Battery Capacity & Energy
Convert mAh · Ah · Wh
Input
Result
—
- Capacity (mAh)
- —
- Amp-hours (Ah)
- —
- Energy (Wh)
- —
Wh = Ah × V · Ah = mAh ÷ 1000
Everything is calculated in your browser. Your values are not sent to or stored on a server.
How to use
Converts between mAh and Wh for power banks and laptop batteries, using Wh = Ah × V once you supply the voltage. Nothing is uploaded.
When to use it
- Checking whether a power bank is allowed on a plane (commonly a 100Wh limit).
- Comparing capacities quoted in different units.
- Estimating mAh when a spec sheet lists only Wh.
How to use it
- Choose a direction — mAh to Wh, or Wh to mAh.
- Enter the capacity and the voltage.
- The result appears immediately, with the formula shown.
Good to know
- mAh alone cannot compare energy. At different voltages the same mAh holds different energy, which is exactly why airlines measure in Wh.
- Power bank cells are usually 3.6–3.7V while the output is 5V. Use the voltage printed on the product.
- Usable energy is lower than the rated capacity because of conversion losses; this calculation uses the rated figure.
- Airline rules vary by carrier and country. Treat this as a guide and check the airline before you fly.
Frequently asked questions
Can I take a 20,000mAh power bank on a plane?
It depends on the voltage. At 3.7V, 20,000mAh × 3.7 ÷ 1000 = 74Wh, under the common 100Wh limit. Rules and quantity limits differ by airline, so confirm with yours.
Two banks with the same mAh last different times.
Different voltages or different conversion losses. A power bank converts 3.7V cell power to 5V, losing some along the way, so only around 60–70% of the printed mAh typically reaches your phone.
How do Ah and mAh relate?
1Ah = 1,000mAh. Laptop batteries are usually quoted in Ah or Wh, power banks in mAh.
Can it estimate charging time?
Charging time depends on the charger, cable, temperature and battery condition, so a number derived from capacity alone would not be trustworthy — which is why it is not offered.