Case 1
- Energy
- 50Wh
- Nominal voltage
- 3.7V
13,514mAh
Open with these valuesWh to mAh Calculator
13,514mAh
Result: 13,514 mAhMultiply the watt-hours by 1000 and divide by the nominal voltage. A 50 Wh pack at 3.7 V holds about 13,514 mAh. The label on a power bank gives mAh, while airline rules and spec sheets give watt-hours — this is the way back.
Worked examples
Case 2
- Energy
- 100Wh
- Nominal voltage
- 12V
8,333mAh
Open with these valuesCase 3
- Energy
- 37Wh
- Nominal voltage
- 3.7V
10,000mAh
Open with these valuesHow it's calculated
mAh = (Wh × 1000) ÷ V
- StepEnter the watt-hour rating from the spec sheet or the battery label.
- StepEnter the nominal voltage — about 3.7 V for one Li-ion cell.
- ResultRead the charge capacity in mAh and compare it with the printed figure.
Reference table
| Energy, voltage | Battery | Capacity |
|---|---|---|
| 0, 3.7 | Nothing stored | 0 |
| 10, 5 | Small USB pack | 2000 |
| 18.5, 3.7 | Compact phone power bank | 5000 |
| 100, 12 | Twelve-volt leisure battery | 8333.33 |
| 37, 3.7 | Standard phone power bank | 10000 |
| 50, 3.7 | Large power bank | 13513.51 |
Questions
How do I convert Wh to mAh?
Multiply the energy in watt-hours by 1000 and divide by the nominal voltage: mAh = (Wh × 1000) ÷ V. A 50 Wh power bank at 3.7 V holds (50 × 1000) ÷ 3.7 ≈ 13,514 mAh.
Why do I need the voltage for this?
Watt-hours measure energy, which is charge times voltage. Without the voltage you cannot separate the two, so the same Wh figure maps to very different mAh values depending on the cell count.
What voltage should I enter for a power bank?
The nominal cell voltage, about 3.7 V for lithium-ion. Power banks are usually rated at the cell voltage even though their USB output is 5 V, so 3.7 V normally reproduces the mAh figure printed on the casing.
When would I need this conversion?
Airline rules and spec sheets state limits in watt-hours, while the number on the power bank is in mAh. Converting lets you check that the two match — or work out the capacity of a battery whose data sheet only lists Wh.
Can I compare two batteries by mAh alone?
Only when their nominal voltages match. A 10,000 mAh pack at 7.4 V stores twice the energy of a 10,000 mAh pack at 3.7 V. For anything across voltages, compare watt-hours instead.
Sources and last check
Information, not professional advice.