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Electric charge (Q) is the amount of electricity that flows, measured in coulombs (C). Current is the rate of charge flow, so charge is simply current multiplied by time: one amp flowing for one second moves one coulomb. Batteries are rated in amp-hours (Ah), which is just charge expressed over hours.
| Quantity | Formula / Value |
|---|---|
| Charge | Q = I × t |
| Amp-hour | 1 Ah = 3600 C (1 mAh = 3.6 C) |
| Electrons in a charge | n = Q / e, e = 1.602×10−19 C |
| Runtime from capacity | t = capacity(Ah) / current(A) |
Because one electron carries a tiny 1.602×10−19 C, even a single coulomb is about 6.24×1018 electrons.
Electric charge is the quantity of electricity, measured in coulombs (C). It is the total amount of electrons that have flowed, equal to current multiplied by time.
Q = I × t, where Q is charge in coulombs, I is current in amps, and t is time in seconds. Rearranged, I = Q/t and t = Q/I.
The SI unit of charge. One coulomb is the charge moved by one amp of current flowing for one second, and equals about 6.24×10¹⁸ electrons.
Multiply by 3600, since one hour is 3600 seconds. So 1 Ah = 3600 C and 1 mAh = 3.6 C.
It is the charge the battery can deliver: a 2000 mAh cell can supply 2000 mA for one hour, or 1000 mA for two hours, and so on (ideally).
Divide the capacity by the current: runtime(h) = capacity(Ah) / current(A). A 2 Ah battery at 0.5 A lasts about 4 hours.
About 6.24×10¹⁸, because each electron carries 1.602×10⁻¹⁹ C of charge.
The elementary charge, e = 1.602×10⁻¹⁹ coulombs (negative for an electron, positive for a proton).
No. Current is the rate of charge flow (coulombs per second = amps). Charge is the total amount that has flowed over a time.
Real batteries deliver less at high discharge rates and low temperatures (the Peukert effect), so actual runtime is often shorter than capacity divided by current.
The mass of metal deposited is proportional to the charge passed (Faraday's law), so controlling current and time controls the coating.
Yes — choose the time unit next to the time field and the calculator converts to seconds internally.
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