"Up to 75 miles" is the most common phrase on e-bike listings, and the one that disappoints most. Advertised range is measured in ideal conditions; real e-bike range depends on your weight, the hills, the wind and the assist level. The good news is you can estimate it surprisingly well with one simple sum.
This guide shows you how to work out the watt-hours of any battery, what consumption per mile is realistic, and how far real bikes sold on Amazon UK are likely to go.
The formula: watt-hours = volts × amp-hours
A battery's real capacity is measured in watt-hours (Wh). If the listing only gives volts (V) and amp-hours (Ah), multiply them:
Wh = V × Ah. For example, 48 V × 13.5 Ah = 648 Wh; 36 V × 13 Ah = 468 Wh.
Comparing amp-hours alone is misleading: a 36 V 18 Ah battery (648 Wh) holds exactly the same energy as a 48 V 13.5 Ah one (648 Wh). Always compare in Wh.
How much energy an e-bike uses per mile
Consumption is measured in Wh per mile (or per km). As a rough guide:
- 13-19 Wh/mile (8-12 Wh/km): flat roads, low assist, light rider, narrow tyres.
- 19-29 Wh/mile (12-18 Wh/km): town riding with junctions and the odd hill, medium assist.
- 29-40+ Wh/mile (18-25+ Wh/km): off-road, fat tyres, high assist, headwinds or heavy loads.
Then: range in miles ≈ battery Wh ÷ Wh per mile. A 768 Wh battery at 24 Wh/mile gives about 32 miles (51 km). Knock off 10-15% as a margin: nobody runs a battery to the last watt, and capacity falls with age.
The best number is your own. After a few weeks, note how many miles you get from a full charge on your usual route and assist level, and divide the battery Wh by that figure. That's your personal Wh per mile.
Realistic range of popular e-bikes
| Model | Battery | Wh | Realistic range* |
|---|---|---|---|
| ADO Air 20 | 37 V · 10 Ah | 370 | 12-23 miles (20-37 km) |
| EMotorad T-Rex Air / HillMiles MileCity 1 | 36 V · 13 Ah | 468 | 16-29 miles (26-47 km) |
| Fafrees Hailong One | 36 V · 13.5 Ah | 486 | 17-30 miles (27-49 km) |
| Fafrees F20 Light | 36 V · 14.5 Ah | 522 | 18-32 miles (29-52 km) |
| ENGWE EP-2 3.0 Boost | 48 V · 13.5 Ah | 648 | 22-40 miles (35-65 km) |
| ENGWE Engine Pro 3.0 Boost | 48 V · 15 Ah | 720 | 25-45 miles (40-72 km) |
| HITWAY 28" | 768 Wh | 768 | 26-48 miles (42-77 km) |
*Our own estimate using 16-29 Wh/mile (10-18 Wh/km) for mixed urban riding at medium assist, rounded. It is not a manufacturer figure; off-road or in the highest assist mode it will be lower. Fat-tyre models will usually land in the lower half of their range.
Example bikes by battery size
1. HITWAY 28" e-bike
Who it's for: commuters who want to charge once or twice a week.
- 28" (700c) step-through trekking/commuter frame
- Removable 768 Wh battery; 43-75 miles (70-120 km) claimed
- 250 W motor, 35 Nm
- Hydraulic disc brakes, 7 speeds
- 3 assist levels capped at 15, 20 and 25 km/h (about 9.3, 12.4 and 15.5 mph)
- LCD display, app and NFC unlocking
- Big battery with 28" wheels, which use less energy per mile than fat tyres
- Hydraulic disc brakes
- 35 Nm on steep hills means you work harder and use more battery there
2. ENGWE EP-2 3.0 Boost
Who it's for: riders who need strong hill assistance and fast charging.
- Folding frame, 20" fat tyres
- 48 V 13.5 Ah battery (648 Wh)
- 250 W motor, 75 Nm, torque sensor; assistance to 15.5 mph (25 km/h)
- No throttle: ENGWE states it complies with UK road rules
- Hydraulic disc brakes, 7 speeds, front and rear lights, app
- 4 A charger: full charge in about 3.5 hours (manufacturer figure)
- Torque sensor helps efficiency
- Full charge in about 3.5 hours with the 4 A charger
- Fat tyres raise consumption on tarmac
3. Fafrees F20 Light
Who it's for: short commutes and budget buyers.
