Battery Capacity Converter
Use this calculator to convert between milliampere-hours (mAh) and kilowatt-hours (kWh) for batteries.
Understanding Battery Capacity: mAh vs. kWh
When dealing with batteries, especially in electronics and electric vehicles, you'll encounter two common units for capacity: milliampere-hours (mAh) and kilowatt-hours (kWh). While both measure how much energy a battery can store, they operate on different scales and are often used for different applications.
Milliampere-Hours (mAh)
Milliampere-hours (mAh) is a unit of electric charge. It represents the amount of current (in milliamperes) a battery can deliver over a period of one hour. For example, a 5000 mAh battery can theoretically supply 5000 mA (or 5 A) of current for one hour, or 1000 mA (or 1 A) for five hours, and so on.
mAh is commonly used for smaller batteries found in portable electronic devices like smartphones, power banks, and wireless earbuds. It's a useful metric for comparing the capacity of similar-voltage batteries within these devices.
Kilowatt-Hours (kWh)
Kilowatt-hours (kWh) is a unit of energy. It represents the amount of energy consumed or stored by a device drawing a power of one kilowatt for one hour. One kilowatt is equal to 1000 watts. So, a 1 kWh battery can deliver 1000 watts of power for one hour, or 500 watts for two hours.
kWh is typically used for larger capacity batteries, such as those found in electric vehicles (EVs) or home energy storage systems. It provides a more practical measure of the total energy content for high-power applications.
The Relationship: Voltage is Key
The conversion between mAh and kWh depends on the battery's voltage. The fundamental relationship is: Energy (Wh) = Capacity (Ah) × Voltage (V)
Since 1 Ah = 1000 mAh and 1 kWh = 1000 Wh, we can derive the conversion formulas:
- To convert mAh to kWh:
- To convert kWh to mAh:
kWh = (mAh / 1000) * V / 1000
mAh = kWh * 1000 * V * 1000
Understanding these units helps you better assess battery performance and choose the right power solutions for your needs.
Example Calculation:
Let's say you have a typical smartphone battery with a nominal voltage of 3.7V and a capacity of 5000 mAh.
Converting mAh to kWh:
Capacity in Ah = 5000 mAh / 1000 = 5 Ah
Energy in Wh = 5 Ah * 3.7 V = 18.5 Wh
Energy in kWh = 18.5 Wh / 1000 = 0.0185 kWh
This means a 5000 mAh, 3.7V battery stores approximately 0.0185 kWh of energy.
Now, suppose an electric car battery has a capacity of 75 kWh and operates at a nominal voltage of 400V.
Converting kWh to mAh:
Energy in Wh = 75 kWh * 1000 = 75000 Wh
Capacity in Ah = 75000 Wh / 400 V = 187.5 Ah
Capacity in mAh = 187.5 Ah * 1000 = 187500 mAh
This electric car battery has a capacity equivalent to 187,500 mAh at 400V.