Battery capacity converter
Convert mAh to Wh and back. Pick the voltage first: the same 5,000 mAh is 18.5 Wh in a phone and 60 Wh at 12 V.
That's 1.23× as big as a phone battery, while a 10,000 mAh power bank is 2× bigger. That is about 1.233 full phone charges.
What it means
How much energy is that?
Airlines limit spare batteries to 100 Wh without approval, which is why the Wh figure matters.
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Learn
Three things worth knowing
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Wh = mAh × V ÷ 1000
A 5,000 mAh phone cell at 3.7 V holds 18.5 Wh. The same number of mAh at 12 V holds 60 Wh, three times as much energy.
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Why power banks lie a little
A 10,000 mAh bank is measured at its internal 3.7 V, but charges your phone at 5 V. After conversion losses you get about 6,000 mAh into the phone, and nothing is faulty.
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mAh across voltages means nothing
Comparing a 3.7 V phone cell with a 48 V e-bike pack by mAh is meaningless. Convert both to watt-hours first, then compare.
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Background
About battery units
mAh counts charge, not energy. To get energy you multiply by the voltage: Wh = mAh × V ÷ 1000. That is why a 10,000 mAh power bank is 37 Wh, not 10 kWh.
Comparing two batteries by mAh alone only works if they run at the same voltage.