- Folding 20" step-through frame
- Removable 36 V 14.5 Ah battery (522 Wh)
- 250 W motor, 35 Nm, assistance to 15.5 mph
- 7-speed gears
- Mechanical disc brakes front and rear
- StVZO-rated LED headlight and brake light
- Removable battery charges indoors
- Light, efficient 20" tyres
- 35 Nm: more battery used on hills
4. EMotorad T-Rex Air
Who it's for: mid-length mountain bike rides.
- 29" hardtail with 29 x 2.1" tyres
- 250 W rear hub motor, 40+ Nm, 5 assist levels
- 36 V 13 Ah battery (468 Wh); up to 40 miles claimed
- 100 mm suspension fork
- Hydraulic disc brakes, Shimano 7-speed
- Metal mudguards, front light with horn; 5-year frame and 2-year battery warranty
- Removable battery, about 80% charge in 4.6 hours claimed
- 29" wheels roll efficiently on tracks
- Off-road, range drops quickly
Worked example: a hilly commute
Say you ride 8 miles (13 km) each way into Leeds, with a couple of steady climbs, at medium assist, and weigh 85 kg. That's 16 miles a day. Hills and stop-start traffic put you near the top of the urban band, so use 26 Wh per mile: 16 × 26 = 416 Wh a day. Add 15% for winter and battery ageing and you need about 480 Wh per day of riding.
A 468-486 Wh battery would cover one day per charge, and nothing more, which leaves no margin for a detour or a cold snap. A 648 Wh battery gives a comfortable day with spare, and a 768 Wh battery would stretch to roughly a day and a half. If you can charge at work, the smaller pack is fine; if you can only charge at home every other night, size up.
What eats your range
- Assist level: the single biggest factor. Going from eco to turbo can double consumption.
- Hills: climbing takes a lot of energy, and coming down gives almost none back (e-bikes don't regenerate like cars).
- Total weight: rider, bag and bike. A 30 kg fat bike uses more than a 22 kg commuter.
- Tyres and pressure: wide or under-inflated tyres increase rolling resistance.
- Stop-start riding: every set of lights is a spike in consumption. Pull away in a low gear.
- Cold: below about 5-10 °C the battery delivers less, temporarily. A January commute can lose a noticeable chunk of range.
- Wind: a headwind on an exposed road pushes consumption up fast.
How to make the battery last longer
Lithium batteries lose capacity with charge cycles and with age. To slow that down:
- Avoid leaving it at 0% or 100% for days; store it at 40-70%.
- Charge at room temperature, not straight in from a frosty shed or a hot car.
- Use the original charger. Fast chargers are convenient, but you don't need them daily.
- In winter, keep the battery indoors.
- Ride in a sensible gear: spinning at a steady cadence lets the motor work efficiently, while grinding a big gear at low speed wastes energy and heats the motor.
- Keep tyres at the right pressure and the chain clean; both reduce drag on every single mile.
A well-kept battery typically keeps most of its capacity for several years of regular commuting. When range drops noticeably on the same route and weather, it may be time to have the battery tested by a bike shop before buying a replacement.
If you're shopping, work out your weekly mileage first, then choose the battery. Our commuter e-bike and folding e-bike guides list models by use.
See long-range e-bikes on Amazon →
Frequently asked questions
How do I calculate the Wh of an e-bike battery?
Multiply the voltage by the amp-hours: Wh = V x Ah. For example, 48 V x 15 Ah = 720 Wh.
Why doesn't my e-bike reach its advertised range?
Manufacturers usually measure range in the lowest assist mode, on flat ground, with a light rider and in mild weather. With medium assist, hills and British weather, half the claimed figure or a little more is typical.
Is a 36 V or 48 V battery better?
At the same Wh they store the same energy. 48 V systems often feel punchier when pulling away and climbing, but range is decided by watt-hours, not voltage.
How many miles is 500 Wh on an e-bike?
Roughly 17-30 miles (27-48 km) in mixed riding at medium assist, depending on hills, rider weight, tyres and temperature. Flat riding in eco mode can go further.
Does an e-bike battery recharge going downhill?
On almost all e-bikes, no. Very few models have regenerative braking, and where they do the energy recovered is small.
How long does an e-bike battery last?
It depends on use and care; capacity fades gradually with charge cycles and age. Avoiding unnecessary full charges, deep discharges and temperature extremes helps it last longer.