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kWh to mAh Calculator

Convert milliamp-hours to watt-hours and kilowatt-hours (or back) for power banks, phones, power stations and batteries — and check the airline limit.

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Direction

Capacity

mAh

Cell / battery voltage

Power banks are rated in mAh at the internal cell voltage, usually 3.6–3.85 V — not the 5 V of the USB port.

Energy

— Wh

—

Watt-hours—

Kilowatt-hours—

Milliamp-hours—

Carry-on rule (FAA)—

Airline rules for spare lithium-ion batteries: up to 100 Wh allowed in carry-on; 101–160 Wh needs airline approval (max two). Check your airline.

Quick answer

Wh = mAh × volts ÷ 1,000; kWh = Wh ÷ 1,000; mAh = Wh × 1,000 ÷ volts.

20,000 mAh power bank at 3.7 V = 74 Wh (fine for carry-on)
1 kWh at 3.7 V = 270,270 mAh; at 12 V = 83,333 mAh
1 mWh (milliwatt-hour) at 3.7 V = 0.27 mAh
A 1,024 Wh portable power station is about the same energy as 14 × 20,000 mAh power banks

How this conversion works

Wh = mAh × V ÷ 1,000 · kWh = Wh ÷ 1,000 · mWh = Wh × 1,000 · mAh = Wh × 1,000 ÷ V.

mAh, Wh and kWh

Milliamp-hours describe charge; watt-hours and kilowatt-hours describe energy. To convert between them you need the voltage the mAh figure refers to. Phone batteries and power banks quote mAh at the lithium-ion cell voltage — normally 3.6–3.85 V — which is why a “20,000 mAh” power bank holds about 74 Wh, not 100 Wh at the 5 V USB port. Conversion losses mean it delivers roughly 60–70% of that to your phone.

Flying with power banks

The FAA rates lithium batteries by watt-hours: spare lithium-ion batteries and power banks up to 100 Wh are allowed in carry-on baggage, and 101–160 Wh need airline approval, with a limit of two. Spare batteries must not go in checked bags. Airlines can apply stricter rules.

Power bank mAh to Wh chart

Power bank	Wh at 3.6 V	Wh at 3.7 V	Wh at 3.85 V	Carry-on (3.7 V)
5,000 mAh	18.0 Wh	18.5 Wh	19.2 Wh	OK
10,000 mAh	36.0 Wh	37.0 Wh	38.5 Wh	OK
20,000 mAh	72.0 Wh	74.0 Wh	77.0 Wh	OK
25,600 mAh	92.2 Wh	94.7 Wh	98.6 Wh	OK
26,800 mAh	96.5 Wh	99.2 Wh	103.2 Wh	OK
30,000 mAh	108.0 Wh	111.0 Wh	115.5 Wh	Airline approval
40,000 mAh	144.0 Wh	148.0 Wh	154.0 Wh	Airline approval
50,000 mAh	180.0 Wh	185.0 Wh	192.5 Wh	Over 160 Wh: ask airline

kWh and Wh to mAh

Energy	mAh at 3.7 V	mAh at 5 V	mAh at 12 V
1 mWh	0 mAh	0 mAh	0 mAh
1 Wh	270 mAh	200 mAh	83 mAh
10 Wh	2,703 mAh	2,000 mAh	833 mAh
100 Wh	27,027 mAh	20,000 mAh	8,333 mAh
0.5 kWh	135,135 mAh	100,000 mAh	41,667 mAh
1 kWh	270,270 mAh	200,000 mAh	83,333 mAh

Frequently asked questions

How do I convert mAh to Wh?

Multiply mAh by the voltage and divide by 1,000. 10,000 mAh at 3.7 V = 37 Wh.

How many Wh is a 20,000 mAh power bank?

About 74 Wh at the usual 3.7 V cell voltage (72 Wh at 3.6 V, 77 Wh at 3.85 V). That is under the 100 Wh carry-on limit.

Can I take a 30,000 mAh power bank on a plane?

At 3.7 V it is about 111 Wh, which falls in the 101–160 Wh band that needs airline approval. Check the Wh printed on the bank and ask your airline before you fly.

How many mAh is 1 kWh?

It depends on voltage: about 270,000 mAh at 3.7 V, 200,000 mAh at 5 V and 83,333 mAh at 12 V.

Why is my power bank's output less than its mAh rating?

The rating is at the internal 3.7 V cell voltage. Boosting to 5 V or higher and charging the phone's own battery loses energy, so expect about 60–70% of the rated Wh to reach your device.

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Sources & standards

Energy conversions follow SI unit definitions; the carry-on limits come from the U.S. Federal Aviation Administration.

NIST Special Publication 811 — Guide for the Use of the International System of Units (SI) — National Institute of Standards and Technology
Defines the watt, watt-hour, ampere and the conversion factors used on this page.
PackSafe — Lithium Batteries — Federal Aviation Administration
Source of the 100 Wh and 101–160 Wh carry-on limits for spare lithium-ion batteries and power banks, and the Wh = V × Ah method.