WH to mAh Conversion: A Guide to Understanding Battery Capacity
Understanding your battery’s capacity is essential when choosing the right power station, power bank, or solar generator. Among the most commonly used energy units are watt-hours (Wh) and milliamp-hours (mAh)—but what exactly do these terms mean, and how do you convert one into the other?
Whether you’re evaluating a solar power station for your home, planning a camping trip with a portable generator, or simply comparing battery specs, learning how to convert Wh to mAh (and vice versa) will help you make smarter decisions. This guide will walk you through the basic definitions, conversion formulas, quick-reference tables, and real-world examples to help you understand and apply these units with confidence. Let’s get started by understanding what Wh and mAh really mean.
What Is Wh？
A watt-hour (Wh) is a unit of energy that measures the amount of electrical work performed or energy generated over a period of one hour. Simply put, 1 watt-hour equals the power of 1 watt consumed or produced continuously for 1 hour (1 Wh = 1 W × 1 h).
This unit is commonly used to quantify the energy capacity of electrical devices, such as batteries and generators, and to measure electricity consumption. For example, if a ceiling fan consumes 75 watts per hour and runs for 6 hours, it uses 450 watt-hours of energy (75 W × 6 h = 450 Wh).
In daily life, you may often see energy measured in kilowatt-hours (kWh), where 1 kWh equals 1,000 watt-hours. So, 2.5 kWh is the same as 2,500 Wh. Larger units like megawatt-hours (MWh) are also used for even bigger amounts of energy, with 1 MWh equaling 1 million Wh.
Although watt-hours are not part of the formal International System of Units, they are widely used in electrical applications to represent energy consumption or generation in a practical and easy-to-understand way.
What is mAh？
mAh (milliampere-hour) is a unit that measures battery capacity and is commonly used in various power banks and portable devices. It indicates how much current a battery can deliver continuously for one hour.
Think of mAh like the fuel tank of a car — the bigger the tank, the farther the car can travel without refueling. Similarly, a battery with a larger mAh capacity can power your devices for a longer period between charges.
For example, a battery rated at 10,000 mAh can theoretically supply 1,000 milliamps (or 1 amp) of current for 10 hours, or 500 milliamps for 20 hours, depending on the device’s power consumption.
It’s also important to note that mAh alone doesn’t tell the whole story since voltage plays a role in total energy. That’s why converting between mAh and watt-hours (Wh) is useful for comparing batteries of different voltages, which we’ll cover in the next sections.
How to Convert Wh to mAh?
Converting watt hours to milliamp hours (mAh) is a straightforward process once you understand the relationship between these units. Since watt-hours measure energy and milliampere-hours measure electric charge, the key factor that links them is voltage (V).
The formula to convert Wh to mAh is:
mAh=Wh×1000÷ V
Here’s what this means:
Wh is the total energy stored or consumed.
V is the voltage of the battery or device.
Multiplying by 1000 converts ampere-hours (Ah) to milliampere-hours (mAh).
Example:
If you have a battery rated at 5 Wh and 3.7 V, the conversion to mAh is:
mAh=5×1000÷ 3.7≈1351mAh
This means the battery can supply approximately 1351 milliamps for one hour at 3.7 volts.
How to Convert mAh to Wh?
Converting milliampere-hours (mAh) to watt-hours (Wh) helps you understand how much energy a battery can deliver. The formula is simple:
Watt-hours (Wh) = (mAh × V) ÷ 1000
Where:
mAh is the battery capacity in milliampere-hours
V is the voltage of the battery
1000 is used to convert milliamps to amps
Example 1:
You have a 10,000 mAh power bank with a voltage of 3.7V.
Wh = (10,000 × 3.7) ÷ 1000 = 37 Wh
Example 2:
A 5000 mAh battery rated at 5V would be:
Wh = (5000 × 5) ÷ 1000 = 25 Wh
Knowing how to convert mAh to Wh is especially useful when comparing batteries or estimating how long a device can run before needing a recharge. It allows you to compare devices on an energy basis—even if they list their capacities differently.
Conversion Table for Quick Reference
To make it easier to understand how watt-hours (Wh) convert to milliampere-hours (mAh) at common voltages, here is a quick reference table.
Watt Hours (Wh) | Voltage (V) | Milliampere Hours (mAh) |
1 Wh | 3.7 V | 270.27 mAh |
5 Wh | 3.7 V | 1351.35 mAh |
10 Wh | 3.7 V | 2702.7 mAh |
20 Wh | 3.7 V | 5405.41 mAh |
25 Wh | 3.7 V | 6756.76 mAh |
40 Wh | 3.7 V | 10810.81 mAh |
45 Wh | 3.7 V | 12162.16 mAh›› |
50 Wh | 3.7 V | 13513.51 mAh |
75 Wh | 3.7 V | 20270.27 mAh |
100 Wh | 3.7 V | 27027.03 mAh |
What’s the Use of Knowing How to Convert?
