Battery Capacity Converter
Convert battery capacity between mAh, Ah, Wh, and kWh with voltage selection.
mAh (Milliampere-hour)
5,000
Ah (Ampere-hour)
5
Wh (Watt-hour)
18.5
kWh (Kilowatt-hour)
0.0185
Formulas
Wh = (mAh × V) ÷ 1000
Ah = mAh ÷ 1000
Calculated using 3.7V reference voltage
About this tool
Battery capacity represents the amount of electrical energy a battery can store and deliver. Understanding battery capacity is essential in our increasingly mobile world, where smartphones, laptops, power banks, and electric vehicles depend on reliable energy measurements. This tool simplifies the conversion between mAh (milliampere-hours), Ah (ampere-hours), Wh (watt-hours), and kWh (kilowatt-hours)—the four most common units used to describe battery capacity across consumer electronics, automotive, and renewable energy applications.
Whether you're shopping for a new device, comparing battery specifications across products, or working on electrical projects, knowing how to convert between capacity units helps you make informed decisions. Engineers designing electronic products need to specify batteries in units appropriate to their industry, while consumers comparing portable chargers or electric vehicles benefit from understanding energy measurements. The tool automatically accounts for voltage, which is critical because the same mAh rating at different voltages stores different amounts of energy.
This converter is indispensable for anyone involved with battery technology: electrical engineers optimizing power systems, product managers selecting batteries for devices, students learning about energy storage, and consumers evaluating battery options. The tool works with standard voltages from Li-ion phones to lead-acid vehicles and scales from small consumer batteries to large-capacity storage systems, making it useful across virtually every domain where batteries play a role.
Frequently Asked Questions
Code Implementation
def convert_battery_capacity(value: float, from_unit: str, to_unit: str,
voltage: float = 3.7) -> float:
"""
Convert battery capacity between mAh, Ah, Wh, kWh.
voltage is required for mAh/Ah <-> Wh/kWh conversions.
"""
# Convert to milliwatt-hours as base
if from_unit == "mAh":
base_mwh = value * voltage
elif from_unit == "Ah":
base_mwh = value * 1000 * voltage
elif from_unit == "Wh":
base_mwh = value * 1000
elif from_unit == "kWh":
base_mwh = value * 1_000_000
else:
raise ValueError(f"Unknown unit: {from_unit}")
if to_unit == "mAh":
return base_mwh / voltage
elif to_unit == "Ah":
return base_mwh / (1000 * voltage)
elif to_unit == "Wh":
return base_mwh / 1000
elif to_unit == "kWh":
return base_mwh / 1_000_000
else:
raise ValueError(f"Unknown unit: {to_unit}")
# Examples
print(f"5000 mAh @ 3.7V = {convert_battery_capacity(5000, 'mAh', 'Wh'):.2f} Wh")
print(f"18.5 Wh = {convert_battery_capacity(18.5, 'Wh', 'mAh'):.0f} mAh @ 3.7V")
print(f"100 Wh = {convert_battery_capacity(100, 'Wh', 'kWh'):.4f} kWh")Comments & Feedback
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