Mirrorless camera battery: converting mAh to Wh for airline carry-on limits
I packed several spare mirrorless camera batteries for a shoot and only realized at airport security that battery limits are enforced in watt-hours, not the mAh number printed prominently on the battery itself.
We write the way we argue on the bench: exact factor, one sharp trap, one worked example you can re-check.
I packed several spare mirrorless camera batteries for a shoot and only realized at airport security that battery limits are enforced in watt-hours, not the mAh number printed prominently on the battery itself.
I still keep a screenshot of this relationship because memory is where the wrong cousin of a unit sneaks in.
The factor that settles arguments
This is the relationship our converters use. Screenshot it if you have to — just stop re-deriving it from a half-remembered blog post.
Wh = mAh × V ÷ 1,000 — at 7.2V (typical mirrorless battery), 1 mAh = 0.0072 Wh
Write that line once at the top of your notes. Every later arithmetic step should point back to it instead of inventing a friendlier number mid-stream.
The mistake that keeps showing up
Assuming a battery's mAh rating is directly comparable to another battery's Wh limit without converting through the voltage — a high-mAh battery at low voltage might actually be under a Wh threshold, and vice versa.
I still write the unit next to every intermediate value. It looks pedantic until it catches the one swap that would have shipped wrong.
- Write down the known value in mAh (camera battery).
- Confirm the target unit is really Wh, not a similar-looking one.
- Apply the factor: Wh = mAh × V ÷ 1,000 — at 7.2V (typical mirrorless battery), 1 mAh = 0.0072 Wh.
- Round only at the end, to the precision your tool or spec supports.
Worked example
A mirrorless camera battery is rated 2,280 mAh at 7.2V, and airline rules restrict spare batteries by watt-hours.
2280 mAh (camera battery) × 0.0072 = 16.416 Wh
That's 16.416 Wh — round only to the precision your tool or spec actually needs.
I usually convert once, write the answer with units, then convert back. That two-step habit has saved more weekends than any fancy app.
Quick reference table
| mAh (camera battery) | Calculation | Wh |
|---|---|---|
| 1 | 1 × 0.0072 | 0.0072 |
| 2 | 2 × 0.0072 | 0.0144 |
| 5 | 5 × 0.0072 | 0.036 |
| 10 | 10 × 0.0072 | 0.072 |
Use the table for speed once you trust the factor. Do not use it as a substitute for understanding which definition of the unit you are on.
Why the exact number matters
Airlines commonly cap carry-on spare batteries at 100 Wh (with some allowing more with approval) — miscalculating from mAh alone risks a battery being confiscated at the gate.
Precision is not about showing off decimals. It is about making sure the shopping list, the machine setting, and the acceptance check are all describing the same physical quantity.
Pocket recap
Multiply mAh by voltage and divide by 1,000 to get Wh — a 2,280 mAh, 7.2V battery is about 16.4 Wh, comfortably under typical airline limits.
Keep the converter link nearby for the next time the same debate shows up in a group chat. Re-typing the factor from memory is how the wrong cousin of a unit sneaks back in.
Try the converters mentioned in this article
FAQ
What is the exact mAh (camera battery) to Wh factor here?+
Wh = mAh × V ÷ 1,000 — at 7.2V (typical mirrorless battery), 1 mAh = 0.0072 Wh
Should I round partway through the calculation?+
No — carry full precision through the multiplication and round only the final answer, to the precision your tool, gauge, or spec actually supports.
What's the single biggest mistake people make with this conversion?+
Assuming a battery's mAh rating is directly comparable to another battery's Wh limit without converting through the voltage — a high-mAh battery at low voltage might actually be under a Wh threshold, and vice versa.
This article was written by The Turbo Unit Converter engineering desk (Applied units & field metrology) and last reviewed on 2026-07-18 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.