Battery Capacity Converter

Battery capacity conversions are essential for electronics, electric vehicles, and energy storage. Different applications use various units (mAh, Ah, Wh, kWh), and understanding these conversions is crucial for device selection, power management, and comparing battery technologies.

Common Battery Capacity Units

Charge Units

Milliampere-hour (mAh) - Small batteries
Ampere-hour (Ah) - Larger batteries
Coulomb (C) - SI base unit
Faraday (F) - Electrochemistry

Energy Units

Watt-hour (Wh) - Energy capacity
Kilowatt-hour (kWh) - Large batteries, EVs
Joule (J) - SI energy unit

Common Applications

Field	Common Units	Typical Uses
Mobile Devices	mAh, Wh	Smartphones, tablets, laptops
Electric Vehicles	kWh, Ah	Battery packs, range calculation
Power Tools	Ah, Wh	Cordless tools, runtime
Energy Storage	kWh, MWh	Grid storage, backup systems

Conversion Tips

1 ampere-hour equals 1000 milliampere-hours
Watt-hours = Ampere-hours × Voltage
1 kilowatt-hour equals 1000 watt-hours
Remember that actual capacity may vary with usage conditions

Battery Capacity Conversions

Conversion	Formula	Quick Answer
mAh to Ah	mAh ÷ 1000 = Ah	Divide mAh by 1000
Ah to mAh	Ah × 1000 = mAh	Multiply Ah by 1000
Ah to Wh	Ah × Voltage = Wh	Multiply Ah by voltage
Wh to Ah	Wh ÷ Voltage = Ah	Divide Wh by voltage
Wh to kWh	Wh ÷ 1000 = kWh	Divide Wh by 1000
kWh to Wh	kWh × 1000 = Wh	Multiply kWh by 1000
Wh to J	Wh × 3600 = J	Multiply Wh by 3600
J to Wh	J ÷ 3600 = Wh	Divide J by 3600
Coulomb to Ah	C ÷ 3600 = Ah	Divide C by 3600
Ah to Coulomb	Ah × 3600 = C	Multiply Ah by 3600

Our battery capacity conversion tool provides accurate conversions between all major battery units, making it easy to compare, design, and select batteries for any application. Always consider voltage and energy requirements for the best results.

Battery Capacity Questions

Everything you need to know about battery capacity measurements and conversions

What is the difference between mAh and Wh?

mAh (milliampere-hours) measures electric charge capacity, while Wh (watt-hours) measures energy capacity. mAh tells you how much current a battery can deliver over time, while Wh tells you total energy stored. To convert between them, you need to know the voltage: Wh = (mAh × Voltage) ÷ 1000.

Why can't I convert directly between mAh and Wh?

Direct conversion between mAh and Wh requires knowing the battery voltage. mAh measures charge capacity (current × time), while Wh measures energy capacity (power × time). The relationship is: Energy (Wh) = Charge (Ah) × Voltage (V). Without voltage information, the conversion is impossible.

How do I compare batteries with different voltages?

To compare batteries with different voltages, use Wh (watt-hours) rather than mAh. Calculate Wh by multiplying Ah by voltage. For example, a 3000mAh 3.7V battery has 11.1Wh, while a 2000mAh 7.4V battery has 14.8Wh - the second battery actually stores more energy despite lower mAh.

What is battery capacity degradation?

Battery capacity naturally decreases over time and charge cycles. Lithium-ion batteries typically retain 80% of original capacity after 300-500 cycles. Factors affecting degradation include temperature, charge/discharge rates, depth of discharge, and storage conditions. Higher temperatures and deeper discharges accelerate degradation.

How accurate are battery capacity ratings?

Manufacturer capacity ratings are typically measured under ideal laboratory conditions. Real-world capacity can vary ±5-10% due to manufacturing tolerances, temperature, discharge rate, and age. Higher discharge rates generally result in lower effective capacity due to internal resistance and heat generation.

What is C-rate in battery specifications?

C-rate indicates how fast a battery charges or discharges relative to its capacity. 1C means the battery fully discharges in 1 hour, 2C in 30 minutes, 0.5C in 2 hours. For a 1000mAh battery: 1C = 1000mA, 2C = 2000mA, 0.5C = 500mA. Higher C-rates may reduce effective capacity and battery lifespan.

How do I calculate battery runtime?

Basic runtime = Battery capacity (Ah) ÷ Device current draw (A). For example, a 2000mAh battery powering a 500mA device: 2Ah ÷ 0.5A = 4 hours. However, actual runtime is typically 80-90% of calculated due to efficiency losses, voltage drops, and battery characteristics.

What is the difference between nominal and actual capacity?

Nominal capacity is the manufacturer's rated capacity under standard conditions (usually 20-hour discharge at room temperature). Actual capacity varies with discharge rate, temperature, and battery age. Fast discharge reduces capacity, cold temperatures can reduce it by 20-50%, and aged batteries provide less than nominal capacity.

Have more questions? Contact us!