About the Wh to mAh Calculator
This calculator converts Wh to mAh. Wh is one watt of power used for one hour, the unit used for the energy stored in a battery, and mAh is one thousandth of an amp-hour, the capacity figure printed on phone batteries and power banks. It divides the energy by the voltage and multiplies by 1,000 to give milliamp-hours, and also shows amp-hours. Enter your figures and the answer appears at once, together with a few related values, and you can copy the result with one tap. The sums are done in your browser and nothing is sent anywhere.
Updated October 2026
How to use the Wh to mAh Calculator
- 1Enter the value in Wh.
- 2Fill in the other boxes that the Wh to mAh calculation needs, such as time, voltage or power factor.
- 3Read the answer in the large result box.
- 4Check the extra rows for related values.
- 5Press Copy result to keep it.
When you need Wh to mAh
Airlines limit batteries by watt-hours, while phone and power bank makers advertise milliamp-hours. To see whether a power bank is allowed in hand luggage, or to compare two packs, you must convert one to the other, and you need the voltage to do it. This tool takes both numbers and gives the capacity in either unit.
It also helps when you replace a battery: if a laptop or a drone says 57 Wh and the shop lists cells in mAh at 3.7 V, the conversion shows how many cells you need. For camping, the same sum turns a 12 V battery's amp-hours into watt-hours of usable energy.
How the Wh to mAh sum works
mAh = Wh × 1,000 ÷ volts. A 11.1 Wh battery at 3.7 V holds 11.1 × 1,000 ÷ 3.7 = 3,000 mAh.
The displayed answer is rounded to six significant figures, but the sum itself is not rounded, so converting Wh to mAh and back again gives you the number you started with.
- Use the cell voltage
- Airlines use watt-hours
- mAh without volts means little
Mistakes to avoid when converting Wh to mAh
The key mistake is ignoring voltage. A mAh figure has no meaning on its own: a 10,000 mAh pack at 3.7 V holds 37 Wh, but a 10,000 mAh battery at 12 V holds 120 Wh. Always use the voltage that the mAh figure refers to, usually the cell voltage.
On phone and computer
On a phone, type in the boxes one after another and read the mAh result underneath; the Copy button puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the mAh value move. The Wh to mAh page works the same on both. The opposite step is in mAh to Wh Calculator. Battery Charge Time Calculator shows how long a charger needs, Energy Converter changes watt-hours into joules, and Power Converter handles watts.
Features
- Wh to mAh in one step
- Related values shown with the answer
- Clear messages for impossible inputs
- Copy the result with one tap
- Private: nothing is uploaded
- Works on phone and computer
Frequently asked questions
How do I convert Wh to mAh?
mAh = Wh × 1,000 ÷ volts. A 11.1 Wh battery at 3.7 V holds 11.1 × 1,000 ÷ 3.7 = 3,000 mAh.
What is the formula for Wh to mAh?
mAh = Wh × 1,000 ÷ volts. The calculator applies it exactly and rounds only the displayed answer.
What is the difference between Wh and mAh?
Wh is one watt of power used for one hour, the unit used for the energy stored in a battery. mAh is one thousandth of an amp-hour, the capacity figure printed on phone batteries and power banks. They measure different things, which is why converting from Wh to mAh needs more than a simple multiplication in some cases.
What voltage should I use for a power bank?
Use the cell voltage, usually 3.6 or 3.7 V for lithium-ion packs. The mAh figure printed on the pack refers to that voltage, not to the 5 V output.
How many Wh is 10,000 mAh?
At 3.7 V it is 10,000 × 3.7 ÷ 1,000 = 37 Wh. At 5 V, which some makers wrongly use, the figure would look like 50 Wh.
Is this Wh to mAh calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so the figures you type are not uploaded or stored. It is meant for planning and learning; for wiring or safety work, check the result against your equipment's rating plate and local rules.