Faraday's Law of Electrolysis Calculator
Faraday's laws of electrolysis link the electric charge passed through a solution to the mass of substance deposited or dissolved at an electrode. Enter the current, time, molar mass and ionic charge (valence) to calculate the result.
A
s
g/mol
e⁻
Faraday's first and second laws: m = (M × I × t) / (z × F)
- 1
Total charge Q = I × t
2 A × 3,600 s = 7,200 C - 2
Moles of electrons Q ÷ F
7,200 ÷ 96 485 = 0.074623 molF = 96 485 C/mol is the charge of one mole of electrons (Faraday constant). - 3
Moles of substance ÷ z
0.074623 ÷ 2 = 0.037311 mol - 4
Mass deposited m = n × M
0.037311 × 63.55 = 2.3711
How does this calculator work?
Faraday's electrolysis formula m = (M × I × t) / (z × F) gives mass in grams from current I (A), time t (s), molar mass M (g/mol), ionic charge z, and the Faraday constant F = 96 485 C/mol. Assumes 100% current efficiency; multiply by actual efficiency for real cells.
Formula
How this is calculated
Faraday's first law states that the mass of substance produced at an electrode is proportional to the total electric charge passed: Q = I × t (coulombs = amperes × seconds). Faraday's second law states that the mass also depends on the molar mass of the substance and the number of electrons per ion (the valence z): m = Q × M / (z × F), where F = 96 485.332 C/mol is the Faraday constant — the charge of one mole of electrons.
The formula can be understood step by step: total charge Q = I × t gives the coulombs passed. Dividing by F gives the moles of electrons transferred. Dividing further by z gives the moles of substance deposited or dissolved (since each ion requires z electrons). Multiplying by the molar mass M converts moles to grams.
This calculation applies to electroplating (depositing metal), electrolytic refining, chlorine production, and hydrogen/oxygen generation by water electrolysis. It assumes 100% current efficiency (no competing side reactions). Real cells have current efficiencies below 100%, so actual yields are lower; multiply the result by the cell's current efficiency fraction when known.
Frequently asked questions
The Faraday constant F = 96 485.332 C/mol is the total electric charge carried by one mole of electrons (Avogadro's number × elementary charge). It is an exact SI-defined value since the 2019 redefinition of the SI system.
The valence z is the number of electrons each ion must gain or lose to become neutral. Copper ions Cu²⁺ need 2 electrons (z = 2); silver ions Ag⁺ need 1 (z = 1); aluminium ions Al³⁺ need 3 (z = 3).
Multiply hours by 3 600 to get seconds (1 h = 3 600 s). For example, 2 hours of electrolysis = 7 200 s; enter 7200 in the time field.
Also known as
TG we-Calculate Editorial Team. (2026). Faraday's Law of Electrolysis Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/faraday-calculator
TG we-Calculate Editorial Team. "Faraday's Law of Electrolysis Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/faraday-calculator.
TG we-Calculate Editorial Team, "Faraday's Law of Electrolysis Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/faraday-calculator
@misc{wecalculate_faraday_calculator, title = {Faraday's Law of Electrolysis Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/faraday-calculator}}, year = {2026}, note = {TG we-Calculate} }
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