mAh to Wh Conversion Explained: Simple Calculation
Need to convert mAh to Wh? Milliampere-hours (mAh) and watt-hours (Wh) are two common ways to measure battery capacity, but they tell you slightly different things. Understanding how to convert mAh to watt hours can help you choose the right power bank, estimate battery life, or make better decisions about your devices.
In this guide, you’ll learn how to convert mAh to Wh quickly and easily, why it matters, and how voltage fits into the picture. Let’s break it down in a way that actually makes sense.
What Are mAh and Wh?
Before we dive into the conversion from milliamp hours to watt hours, let’s first go through the meaning of these terms:
Milliamp-hours or mAh for batteries measures electric charge. It tells you how much current a battery can supply over time. For example, a 10,000mAh power bank can deliver 10,000 milliamps for one hour, or 1,000 milliamps (1 amp) for ten hours. The higher the mAh rating, the longer the battery can typically last—assuming the device’s power consumption remains constant.
Wh (watt-hours), on the other hand, measures the total amount of energy a battery can deliver. It takes both current and voltage into account, giving you a better sense of how much usable power is available over time. Just like you might need to figure out kW vs kWh when looking at home energy usage, Wh simply means watts multiplied by hours (W × h).
In short:
mAh measures how long a battery can run
Wh measures how much energy it actually holds
How to Convert mAh to Wh?
To convert mAh in watt hours, you’ll need to know one extra detail: the voltage of the battery. That’s because watt-hours (Wh) take both current (mAh) and voltage (V) into account.
Here’s the simple formula:
Wh = (mAh × V) ÷ 1000
Let’s break it down:
mAh is the battery’s capacity
V is the voltage (usually printed on the battery or device)
You divide by 1000 to convert from milliamp-hours to amp-hours
Example:
If you have a 10,000mAh power bank with a voltage of 3.7V:
Wh = (10,000 × 3.7) ÷ 1000 = 37 Wh
This means the power bank can deliver 37 watt-hours of energy.
Knowing how to calculate Wh from mAh can help you compare batteries more accurately—especially when you’re looking at products with different voltages or trying to meet airline limits for carrying power banks.
mAh to Wh Conversion Chart
To save you time and effort, here’s a handy chart that shows common mAh to Wh conversions at different voltage levels. Since voltage plays a key role in the formula, we’ve included two standard voltages: 3.7V (typical for lithium-ion batteries) and 5V (common for USB-powered devices).
| mAh | Wh at 3.7V | Wh at 5V |
|---|---|---|
| 1,000 | 3.7 Wh | 5 Wh |
| 2,000 | 7.4 Wh | 10 Wh |
| 5,000 | 18.5 Wh | 25 Wh |
| 10,000 | 37 Wh | 50 Wh |
| 20,000 | 74 Wh | 100 Wh |
| 26,800* | 99.16 Wh | 134 Wh |
*Note: 26,800mAh at 3.7V (99.16 Wh) is the maximum battery size allowed (100 Wh) on most commercial flights in the UK and internationally.
What Role Does Voltage Play in the Conversion?
As we’ve seen, voltage is a key part of the mAh to Wh conversion—without it, you can’t get an accurate result. That’s because mAh only tells you how much charge a battery can hold, while Wh tells you how much actual energy it can deliver. And to figure that out, you need to know the voltage.
Here’s why it matters:
Think of voltage as the “pressure” that pushes electrical current through a device. A higher voltage means more energy is delivered, even if the mAh stays the same.
For example:
A 10,000mAh battery at 3.7V = 37Wh
The same 10,000mAh battery at 5V = 50Wh
That’s a big difference!
So, when you’re converting mAh to Wh, always check the voltage printed on your battery or in the product specs. It ensures you get a true picture of how much energy the battery can actually provide.
Practical Applications of mAh to Wh Conversion
So, why does converting mAh to Wh actually matter? Because it helps you make smarter decisions about the tech you use every day or broader energy setups. Here are some real-life examples where this conversion comes in handy:
Travelling with Power Banks
Most airlines (including UK carriers) allow you to bring batteries up to 100Wh in your hand luggage. If your power bank says “20,000mAh,” is it safe to fly with?
Use the formula:
20,000mAh × 3.7V ÷ 1000 = 74WhYes, you’re well within the limit.
This quick conversion helps avoid awkward moments at airport security.
Comparing Power Banks or Batteries
You’re looking at two power banks:
One is 15,000mAh at 3.7V
The other is 12,000mAh at 5V
Which one holds more energy?
15,000 × 3.7 ÷ 1000 = 55.5Wh
12,000 × 5 ÷ 1000 = 60Wh
The second one actually stores more energy, even though it has a lower mAh rating. Knowing the Wh helps you make a smarter choice.
Planning for Off-Grid or Solar Use
When you’re off-grid—whether camping, working remotely, preparing for a power cut, or investing in greener solar energy to save on electricity bills—understanding how much energy your devices use in Wh or further calculate kWh usage helps you manage your power supply wisely.
Take the EcoFlow DELTA 2 Solar Generator as a real-world example. It combines EcoFlow portable solar panels with a high-capacity battery system, making it a brilliant choice for off-grid living or emergency backup.
The EcoFlow DELTA 2 Portable Power Station starts with a 1024Wh capacity. That’s enough to power your essentials for hours—like charging phones, running a Wi-Fi router, or even boiling a kettle. Want more? You can expand it to 2048Wh with the DELTA 2 Extra Battery, or up to 3040Wh with the DELTA Max Extra Battery.
Let’s say your laptop uses around 60Wh and a mini fridge uses 70Wh per hour. With 1024Wh to start with, you could run:
A laptop for about 17 hours
A mini fridge for around 14 hours
Or both together for 7–8 hours
And with solar panels (up to 400W), you can recharge in as little as 3–6 hours using just sunlight. The DELTA 2’s MPPT smart algorithm ensures you get the most efficient charge possible, so you're not wasting precious daylight.
This kind of setup shows why converting mAh to Wh (and vice versa) is so useful—you can match your energy needs with the power you’ve got stored, and plan accordingly.
Whether you’re prepping for an outage or going green on a camping trip, understanding your battery’s Wh capacity gives you the confidence to power through.
Conclusion
Now that you know how to convert mAh to Wh, you’re better equipped to choose the right battery pack or portable power station for your needs. Whether it’s for a weekend away or keeping your laptop running on the go, understanding this simple conversion helps you get the most from your devices. Keep the chart handy, remember the role of voltage, and you’ll be making more confident tech decisions in no time.
What is 20,000mAh in watts?
To convert 20,000mAh to watt-hours (Wh), you need to know the voltage of the battery. Most power banks use 3.7V, so the formula is: Wh = (mAh × V) ÷ 1000
Wh = (20,000 × 3.7) ÷ 1000 = 74Wh
So, 20,000mAh at 3.7V is equal to 74 watt-hours.
If the voltage is different (like 5V), the result will change:
(20,000 × 5) ÷ 1000 = 100Wh
Always check the voltage to get an accurate answer.
What’s the mAh to Wh calculator?
The mAh to Wh calculator converts milliamp-hours to watt-hours using the formula: Wh = (mAh × V) ÷ 1000. Simply enter the battery’s mAh and voltage (V) to get the energy in Wh.
How to convert Wh to mAh?
To convert Wh to mAh, use the formula: mAh = (Wh × 1000) ÷ V. For example, a 1.5Wh battery at 5V converts to 1.5 × 1000 ÷ 5 = 300mAh.