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E-bike range explained: what really affects it

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In short

E-bike range is the battery's capacity in watt-hours divided by how many Wh your riding uses per mile. Gentle riding on flat roads in a low assist mode might use around 10 to 15 Wh per mile; hills, a heavier load, high assist, headwinds and cold can push it past 20. So a 500 Wh battery might give anything from roughly 25 to 50 miles.

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Maker range figures are useful for comparing bikes, but they rarely match what you see on your own commute. That is not necessarily because the claim is wrong. Range depends on how hard the motor has to work, and that changes with every hill, gust of wind and change of assist level. This guide explains the factors in plain terms and shows a simple way to estimate your own range from your battery size, so you can choose a battery that suits your journeys.

The simple formula: Wh divided by Wh per mile

A battery's capacity in watt-hours (Wh) is its volts multiplied by its amp hours. A 36 V 14 Ah pack holds about 504 Wh. Divide that by how much energy your riding uses per mile and you get an estimate of range.

At 15 Wh per mile, 504 Wh gives about 34 miles (around 54 km). At 20 Wh per mile, it gives about 25 miles. The battery size and charge cost tool lets you change the numbers to match your bike.

  1. Battery size36 V x 14 Ah= 504 Wh
  2. Range (54 km)504 Wh ÷ 15 Wh/mile≈ 34 miles
  3. Cost per full charge504 ÷ 1,000 x 25p= 12.6p
Volts x amp-hours gives watt-hours; divide by your Wh per mile for range. Worked at 25p per kWh and 15 Wh per mile.

What changes your Wh per mile

Each factor below changes how hard the motor works, and so how quickly it uses the battery.

FactorEffect on range
Assist levelHigher modes use much more energy; the biggest single control you have
HillsClimbing takes a lot of energy, especially from a standing start
Rider and load weightMore weight means more energy for hills and acceleration
Speed and windAir resistance rises fast with speed and headwinds
Tyre type and pressureSoft or knobbly tyres roll less easily than firm, smooth ones
TemperatureCold batteries deliver less usable energy until they warm up
Stop-start ridingPulling away repeatedly uses more energy than steady cruising
Range factors

Why maker range claims differ from yours

Range claims are usually given as "up to" a figure, often measured in a low assist mode, on mostly flat ground, in mild weather and with a lighter rider. Your journey may include hills, traffic lights and winter mornings.

A practical approach is to take the maker's figure as a best case and plan for perhaps two-thirds of it in mixed riding, then check your own results over a few weeks. Your display may also show a remaining range estimate, which is based on how you have been riding recently.

Measuring your own Wh per mile

The most reliable range figure is your own. Start a ride with a fully charged battery and note the distance on your display or a cycle computer. Ride your usual routes in your usual assist level until the battery is low, then divide the battery's Wh by the miles you covered. If you used 500 Wh over 30 miles, your figure is about 17 Wh per mile.

Repeat this in summer and winter, and on hilly and flat routes, and you will have a realistic range for each kind of ride. Remember that as the battery ages its usable Wh falls, so the same test a few years later will show fewer miles. That is normal and is covered in our guide to how long an e-bike battery lasts.

How to get more range

You do not need to change bikes to ride further. Small changes add up.

  • Use the lowest assist level that feels comfortable, and save the highest for steep hills.
  • Change down a gear before stopping so you set off in a low gear.
  • Keep tyres at the pressure shown on the sidewall.
  • Keep the chain clean and lubricated.
  • Carry only what you need, and use a rack rather than a heavy rucksack if that suits you.
  • In winter, keep the battery indoors and fit it just before you ride.

How to ride an e-bike efficiently →

Choosing a battery for your journeys

Work out your longest regular ride, multiply it by a cautious Wh per mile figure such as 20, and add some margin for battery ageing and cold weather. If the result is well under your battery's Wh, you will rarely run short. If it is close, consider a bigger battery or charging at both ends of your journey.

Our guide to what size e-bike battery you need goes through this in more detail, and our long-range e-bike guide covers bikes with larger packs.

Frequently asked questions

Does a higher voltage battery give more range? Not by itself. Range follows total Wh. A 48 V 10 Ah pack (480 Wh) holds slightly less energy than a 36 V 14 Ah pack (504 Wh).

Why does my range drop in winter? Cold slows the chemical reactions in lithium-ion cells, so less energy is available until they warm up. Range usually recovers in milder weather.

Is electric mountain bike range lower? Often, per mile, because off-road climbs, soft ground and knobbly tyres use more energy. Riders often think in terms of climbing rather than distance.

Does range fall as the battery ages? Yes. As capacity fades, the same riding gives fewer miles. Most packs lose capacity gradually over years.

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