-time consumption looks scary climbing.
- Headwind: a 20 mph headwind on flat ground cuts range like driving 20 mph faster.
- Battery age: most EV batteries lose 5-10% capacity in the first 100K miles, plateau after that. 5-year-old battery at 90% original capacity loses 10% range vs new.
How to use this calculator
- EPA range: from the car's window sticker or manufacturer spec.
- Average speed: city, suburban, or highway speed.
- Temperature: ambient temp in °F. Default 70°F is ideal.
- Battery SOC start %: current state of charge (100 = full, 80 = 80%).
- Output: real estimated range, speed factor, temp factor, % of EPA you're actually getting.
- For trip planning, target 10-15% buffer below the calculated range — conditions vary, and arriving at a charger with 0% leaves zero margin.
Common scenarios
300-mile EPA Tesla on a 350-mile road trip in summer at 75 mph. Speed factor 0.87, temp factor 0.95. Real range from 100% = ~248 miles. Need one Supercharger stop, ideally around 200 miles in to leave buffer.
250-mile EPA Ford Mach-E winter commute, 25°F, 65 mph average, 80% SOC. Speed factor 0.93, temp factor 0.80. Real range from 80% = 250 × 0.93 × 0.80 × 0.80 = 149 miles. Plenty for a 50-mile round-trip commute.
200-mile EPA Chevy Bolt, summer city driving at 35 mph, 70°F. Speed factor 1.20 (slow is efficient), temp factor 1.00. Real range = 240 miles. City driving exceeds EPA because the regen recovery is significant in stop-and-go.