How do you convert kWh to mAh?

To convert kilowatt-hours (kWh) to milliampere hours (mAh), you need to know the voltage. Formula: mAh = (kWh ÷ Voltage) × 1,000,000. For example, 1 kWh at 5 volts equals 200,000 mAh (1 ÷ 5 × 1,000,000 = 200,000).

Why is voltage needed for kWh to mAh conversion?

Voltage is essential because kWh measures energy (power × time) while mAh measures electric charge (current × time). Energy = Charge × Voltage, so to convert between them, you must divide or multiply by voltage. Without knowing the voltage, the conversion is impossible.

What is the difference between kWh and mAh?

kWh (kilowatt-hour) measures energy capacity - the total amount of work a battery can do. mAh (milliampere-hour) measures charge capacity - the amount of electric charge a battery can store. A 12V 100Ah (100,000 mAh) battery contains 1.2 kWh of energy (12V × 100Ah ÷ 1000 = 1.2 kWh).

How do I calculate battery capacity in kWh?

To calculate battery capacity in kWh from mAh: kWh = (mAh × Voltage) ÷ 1,000,000. For example, a 3.7V 3,000 mAh smartphone battery has 0.0111 kWh of energy (3,000 × 3.7 ÷ 1,000,000 = 0.0111 kWh or 11.1 Wh).

What voltage should I use for the conversion?

Use the nominal voltage of your battery system. Common voltages: smartphones (3.7V), laptops (11.1V or 14.8V), car batteries (12V), solar systems (12V, 24V, or 48V), power tools (18V, 20V). Check your battery specifications or device manual for the exact voltage.

Is this calculator accurate for all battery types?

Yes, this calculator provides mathematically accurate conversions between kWh and mAh for any battery type. However, actual usable capacity may be less due to battery efficiency, discharge rate, temperature, and aging. Lithium batteries typically deliver 90-95% of rated capacity, while lead-acid batteries may only deliver 50-80% depending on discharge rate.

Free kWh to mAh Calculator Online

The kWh to mAh Calculator is a specialized tool for converting between two different but related battery specifications: energy capacity (kilowatt-hours) and charge capacity (milliampere hours). This conversion is essential for comparing batteries across different voltage systems, understanding energy storage capabilities, sizing battery banks for solar and off-grid systems, and making informed decisions about battery purchases and applications.

Understanding the relationship between kWh and mAh is crucial because these units measure different aspects of battery performance. While mAh tells you how much electric charge a battery can store, kWh tells you how much actual energy (work capacity) that battery contains. The voltage of the battery system is the critical link between these two measurements, making it an essential input for accurate conversion.

Understanding the Units

Kilowatt-hour (kWh): A unit of energy representing the amount of work that can be done by one kilowatt of power sustained for one hour. It's commonly used on electricity bills and for rating large battery systems. One kWh equals 1,000 watt-hours (Wh).

Milliampere-hour (mAh): A unit of electric charge representing the amount of charge transferred by a steady current of one milliampere flowing for one hour. It's commonly used for rating smaller batteries like those in smartphones, tablets, and portable electronics. 1,000 mAh equals 1 ampere-hour (Ah).

Voltage (V): The electrical potential difference that drives current through a circuit. Battery voltage determines how much energy is stored in each unit of charge. Higher voltage means more energy per amp-hour of capacity.

The Conversion Formula

The formula for converting kilowatt-hours to milliampere hours requires voltage as an input:

mAh = (kWh ÷ Voltage) × 1,000,000

Breaking this down step by step:

Divide energy (kWh) by voltage (V) to get charge in kilowatt-hours per volt
Convert to ampere-hours: kWh ÷ V = Ah × 1,000
Convert to milliampere-hours: Ah × 1,000 = mAh
Combined: (kWh ÷ V) × 1,000,000 = mAh

Practical Examples

Example 1 - Smartphone Battery: A smartphone battery is rated at 3,000 mAh and 3.7V. What's its energy capacity in kWh?

kWh = (mAh × V) ÷ 1,000,000
kWh = (3,000 × 3.7) ÷ 1,000,000 = 0.0111 kWh (or 11.1 Wh)

Example 2 - Solar Battery Bank: You have 1 kWh of energy storage at 12V. What's the capacity in mAh?

mAh = (1 ÷ 12) × 1,000,000 = 83,333 mAh (or 83.3 Ah)

Example 3 - Electric Vehicle: A 24V electric scooter battery stores 0.5 kWh. Capacity in mAh:

mAh = (0.5 ÷ 24) × 1,000,000 = 20,833 mAh (or 20.8 Ah)

Why Voltage Matters

Voltage is the critical factor that links energy (kWh) and charge (mAh). Consider two batteries:

Battery A: 12V, 10,000 mAh = 0.12 kWh (120 Wh)
Battery B: 3.7V, 10,000 mAh = 0.037 kWh (37 Wh)

Both have the same mAh rating, but Battery A stores more than 3 times the energy because of its higher voltage. This is why you cannot compare batteries with different voltages using mAh alone—you must convert to kWh (or Wh) for accurate comparison.

Common Applications

Battery Comparison: Compare energy capacity of batteries with different voltages by converting both to kWh.
Solar System Design: Size battery banks by converting daily energy needs (kWh) to required capacity (Ah) at your system voltage.
Electric Vehicle Range: Understand how battery pack energy (kWh) relates to capacity (Ah) at the pack voltage.
Power Bank Selection: Convert power bank capacity from mAh to Wh to understand actual energy storage.
Off-Grid Systems: Calculate battery bank size needed for specific energy storage requirements.
Cost Analysis: Compare battery prices on an energy basis ($/kWh) rather than capacity basis ($/Ah).

Important Considerations

Nominal vs Actual Voltage: Use the nominal voltage (e.g., 3.7V for lithium-ion, 12V for lead-acid) rather than the charging or minimum voltage.
Battery Chemistry: Different chemistries have different voltage characteristics. Lithium-ion cells are typically 3.6-3.7V, while lead-acid cells are 2V per cell (12V for 6 cells).
Usable Capacity: Not all rated capacity is usable. Lead-acid batteries should only be discharged to 50%, while lithium batteries can safely discharge to 80-90%.
Efficiency Losses: Inverters and charge controllers introduce 10-20% efficiency losses. Account for these in system sizing.
Temperature Effects: Battery capacity decreases in cold temperatures. At 0°F (-18°C), capacity may drop to 50-60% of rated value.
C-Rating: High discharge rates reduce effective capacity. A battery discharged at 1C (1-hour rate) delivers more capacity than when discharged at 5C (12-minute rate).

Real-World Battery Specifications

Smartphone (iPhone 13): 3,240 mAh at 3.83V = 12.4 Wh (0.0124 kWh)

Laptop (MacBook Pro 16"): 99.6 Wh at 11.47V = 8,680 mAh (0.0996 kWh)

Electric Car (Tesla Model 3): 50 kWh at 350V = 142,857 mAh (142.9 Ah)

Solar Battery (12V Deep Cycle): 100 Ah at 12V = 1.2 kWh (1,200 Wh)

Power Tool Battery: 5,000 mAh at 18V = 90 Wh (0.09 kWh)

kWh to mAh Calculator

About kWh to mAh Calculator