mAh to kWh Converter

Converting milliampere-hours (mAh) to kilowatt-hours (kWh) helps you understand battery energy capacity in practical terms. Whether you’re comparing smartphone batteries, power banks, or electric vehicle cells, this conversion shows how much actual energy your device stores.

Milliampere-hours (mAh)

Voltage (V)

Common Voltage Presets

Quick Conversions (3.7V)

Result

0 kWh

Recent Conversions

mAh to kWh Conversion Table

These tables show common battery capacities converted to kilowatt-hours at different voltages.

At 3.7V (Smartphone & Li-ion Batteries)

mAh	Voltage (V)	kWh
500 mAh	3.7 V	0.001850 kWh
1,000 mAh	3.7 V	0.003700 kWh
2,000 mAh	3.7 V	0.007400 kWh
3,000 mAh	3.7 V	0.011100 kWh
4,000 mAh	3.7 V	0.014800 kWh
5,000 mAh	3.7 V	0.018500 kWh
10,000 mAh	3.7 V	0.037000 kWh
20,000 mAh	3.7 V	0.074000 kWh

At 5V (USB Power Banks)

mAh	Voltage (V)	kWh
5,000 mAh	5 V	0.025000 kWh
10,000 mAh	5 V	0.050000 kWh
15,000 mAh	5 V	0.075000 kWh
20,000 mAh	5 V	0.100000 kWh
25,000 mAh	5 V	0.125000 kWh
30,000 mAh	5 V	0.150000 kWh

At 12V (Automotive Batteries)

mAh	Voltage (V)	kWh
10,000 mAh	12 V	0.120000 kWh
20,000 mAh	12 V	0.240000 kWh
50,000 mAh	12 V	0.600000 kWh
100,000 mAh	12 V	1.200000 kWh

Conversion Formula & Steps

The conversion from mAh to kWh requires voltage because energy depends on both charge and electrical potential.

kWh = (mAh × V) ÷ 1,000,000

Where:
• kWh = kilowatt-hours (energy)
• mAh = milliampere-hours (charge capacity)
• V = voltage in volts

Step-by-Step Conversion

Take your battery capacity in milliampere-hours (mAh)
Multiply by the battery voltage (V)
Divide the result by 1,000,000
The answer is your energy capacity in kilowatt-hours (kWh)

Worked Example

Let’s convert a typical smartphone battery: 4,000 mAh at 3.7V.

Start with 4,000 mAh and 3.7V
Multiply: 4,000 × 3.7 = 14,800
Divide: 14,800 ÷ 1,000,000 = 0.0148
Result: 0.0148 kWh

This means your phone battery stores roughly 0.015 kilowatt-hours of energy. Charging it fully costs about 0.2p at typical UK electricity rates.

What You Need to Know

Why Voltage Matters

You can’t convert mAh to kWh without knowing voltage. That’s because mAh measures electrical charge (how many electrons flow), whilst kWh measures energy (the work those electrons can do). A 10,000 mAh battery at 3.7V stores different energy than the same capacity at 12V.

Common Battery Voltages

Smartphones and tablets: 3.7V or 3.8V (lithium-ion)
USB power banks: rated at 5V output, but internal cells are 3.7V
Laptop batteries: 7.4V, 11.1V, or 14.8V (multiple cells)
Car batteries: 12V (lead-acid)
E-bike batteries: 24V, 36V, or 48V
AA/AAA rechargeable: 1.2V (NiMH)

Real-World Context

Battery capacity in kWh helps you compare across different devices. A 5,000 mAh phone battery at 3.7V equals 0.0185 kWh. That’s tiny compared to an electric car with a 60 kWh battery pack, which is equivalent to roughly 3,200 smartphone charges.

Everyday Examples

Smartphones

Modern phones pack 3,000 to 5,000 mAh batteries at 3.7V. That’s 0.011 to 0.019 kWh per charge. At 20p per kWh (average UK rate), charging your phone costs less than half a penny.

Power Banks

A 20,000 mAh power bank rated at 3.7V holds 0.074 kWh. But when it outputs at 5V through USB, efficiency losses mean you’ll get about 60-70% of that rated capacity to your devices.

Laptops

Laptop batteries range from 40,000 to 60,000 mAh at higher voltages (7.4V to 11.1V). A typical 50,000 mAh at 11.1V equals 0.555 kWh — enough to run your laptop for 6-10 hours depending on workload.

Electric Vehicles

An EV battery might be 60 kWh. Converting back, that’s 60,000,000 mAh at 1V, or more practically, 16.2 million mAh at 370V (a typical EV voltage). This shows why we use kWh for large batteries — the mAh numbers become unmanageable.

Units Of Energy Conversions

When working with battery capacity and energy, you’ll encounter several related units.

From	To	Multiply by
mAh to Ah	Amp-hours	÷ 1,000
mAh to Wh	Watt-hours	× V ÷ 1,000
mAh to kWh	Kilowatt-hours	× V ÷ 1,000,000
Wh to kWh	Kilowatt-hours	÷ 1,000
Ah to mAh	Milliamp-hours	× 1,000
kWh to Wh	Watt-hours	× 1,000

Related Capacity Conversions

1 kWh = 1,000 Wh
1 Ah = 1,000 mAh
1 Wh = V × Ah
1 kWh = 3.6 MJ (megajoules)
1 kWh = 860 kcal (kilocalories)

FAQs

Can I convert mAh to kWh without voltage?

No. You need voltage to convert mAh to kWh because mAh measures charge whilst kWh measures energy. The same mAh at different voltages stores different amounts of energy.

Is a 10,000 mAh power bank really 10,000 mAh?

Sort of. The 10,000 mAh rating refers to the internal battery cells at 3.7V. When the power bank converts this to 5V USB output, you’ll only get about 6,000-7,000 mAh delivered to your device due to conversion losses.

Why are kWh used for electric cars but mAh for phones?

It’s about scale. Phone batteries are tiny (0.01-0.02 kWh), so mAh gives convenient numbers. Car batteries are huge (40-100 kWh), making mAh impractical. Both units measure the same thing — just different magnitudes.

How many mAh equals 1 kWh?

It depends on voltage. At 3.7V: 270,270 mAh = 1 kWh. At 5V: 200,000 mAh = 1 kWh. At 12V: 83,333 mAh = 1 kWh. Higher voltage needs fewer mAh for the same energy.

Does battery age affect the mAh to kWh conversion?

The conversion formula stays the same, but degraded batteries lose capacity. An old phone battery might drop from 3,000 mAh to 2,400 mAh. The voltage typically remains stable, so you just convert the new reduced capacity.

What’s the difference between mAh and kWh?

mAh (milliampere-hours) measures electrical charge — how much current flows. kWh (kilowatt-hours) measures energy — actual work the battery can perform. You need voltage to connect them because energy equals charge times voltage.

How much does it cost to charge a 5,000 mAh battery?

A 5,000 mAh battery at 3.7V equals 0.0185 kWh. At 20p per kWh (average UK rate), that’s 0.37p per charge. Even charging daily for a year costs only £1.35.

Can I add mAh from multiple batteries?

Only if they’re the same voltage and connected in parallel. Two 2,000 mAh batteries at 3.7V in parallel give you 4,000 mAh at 3.7V. In series, voltage doubles but mAh stays the same.