Electroplating Thickness and Time Calculator Using Faraday's Law
This calculator applies Faraday's law of electrolysis to tell you how long a load must stay in the plating tank to reach a target thickness. It also returns the amps, amp-hours and metal weight the load will consume, which is what you need for rectifier sizing and cost.
Your numbers
Nickel 58.69, copper 63.55, zinc 65.38, tin 118.71, silver 107.87. See the electrochemical reference table.
Nickel, copper, zinc, cadmium 2. Silver and gold (cyanide) 1. Hexavalent chrome 6.
Nickel 8.9, copper 8.96, zinc 7.14, tin 7.31. Real deposits can run a little lower.
1 A/dm2 is about 9.3 A/ft2 (ASF).
Watts nickel and acid copper run 95 to 98 percent. Hard chrome is often 10 to 15 percent.
25 um is about 0.001 inch.
Your results
Faraday's law gives an average thickness. Actual distribution varies with part geometry, rack position and bath conditions, so low-current areas will plate thinner. Confirm with a thickness measurement (XRF or coulometric) before releasing production.
Plating time (minutes) vs current density
Sweeps Cathode current density from 0.5 to 10, holding your other inputs fixed.
Plating routing review
Want plating times and costs pulled straight from your ERP routings? We can walk through how that works on your own data.
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How to use the calculator
Enter the atomic weight, valence and density of the metal you are depositing, then your cathode current density and measured cathode efficiency. Enter the target thickness, the plated area per part and the parts per load. Read plating time first, then total amps to confirm the rectifier can supply the load, and the deposited mass for anode and metal cost. The chart shows how plating time falls as you raise current density, so you can see the payoff of running closer to the top of the bath's recommended range.
- Use area in square decimeters; 1 square foot is 9.29 dm2
- Use measured cathode efficiency from a coulometer or bath records if you have it
- Add rack and wire area to the load current, not just part area
- Treat the result as the in-tank time, then add handling time for scheduling
The formula behind it
Mass deposited per ampere-hour equals atomic weight divided by (valence x 26.801), because one mole of electrons carries 26.801 ampere-hours (96,485 coulombs). Multiply by current density and cathode efficiency to get grams per square decimeter per hour. Divide by density and scale units to get thickness in micrometers. For nickel at 3 A/dm2 and 95 percent efficiency the rate is roughly 0.58 um per minute, so a 25 um deposit takes about 43 minutes. This matches common shop rules of thumb of about 35 um per hour per 3 A/dm2 for Watts nickel.
Reading the results and where it differs from the floor
Average thickness is not minimum thickness. High-current-density edges and corners plate heavier, recessed areas lighter, so specifications that call for a minimum thickness at a significant surface usually need extra time or better anode placement. Cathode efficiency also drifts with bath age, temperature and organic contamination. If measured thickness is consistently below the calculation, check efficiency first, then contact resistance on racks, then current density being applied to the wrong area.
Common mistakes
The most frequent errors are using the wrong valence for the bath chemistry, forgetting cathode efficiency on low-efficiency baths like chrome, and mixing square feet with square decimeters. Another is counting only the part area while the racks, contacts and thieves also draw current, so the rectifier shows a higher amperage than expected. Always compare the calculated amperage to the rectifier rating with at least 20 percent headroom.
Frequently Asked Questions
What is the formula for plating time?
Time in hours equals thickness times density divided by (100 x current density x electrochemical equivalent x efficiency), with thickness in micrometers, density in g/cm3 and current density in A/dm2. The calculator does the unit conversions for you and returns minutes.
What cathode efficiency should I use?
Use your measured value when you have one. Typical ranges are 95 to 98 percent for Watts nickel and acid copper, 90 to 98 percent for acid zinc, and 10 to 15 percent for hexavalent hard chrome. Cyanide baths vary widely with free cyanide and temperature.
Does this work for electroless nickel?
No. Electroless plating is autocatalytic with no external current, so deposition rate is set by bath chemistry, temperature and pH, commonly in the 10 to 25 um per hour range depending on the formulation. Use the supplier's rate data instead.
Why is my measured thickness lower than calculated?
Faraday's law assumes uniform current density. In practice parts have low-current areas, racks absorb current, and efficiency falls as the bath ages. Measure at a defined location and compare it with a calculated value for the same current density at that location.
If plating routings and times live in your ERP, we can help pull part area, thickness and process data into a quoting and scheduling assistant that runs on your own servers.
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