Compute excess or deficit electrons from net electric charge — and vice versa. Uses the exact elementary charge e = 1,602176634×10−19 C (SI 2019 definition). Runs entirely in your browser, no server.
Number of electrons from charge (n = Q / e)
Charge from electron count (Q = n × e)
Charge unit conversion
Unit
Equivalent value
Verified worked examples
1. Charge −1 µC → how many excess electrons?
n = −10−6 / 1,602176634×10−19 ≈ −6,2415×1012 → 6,24 triliun elektron berlebih.
2. Sisir plastik bermuatan −5 nC
n = −5×10−9 / e ≈ −3,1208×1010 → about 31 billion excess electrons stuck on the comb.
3. Kelebihan 10¹² elektron → muatannya?
Q = n × e = −1012 × 1,602176634×10−19 ≈ −1,6022×10−7 C (−0,1602 µC).
4. Defisit 2,5×10¹² elektron (kation)
Q = +2,5×1012 × e ≈ +4,0054×10−7 C (+0.4005 µC) — positive charge = electron deficit.
Guide: reading results correctly
Konvensi tanda
Elektron bermuatan negatif. Benda netral has electrons = protons. Adding electrons → net charge negatif (excess electrons, anion). Removing electrons → net charge positif (electron deficit, cation). This calculator shows signed n: negative n = excess, positive n = deficit.
Why is e exact?
Since the 2019 SI revision, the elementary charge e = 1,602176634×10⁻¹⁹ C is a defining constant — its value is fixed exactly, not measured, so it has no uncertainty. Its derived factor: 1 C = 6.241509074460763×10¹⁸ electrons (exact in unbounded decimal arithmetic; float64 gives 15–16 correct significant digits).
Batasan model
This model is classical and uses only net charge: it knows nothing of charge distribution, does not distinguish excess protons from missing electrons at particle level (both give positive net charge), and ignores quantum effects. For macroscopic objects, round n to the nearest integer — no half electrons.
Batasan cakupan. This tool computes the number of electrons from charge. For the speed of electrons from kinetic energy (relativistic/non-relativistic), use
the electron speed calculator. For general charge unit conversion (mAh, faradays, Coulomb’s law, capacitors), use
charge-converter.
Educational physics calculator. Results use double-precision floating-point arithmetic (IEEE-754); for precision research, verify with an arbitrary-precision decimal library.
Frequently asked questions
The formula is n = Q / e, with n = number of electrons (signed), Q = net electric charge in coulombs, and e = 1.602176634×10⁻¹⁹ C. Example: a charge of −1 µC contains n = −10⁻⁶ / 1.602176634×10⁻¹⁹ ≈ −6.2415×10¹² electrons, i.e. about 6.24 trillion EXCESS electrons.
e = 1.602176634×10⁻¹⁹ coulombs, and this value is EXACT by definition — since the 2019 SI revision, the elementary charge is a defining constant with no measurement uncertainty. This calculator uses that exact value.
Negative net charge means EXCESS electrons: more electrons than protons (e.g. anions, or a rubbed plastic comb). Positive net charge means an electron DEFICIT: fewer electrons than protons (e.g. cations). Zero charge means neutral.
1 coulomb = 1 / 1.602176634×10⁻¹⁹ ≈ 6.241509074460763×10¹⁸ electrons. This is the reciprocal of the elementary charge and is often used as a quick conversion factor.
Physically, charge is quantized: the number of excess electrons on one object is always an integer (no half electrons). Decimal results in this calculator come from floating-point rounding; for macroscopic objects, round to the nearest integer.
This calculator computes the NUMBER of electrons from net charge (n = Q/e) — electrostatics problems like ‘how many excess electrons on a −2 µC charge’. The electron speed calculator computes electron SPEED from kinetic energy (v from E, classical or relativistic) — particle physics and electron microscope problems. Both use the same electron constants but answer different questions.
The charge converter is a general charge-unit converter (coulombs, mAh, faradays, Coulomb’s law, capacitors) with one info tab on electrons per coulomb. This calculator is a dedicated two-way solver for excess/deficit electron problems: n from Q as well as Q from n, complete with charge-sign interpretation (excess vs deficit) and electrostatics worked examples.
Electrostatics (charge on a rubbed comb, balloon, or glass rod), the Millikan oil-drop experiment that measured the elementary charge, semiconductor physics (doping adds excess electrons / holes as deficit), plus lightning rods and electrostatic precipitators.
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