rafhleðsla, Q: Q = I · t, (t = sekúndur); [electronic charge].

Grunnhleðsla rafeindar [electronic charge] er 1,60217733 · 10⁻¹⁹ C (coulomb).

1  coulomb samsvarar 6,24 · 10¹⁸ rafeindum (e^-).