mAh to Wh Converter

Convert milliamp-hours to watt-hours instantly with voltage input

Electric Charge

mAh

Voltage

Energy Output

0 Wh

Quick Conversions

How to Convert mAh to Wh

Converting milliamp-hours (mAh) to watt-hours (Wh) requires knowledge of the battery voltage. The electric charge capacity measured in mAh indicates how long a battery can deliver current, while energy capacity in Wh shows the total electrical power available.

Wh = (mAh × V) ÷ 1000

Where Wh is watt-hours, mAh is milliamp-hours, and V is voltage

Conversion Steps

Identify the battery capacity in milliamp-hours (mAh) from the battery label or specifications
Find the nominal voltage (V) of the battery, typically printed on the device or battery casing
Multiply the mAh value by the voltage to get milliwatt-hours (mWh)
Divide the result by 1000 to convert milliwatt-hours to watt-hours
The final value represents the total energy capacity of the battery in Wh

Example Calculation:
A smartphone battery has 4000 mAh capacity at 3.8V voltage.

Step 1: Multiply 4000 mAh × 3.8V = 15,200 mWh
Step 2: Divide 15,200 ÷ 1000 = 15.2 Wh

Result: The battery stores 15.2 watt-hours of energy

Common Battery Conversions

This reference chart shows typical battery sizes with their mAh ratings, voltage levels, and corresponding energy capacity in watt-hours.

Battery Type	Capacity (mAh)	Voltage (V)	Energy (Wh)
AA Alkaline	2,700	1.5	4.05
AAA Alkaline	1,200	1.5	1.8
AAAA Alkaline	625	1.5	0.94
C Battery	8,000	1.5	12
D Battery	12,000	1.5	18
9V Battery	565	9	5.09
iPhone 13	3,227	3.83	12.36
Samsung S21	4,000	3.85	15.4
Laptop Battery	5,000	11.4	57
Power Bank 10K	10,000	3.7	37
Power Bank 20K	20,000	3.7	74
Electric Car (Tesla Model 3)	50,000,000	350	17,500

mAh to Wh Conversion Chart

Use this quick reference table for common mAh values at standard lithium-ion battery voltage (3.7V).

mAh	Wh at 3.7V	Wh at 7.4V	Wh at 11.1V
500	1.85	3.7	5.55
1,000	3.7	7.4	11.1
2,000	7.4	14.8	22.2
3,000	11.1	22.2	33.3
4,000	14.8	29.6	44.4
5,000	18.5	37	55.5
6,000	22.2	44.4	66.6
8,000	29.6	59.2	88.8
10,000	37	74	111
15,000	55.5	111	166.5
20,000	74	148	222
25,000	92.5	185	277.5
30,000	111	222	333

Why Voltage Matters

Voltage plays a critical role in the mAh to Wh conversion because it determines how much energy each unit of charge delivers. Two batteries with identical mAh ratings but different voltages will store vastly different amounts of energy.

Consider these examples:

Scenario 1: 5000 mAh battery at 3.7V
Energy = (5000 × 3.7) ÷ 1000 = 18.5 Wh

Scenario 2: 5000 mAh battery at 7.4V
Energy = (5000 × 7.4) ÷ 1000 = 37 Wh

The second battery stores twice the energy despite having the same mAh rating.

Always check the nominal voltage printed on the battery label. Common battery voltages include:

Related Energy Conversions

Explore other battery and energy unit conversions to compare different power specifications.

Frequently Asked Questions

What is the difference between mAh and Wh?

mAh (milliamp-hours) measures electric charge capacity – how much current a battery can deliver over time. Wh (watt-hours) measures energy capacity – the total power available. Wh provides a more accurate comparison between batteries with different voltages because it accounts for both charge and voltage.

How do I find my battery voltage?

Battery voltage is usually printed directly on the battery casing or label. For smartphones and tablets, check the device specifications in settings or the manufacturer website. If unavailable, consult the user manual or contact the manufacturer. Common lithium-ion batteries use 3.7V or 3.8V nominal voltage.

Can I convert Wh back to mAh?

Yes, the reverse formula is: mAh = (Wh × 1000) ÷ V. For example, a 15 Wh battery at 3.7V equals (15 × 1000) ÷ 3.7 = 4,054 mAh. You must know the voltage for accurate conversion in either direction.

Why do airlines limit batteries by Wh instead of mAh?

Airlines use watt-hour limits because Wh measures actual energy content, which determines fire risk. Two power banks with the same mAh but different voltages carry different energy amounts. Most airlines allow batteries up to 100 Wh in carry-on luggage, with 100-160 Wh requiring approval.

What does a 10000mAh power bank really mean?

A 10,000 mAh power bank at 3.7V contains 37 Wh of energy. However, due to voltage conversion and efficiency losses (typically 85-90%), you receive around 31-33 Wh of usable power. This can charge a 3,000 mAh phone (11.1 Wh at 3.7V) approximately 2.8 to 3 times.

Which is better for comparing batteries: mAh or Wh?

Wh is superior for comparing batteries with different voltages because it represents total energy capacity. mAh only works for direct comparison when batteries share identical voltage. For instance, a 5,000 mAh battery at 7.4V (37 Wh) outlasts a 10,000 mAh battery at 3.7V (37 Wh) – they contain equal energy despite different mAh ratings.

Does temperature affect the mAh to Wh conversion?

The mathematical conversion remains constant, but temperature affects actual battery performance. Cold temperatures reduce available capacity, while excessive heat can damage batteries. The voltage may also vary slightly under different temperatures, though nominal voltage ratings remain the standard for calculations.

What voltage should I use for lithium polymer batteries?

Lithium polymer (LiPo) batteries typically have a nominal voltage of 3.7V per cell. Fully charged, they reach 4.2V, and discharged down to 3.0V safely. Always use the nominal voltage (3.7V) for capacity calculations. Multi-cell packs multiply this value: 2S = 7.4V, 3S = 11.1V, 4S = 14.8V.

Practical Applications

Smartphone Charging

Calculate how many times a power bank can charge your phone. Divide the power bank Wh by your phone battery Wh, then multiply by 0.85 to account for efficiency loss. A 37 Wh power bank can charge a 11.1 Wh phone approximately 2.8 times.

Air Travel Regulations

Airlines restrict lithium batteries based on watt-hour ratings. TSA and most international airlines allow batteries up to 100 Wh in carry-on luggage without approval. Batteries between 100-160 Wh require airline approval and are limited to 2 per passenger. Checked baggage prohibits spare lithium batteries entirely.

Solar Power Systems

When designing off-grid solar installations, battery banks are specified in watt-hours to match daily energy consumption. A household using 5 kWh daily needs battery storage providing at least that capacity, accounting for depth of discharge limits and inefficiencies.

Electric Vehicles

EV batteries are always rated in kilowatt-hours (kWh) because of their high capacity. A Tesla Model 3 with a 60 kWh battery pack at 350V nominal voltage technically has 171,428 Ah (171,428,000 mAh) capacity, demonstrating why Wh is more practical for large batteries.

Drone Flight Time

Drone pilots calculate flight time by dividing battery Wh by average power consumption in watts. A drone consuming 100W powered by a 74 Wh battery (20,000 mAh at 3.7V) provides approximately 44 minutes of flight time theoretically, though real-world conditions reduce this.