E-Bike Range Calculator

How to use the calculator

1. Pick your battery. The capacity in watt-hours (Wh) is printed on the battery itself or on the bike’s spec sheet. The most common are 400, 500, 545, 625, 750 and 800 Wh. If you run two batteries or a range extender, add the capacities together.
2. Pick the mode you’ll ride in most of the time. Below the result you’ll see the chart with the miles in all four modes.
3. Enter your weight, the bike’s weight and what you carry. The bike’s weight is on the manufacturer’s spec sheet. If you carry a child seat with a kid or panniers, count it under “Load.”
4. Pick the terrain and speed. The speed is the one you aim for on the flat: on climbs, the calculator lets you slow down if there isn’t enough power.
5. Set the temperature and tire. If you’re riding in winter, enter the real morning temperature.
6. Under More settings you can fine-tune the exact elevation gain of your route (feet of climbing ÷ miles), the wind and how hard you pedal.

If your bike is saved in My Bike, the calculator loads the battery and weights on its own.

How we calculate e-bike range

It’s our own model, with all the math in plain view. It doesn’t copy any manufacturer’s data; it’s inspired by the variables brands use in their range assistants (mode, weight, terrain, speed, tire, wind and temperature).

1. Energy you can actually use

Usable energy (Wh) = battery capacity × 0.9 × temperature factor

We take off 10% because the system never fully drains the cells and because a battery a few years old no longer delivers its rated capacity. The temperature factor comes from the typical capacity of the lithium cells in e-bike batteries (18650 and 21700 formats): 100% at 68 °F (20 °C), 80-85% at 32 °F (0 °C), 60-70% at 14 °F (−10 °C) and 40-50% at −4 °F (−20 °C). Between those points we interpolate.

2. What the bike needs to move

We use the same physics model as the power and speed calculator: the power needed is the sum of air resistance, tire rolling resistance and the grade, plus 2.5% for drivetrain losses. We split your ride into three parts, flat, uphill and downhill, with as much descending as climbing (an out-and-back or a loop). With 63 ft of climbing per mile (12 m/km) and 4% climbs, for example, 30% of the ride is uphill, another 30% is downhill and 40% is flat.

3. How the work is shared between you and the motor

Pedal-assist motors multiply what you put in. On Bosch motors, Eco adds between 40 and 60% of your power, Tour between 100 and 140%, Sport between 170 and 240% and Turbo between 250 and 340%, depending on the motor. We use middle values: 55, 120, 200 and 300%. In each part of the ride:

Motor power = power needed × assist ÷ (1 + assist)

with a ceiling of 450 W of mechanical power and no assist above 15.5 mph (25 km/h). That cutoff is the European limit and is stricter than the US one (see below): at the default 12 mph (20 km/h) it makes no difference, but if you cruise faster than 15.5 mph on a Class 1, 2 or 3 bike, your motor will keep working and your real range will be lower than our estimate.

4. From power to Wh per mile

Wh/km = (motor power ÷ 0.78 + 2 W of electronics) ÷ speed × 1.10

Multiply by 1.609 to get Wh per mile. The 0.78 is the efficiency of the motor and its electronics: of every 100 Wh that leave the battery, about 78 reach the crank. The final 10% covers starts, stops at lights and changes of pace, which a constant-speed calculation can’t see.

5. Miles

Range = usable energy ÷ Wh per mile

The range runs from 20% lower to 15% higher, because there are things the model doesn’t know: your cadence, the real condition of your battery, whether the wind is gusty or whether you brake a lot.

US e-bike classes

Most US states classify e-bikes in three classes, based on model legislation promoted by PeopleForBikes: Class 1 has pedal assist only, up to 20 mph; Class 2 has a throttle that can move the bike without pedaling, also up to 20 mph; and Class 3 has pedal assist up to 28 mph. In all three, the motor must be rated under 750 W and the pedals must work. Where you can ride each class (bike paths, trails) depends on your state; check the bike laws section.

E-bike range chart

Miles (and km) in Eco / Tour / Sport / Turbo for a 165 lb (75 kg) rider, a 53 lb (24 kg) e-bike and 4.4 lb (2 kg) of load, city tire, 64 °F (18 °C), no wind and a cruising speed of 12 mph (20 km/h).

Flat: 10.6 ft of climbing per mile (2 m/km). Rolling: 63 ft per mile (12 m/km). Hilly: 132 ft per mile (25 m/km), which is what a 25-mile (40 km) ride with 3,281 ft (1,000 m) of climbing has. For the range on each figure and 545 Wh batteries, see the e-bike range chart by battery.

What drains the battery most

With a 500 Wh battery, in Tour mode and starting from the chart example, this is what each factor changes:

Wind and mode matter most. Wind because air resistance grows with the square of your speed relative to the air; mode because it decides how much of the work the motor does.

What stands out is that pedaling harder barely changes your range: since the motor multiplies what you put in, if you push harder it pushes harder too, and you simply go faster. What makes the battery last longer is dropping a mode, not pushing harder in the same one.

Tips to make your battery last longer

• Use the lowest mode that keeps you comfortable and only go up a mode on steep climbs.
• Pedal at a high cadence, above 60 rpm. Bosch says the motor works more efficiently that way; grinding a big gear uses more battery. You can check your gearing in the gear ratio calculator.
• Run the right tire pressure. A soft tire has more rolling resistance. Work it out with the tire pressure calculator, which has an e-bike profile.
• Start gently. Starts from a standstill in Turbo use a lot of energy for very little distance.
• In winter, store and charge the battery indoors, at room temperature, and put it on the bike right before you leave. Bosch advises against charging it cold. On long, cold rides, a neoprene thermal cover helps.

Common mistakes

• Trusting the “up to X miles” in the catalog. It’s usually measured in Eco, on the flat, with a light rider and good weather. Treat it as a ceiling, not an average.
• Forgetting the weight of your load. A child seat with a 33 lb (15 kg) child cuts range by about 8%.
• Reading the battery percentage on the display as if it were linear. Many displays calculate remaining miles from the last few minutes of use: after a climb in Turbo the number drops sharply, and on the flat it comes back.
• Comparing batteries by volts or amp-hours alone. What counts is energy: Wh = volts × Ah. A 36 V, 13.9 Ah battery holds about 500 Wh.

If you’re thinking of buying one

If you’re torn between an e-bike and a regular bike, the Which bike should I buy? quiz points you in the right direction based on how you ride, your terrain and your budget. And if you want it for commuting, see how much you save versus driving.

Updated October 19, 2026 ·Report an error on this page