Battery Capacity Ah vs Wh - What Do the Parameters Mean? 🔋 Calculator and Guide 2025

July 29, 2025

Battery capacity Ah vs Wh - what do the parameters mean?

Complete Guide to Electric Bike Battery Capacity Units with Calculator

When purchasing an electric bike battery, you'll encounter various units of capacity—Ah, Wh, and sometimes mAh. What do these abbreviations mean? Which unit is more important? And how do you convert one to the other? In this guide, we'll explain everything in simple terms and provide a handy conversion calculator.

Basic units of battery capacity

Ampere-hour

A unit of electrical charge. It measures how much current (in amperes) a battery can deliver in one hour. For example, a 10Ah battery can deliver 10A for 1 hour or 5A for 2 hours.

Watt-hour

A unit of electrical energy. It represents the total amount of energy stored in a battery. It is the best measure for comparing batteries of different voltages.

Volt

A unit of electrical voltage. Electric bikes most commonly use 36V, 48V, or 52V batteries. Voltage affects the bike's power and speed.

Battery capacity calculator

Battery voltage

Volts (V)

Capacity

Ampere-hours (Ah)

Total energy:

360

Watt-hours (Wh)

Conversion formula:

Wh = V × Ah

Examples of popular e-bike batteries

Primary battery

Voltage: 36V
Capacity: 10Ah
Energy: 360Wh
Range: about 40-60 km

Medium battery

Voltage: 48V
Capacity: 13Ah
Energy: 624Wh
Range: about 70-100 km

Premium battery

Voltage: 48V
Capacity: 20Ah
Energy: 960Wh
Range: about 120-160 km

Expert Tip

When comparing bike batteries, always look at the Wh rating, not just the Ah! A 36V 15Ah (540Wh) battery has less energy capacity than a 48V 13Ah (624Wh) battery, even though it has more amp-hours.

What is more important - Ah or Wh?

Watt-hours (Wh) are the most important parameter when choosing an electric bike battery. Wh determines the actual amount of energy in the battery and directly translates into the bike's range. Why?

✓ Wh takes voltage into account - two batteries with the same Ah capacity but different voltage will have different amounts of energy
✓ Easier comparison - you can compare 36V and 48V batteries directly by Wh value
✓ Range prediction - knowing Wh and average energy consumption allows you to accurately estimate range

Battery Comparison - Practical Example

Battery model	Tension	Capacity Ah	Energy Wh	Estimated range
REACTOR 36V 10.4Ah	36V	10.4Ah	374Wh	40-60 km
REACTOR 36V 13Ah Trunk	36V	13Ah	468Wh	50-70 km
REACTOR 36V 15.6Ah	36V	15.6Ah	562Wh	60-85 km
REACTOR 36V 20Ah LongRange™	36V	20Ah	720Wh	80-110 km
REACTOR 48V 13Ah	48V	13Ah	624Wh	70-95 km
REACTOR 48V 17.5Ah	48V	17.5Ah	840Wh	90-125 km
REACTOR 48V 18.2Ah LongRange™	48V	18.2Ah	874Wh	95-130 km
REACTOR 48V 20Ah LongRange™	48V	20Ah	960Wh	100-140 km

Important information about coverage

The stated ranges are approximate and depend on many factors: assist level, rider weight, terrain, temperature, tire pressure, and riding style. Actual range may vary by ±30%.

Other units you may encounter

mAh

Milliampere-hour

1000 mAh = 1 Ah. Often used in small batteries (phones, flashlights). Rarely found in electric bikes.

kWh

Kilowatt-hour

1 kWh = 1000 Wh. Primarily used in electric cars. A 960Wh battery is 0.96 kWh.

C-index

Specifies the maximum discharge current. For example, a 10Ah battery at 2C can deliver a maximum of 20A of current.

How to choose the right battery capacity?

Capacity selection recommendations

Up to 400Wh - city driving, short distances up to 50km
400-600Wh - universal use, distances 50-80km
600-800Wh - long trips, off-road driving, 80-120km
Above 800Wh - bicycle touring, very long distances over 120km

Frequently asked questions about battery capacity

Can I use a battery with a higher voltage than the factory one? ▼

We don't recommend this. The controller and motor are designed for a specific voltage. Using a battery with a higher voltage may damage the bike's electronics and void the warranty. Always use batteries with a voltage that meets the manufacturer's specifications.

Why does my 10Ah battery have a shorter range than my friend's 10Ah battery? ▼

The batteries likely have different voltages. A 36V 10Ah battery has 360Wh of energy, while a 48V 10Ah battery has 480Wh—a whopping 33% more energy! Always compare batteries by Wh, not just Ah.

Does more battery capacity mean more weight? ▼

Yes, typically, higher capacity comes with increased weight. Every 100Wh adds about 0.5-0.7kg (1.1-1.7lbs) depending on the cell technology. A 500Wh battery weighs about 2.5-3kg (5.7-7.8lbs), and a 1000Wh battery weighs about 5-6kg (13-14lbs).

How to calculate range based on battery capacity? ▼

As a rough guide, 1km of riding with medium power assist consumes 8-12Wh of energy. So, a 500Wh battery will allow you to travel about 40-60km. In eco mode, consumption drops to 5-8Wh/km, and in turbo mode, it increases to 15-20Wh/km.

Summary

When choosing an electric bike battery, always pay attention to the Wh (watt-hour) rating , which indicates the actual amount of energy in the battery. Wh directly translates to your e-bike's range. Also, remember the formula: Wh = V × Ah , which will allow you to quickly calculate battery parameters.

Use our calculator above to easily convert units and compare different bike batteries. Choose the capacity that best suits your needs – don't overpay for unnecessary capacity, but don't skimp on ride comfort either.

Find the perfect battery for you!

Check out our range of REACTOR batteries from 374Wh to 960Wh

See all batteries

Back to blog