mAh to Wh Converter
Quick fact: To convert milliamp-hours to watt-hours, multiply mAh by voltage and divide by 1,000. A 5,000 mAh Li-ion battery (3.7V) stores 18.5 Wh of energy.
Frequently Asked Questions
What is the difference between mAh and Wh?
mAh (milliamp-hours) measures electric charge capacity — how much current a battery can deliver over time. Wh (watt-hours) measures energy — the total amount of work the battery can perform.
The relationship is: Wh = mAh × V / 1,000. Two batteries with the same mAh but different voltages store different amounts of energy. A 3,000 mAh battery at 3.7V stores 11.1 Wh, while the same 3,000 mAh at 7.4V stores 22.2 Wh.
How do I convert mAh to Wh?
Multiply the mAh rating by the battery voltage, then divide by 1,000:
Wh = mAh × V / 1,000
Example: A 5,000 mAh power bank at 3.7V: 5,000 × 3.7 / 1,000 = 18.5 Wh.
Why do airlines use Wh instead of mAh?
FAA and IATA regulations limit lithium batteries to 100 Wh for carry-on luggage (160 Wh with airline approval). Wh is used because it accounts for voltage, making it a fairer measure of total stored energy regardless of battery configuration.
A 27,000 mAh power bank at 3.7V = 99.9 Wh (allowed). The same 27,000 mAh at 7.4V = 199.8 Wh (prohibited).
What is the Wh of a typical phone battery?
Most smartphone batteries are 3.7V Li-ion cells:
- 4,000 mAh phone battery: 4,000 × 3.7 / 1,000 = 14.8 Wh
- 5,000 mAh phone battery: 5,000 × 3.7 / 1,000 = 18.5 Wh
Both are well under the 100 Wh airline limit for carry-on batteries.
How to Convert mAh to Wh
Converting milliamp-hours to watt-hours requires knowing the battery voltage:
- Find the battery voltage. Check the battery label for the nominal voltage. Common values: 1.2V (NiMH), 1.5V (Alkaline), 3.7V (Li-ion), 3.2V (LiFePO4), 12V (Lead-acid).
- Apply the formula: Wh = mAh × V / 1,000
- Example: A 10,000 mAh power bank at 3.7V: 10,000 × 3.7 / 1,000 = 37 Wh.
mAh to Wh Formula
Where:
- Wh = watt-hours (energy)
- mAh = milliamp-hours (charge capacity)
- V = nominal battery voltage (volts)
This formula works because: Wh = Ah × V, and mAh / 1,000 = Ah. So Wh = (mAh / 1,000) × V = mAh × V / 1,000.
Common Battery Types: mAh to Wh Reference
| Battery Type | Typical mAh | Voltage | Wh |
|---|---|---|---|
| AA NiMH | 2,500 | 1.2V | 3 Wh |
| AA Alkaline | 2,800 | 1.5V | 4.2 Wh |
| AAA NiMH | 1,000 | 1.2V | 1.2 Wh |
| 18650 Li-ion | 3,500 | 3.7V | 12.95 Wh |
| Smartphone | 4,000–5,000 | 3.7V | 14.8–18.5 Wh |
| Power bank (small) | 10,000 | 3.7V | 37 Wh |
| Power bank (large) | 26,800 | 3.7V | 99.16 Wh |
| Laptop battery | 5,000–8,000 | 11.1V | 55.5–88.8 Wh |
| Drone battery | 5,000 | 11.1V | 55.5 Wh |
| Car battery (12V) | 50,000 | 12V | 600 Wh |
mAh vs Wh: Key Differences
| Property | mAh | Wh |
|---|---|---|
| Full name | Milliamp-hours | Watt-hours |
| Measures | Electric charge (capacity) | Energy (total work) |
| Depends on voltage? | No | Yes |
| Used for | Phone batteries, power banks | Laptops, drones, airline regulations |
| Comparable across voltages? | No | Yes |
Airline Battery Limits (FAA / IATA)
When traveling by air, lithium battery limits are measured in Wh, not mAh:
- Under 100 Wh (up to ~27,000 mAh at 3.7V) — allowed in carry-on, no approval needed
- 100–160 Wh (~27,000–43,200 mAh at 3.7V) — carry-on only, requires airline approval
- Over 160 Wh — prohibited on passenger aircraft
Use this converter to check if your battery meets airline requirements before flying.
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Formula: Wh = mAh × V / 1,000. Results assume nominal battery voltage.