Understanding how to convert between Wh (watt-hours) and mAh (milliampere-hours) can be incredibly useful—especially when comparing batteries, estimating energy needs, or selecting portable power stations.
Compare Battery Capacities Accurately
Not all batteries list capacity the same way. Some use Wh, while others use mAh. Conversion helps you make an apples-to-apples comparison across different devices or brands.
Match Power Requirements with Devices
If you know how much energy a device needs in Wh, you can quickly determine if a battery (measured in mAh) is sufficient—just plug the values into the formula. This is crucial for selecting the right backup battery or solar generator.
Plan Energy Usage More Efficiently
For campers, travelers, or emergency planners using solar panels and portable batteries, converting between Wh and mAh ensures you don’t run out of power unexpectedly. The EcoFlow RIVER 3 Plus Portable Power Station is an ideal solution for such scenarios. For example, with its 286Wh capacity, it can power devices like laptops, phones, or a mini-fridge for extended periods. If you’re using a device that requires 100W of power for 3 hours, this battery will easily provide enough energy, with room to spare for other devices. Plus, it recharges in just 1 hour using EcoFlow’s X-Stream fast charging, ensuring you spend less time waiting and more time enjoying your outdoor adventures or preparing for emergencies. This power station makes it easier to plan your energy usage effectively without worrying about running out of juice unexpectedly.
EcoFlow RIVER 3 Plus Portable Power Station
Understand Energy Consumption
Knowing how energy is stored and used gives you better control over power management—whether it’s for small electronics or larger off‑grid systems. The EcoFlow DELTA Pro 3 Portable Power Station, with its 4,000W pure-sine output and modular 12kWh capacity, is perfect for larger energy needs. By understanding how to convert Wh to mAh, you can estimate how long the DELTA Pro 3 can power your high-energy devices. For example, with a 3,000W device, you could expect the DELTA Pro 3 to run it for over an hour, providing you with insight into long-term energy planning for your home or off-grid setup.
EcoFlow DELTA Pro 3 Portable Power Station
Conclusion
Converting Wh (watt-hours) to mAh (milliamp-hours)—and vice versa—may seem technical at first, but it's a valuable skill when dealing with batteries, power stations, or any electronic devices. Whether you're trying to compare energy capacity, plan for off-grid use, or understand product specifications, knowing how to perform these conversions ensures better decision-making.
Just remember the basic formulas:
mAh = (Wh × 1000) ÷ V
Wh = (mAh × V) ÷ 1000
By understanding both units and how to convert between them, you’ll be better equipped to evaluate energy storage and consumption, making your power choices smarter and more efficient.
FAQs
How many mAh is 1 Wh?
To convert 1 Wh (watt-hour) to mAh (milliamp-hour), you need to know the voltage (V) of the battery. The formula is:
mAh=Wh×1000÷ V
For example, with a typical lithium-ion battery voltage of 3.7 V:
mAh=1×1000÷3.7≈270 mAh
So, 1 Wh equals about 270 mAh at 3.7 volts. The exact number changes depending on the voltage used.
What does 290 Wh mean?
290 Wh (watt-hours) means the battery or device can deliver 290 watts of power for one hour, or less power over a longer time. It represents the total energy capacity.
For example, if a device consumes 29 watts, a 290 Wh battery could power it for roughly 10 hours (290 ÷ 29 = 10). If the power consumption is higher, the runtime will be shorter.
To estimate the capacity in mAh at 12 volts:
mAh=290×1000÷12≈24,167 mAh
So, 290 Wh corresponds to about 24,167 mAh at 12V.
What does 10000mAh 37 Wh mean?
A battery labeled 10000mAh 37 Wh provides two important details:
10000 mAh: the amount of electric charge the battery can hold.
37 Wh: the total energy it can deliver.
These are connected through voltage by: Wh=mAh×V÷1000
Using this, you can calculate the voltage: V=37×1000÷10000=3.7V
This means the battery runs at 3.7 volts, typical for lithium-ion batteries.
In short, a 10000mAh 37 Wh battery is a 3.7 V battery with enough capacity to charge a smartphone two to three times, depending on the phone’s battery size.
What is 20000mAh in Wh?
To convert 20000 mAh to Wh, you need the battery voltage. For most lithium-ion batteries, the voltage is about 3.7 V.
Use the formula:
Wh=mAh×V÷1000
So,
Wh=20000×3.7÷1000=74 Wh
Therefore, 20000 mAh at 3.7 volts equals 74 Wh.