Convert between Ah, V, and Wh. Compare battery sizes instantly.
How do you calculate e-bike battery capacity in Wh? Multiply voltage (V) by amp-hours (Ah). A 36V 14Ah battery = 504 Wh. A 48V 17.5Ah battery = 840 Wh. Watt-hours (Wh) is the only reliable way to compare battery sizes across brands because different voltages with different Ah ratings can store the same energy. Enter your battery specs below to calculate capacity and see how it compares.
Most e-bike listings show Ah or Wh but rarely both. This calculator converts between them and shows where your battery sits compared to common Bosch, Shimano, Yamaha, and Bafang batteries.
Battery voltage
Battery capacity (Ah)
Common E-bike Battery Capacities
Branded systems (Bosch, Shimano, Yamaha, Giant) use 36V. Aftermarket systems (Bafang) commonly use 48V or 52V. Higher voltage does not mean more energy. Compare Wh to compare actual capacity.
Brand
Model
Voltage
Ah
Wh
Bosch
PowerPack 300
36V
8.3 Ah
300 Wh
Bosch
PowerPack 400
36V
11.1 Ah
400 Wh
Bosch
PowerTube 500
36V
13.9 Ah
500 Wh
Bosch
PowerTube 625
36V
17.4 Ah
625 Wh
Bosch
PowerTube 750
36V
20.8 Ah
750 Wh
Shimano
BT-E6010
36V
11.6 Ah
418 Wh
Shimano
BT-E8035
36V
14.0 Ah
504 Wh
Shimano
BT-E8036
36V
17.5 Ah
630 Wh
Yamaha
500Wh
36V
13.9 Ah
500 Wh
Yamaha
600Wh
36V
16.7 Ah
600 Wh
Giant
EnergyPak 500
36V
13.8 Ah
500 Wh
Giant
EnergyPak 750
36V
20.0 Ah
750 Wh
Bafang
Standard 48V
48V
13.0 Ah
624 Wh
Bafang
Large 48V
48V
17.5 Ah
840 Wh
Bafang
Performance 52V
52V
20.0 Ah
1040 Wh
What Is Wh and Why It Matters
Watt-hours (Wh) measure total energy a battery stores. It is the product of voltage (V) and amp-hours (Ah): Wh = V x Ah. Two batteries can look very different on paper but store the same energy. A 36V 17.4Ah battery (Bosch PowerTube 625) holds 625 Wh. A 48V 13Ah battery (Bafang) holds 624 Wh. Nearly identical capacity despite different voltage and Ah numbers. When comparing e-bike batteries or shopping for a replacement, always compare Wh. Ah alone is meaningless without knowing the voltage.
36V vs 48V vs 52V Systems
Branded e-bike systems (Bosch, Shimano, Yamaha, Brose, Giant) all use 36V. Aftermarket and DIY systems (Bafang, Luna Cycle) commonly use 48V or 52V. Higher voltage means the motor draws less current for the same power output, which can be more efficient and generate less heat. However, higher voltage does not automatically mean more range. Range depends on total Wh, not voltage alone. A 36V 750Wh Bosch battery provides more range than a 48V 624Wh Bafang battery despite lower voltage.
How Battery Capacity Affects Range
A rough rule of thumb: divide Wh by 10 to 20 to estimate range in km. At 10 Wh per km (high assist, hills, heavy rider), a 500 Wh battery gives approximately 50 km. At 20 Wh per km (eco mode, flat terrain, light rider), the same battery gives approximately 100 km. Real consumption depends on assist level, terrain, wind, rider weight, tyre pressure, and temperature. For a more precise range estimate, use the E-bike Range Calculator.
Finding Your Battery Specs
Your battery's voltage and Ah are printed on a label on the battery itself or in the owner's manual. Look for a sticker with specifications. Bosch labels show both Wh and Ah. Shimano typically shows Wh. Bafang aftermarket batteries usually show voltage and Ah. If you only see Wh (e.g. "500Wh"), divide by the system voltage to get Ah: 500 Wh divided by 36V = 13.9 Ah.
Related E-bike Tools
To estimate how many seasons your battery has left based on age and usage, use the E-bike Battery Life Estimator. If your battery is showing symptoms like reduced range, charging failures, or cutoffs, the E-bike Battery Health Checker diagnoses the specific cause. For a realistic range estimate based on your battery Wh, rider weight, and terrain, the E-bike Range Calculator uses a physics-based model. For eMTB riders, the eMTB Tyre Pressure Calculator accounts for the extra weight of the motor and battery.
Frequently asked questions
How do you calculate Wh from Ah?
Multiply Ah by voltage. Wh = Ah x V. Example: 14 Ah x 36V = 504 Wh. This is the total energy capacity of the battery.
Is a higher Ah battery always better?
Not necessarily. Ah must be compared at the same voltage. A 13Ah battery at 48V (624 Wh) stores more energy than a 14Ah battery at 36V (504 Wh). Always compare Wh for an accurate capacity comparison.
What is a good Wh for an e-bike?
400 to 500 Wh for city commuting (30 to 60 km range). 500 to 750 Wh for longer rides and hilly terrain. 750 Wh and above for touring and eMTB. Most mid-range e-bikes come with 500 to 625 Wh batteries.
How many Ah is a Bosch 625 battery?
17.4 Ah at 36V. Bosch PowerTube 625 = 36V x 17.4 Ah = 625.4 Wh (rounded to 625 Wh).
What voltage is best for an e-bike?
36V for branded systems (Bosch, Shimano, Yamaha). 48V for aftermarket and higher-power setups. 52V for maximum performance (higher top speed and hill climbing torque). Higher voltage is more efficient at high power but requires compatible components.
How do I compare batteries from different brands?
Compare Wh only. Ignore Ah and voltage in isolation. A Bosch PowerTube 625 (36V, 17.4 Ah, 625 Wh) and a Bafang 48V 13 Ah (624 Wh) have nearly identical capacity despite different specs.
Battery specifications are based on manufacturer data as of 2026 and may vary by production batch. Actual usable capacity is typically 90 to 95% of rated capacity due to BMS reserves. Range estimates are approximate.