Plating time calculator.
Tank time, deposition rate, current draw, and metal consumed for eleven plating baths.
Set the bath and the target
Every bath, and what one thousandth of an inch takes
The constants are physics. The efficiency column gives the conventional starting figure for each bath, and it is the one that moves. Because efficiency divides into the time, halving it doubles the plating time, so a measured figure from your own line is better than any number in this column.
| Bath | Molar mass | Valence | Density | Efficiency | Typical ASF | At ASF | Time for 0.001" |
|---|---|---|---|---|---|---|---|
| Nickel, Watts bath | 58.69 | 2 | 8.90 | 95% | 30 to 60 | 45 | 27 min |
| Nickel, sulfamate | 58.69 | 2 | 8.90 | 98% | 30 to 100 | 65 | 18 min |
| Copper, acid sulfate | 63.55 | 2 | 8.96 | 97% | 20 to 50 | 35 | 32 min |
| Copper, cyanide strike | 63.55 | 1 | 8.96 | 60% | 10 to 30 | 20 | 45 min |
| Zinc, acid chloride | 65.38 | 2 | 7.14 | 95% | 15 to 40 | 28 | 31 min |
| Zinc, alkaline non-cyanide | 65.38 | 2 | 7.14 | 80% | 10 to 30 | 20 | 52 min |
| Chromium, hexavalent | 52.00 | 6 | 7.19 | 15% | 100 to 400 | 250 | 84 min |
| Tin, acid sulfate | 118.71 | 2 | 7.29 | 95% | 10 to 40 | 25 | 20 min |
| Silver, cyanide | 107.87 | 1 | 10.49 | 98% | 5 to 20 | 13 | 29 min |
| Gold, cyanide | 196.97 | 1 | 19.32 | 60% | 2 to 10 | 6 | 103 min |
| Cadmium, cyanide | 112.41 | 2 | 8.65 | 90% | 15 to 40 | 28 | 23 min |
What each bath does differently
- Nickel, Watts bath. The arithmetic gives roughly one thousandth of an inch in half an hour at 40 ASF, which is the rule of thumb most nickel lines run on.
- Nickel, sulfamate. Low stress deposit used for engineering thicknesses and electroforming.
- Copper, cyanide strike. Copper is monovalent in a cyanide bath, so the same charge deposits twice the metal an acid bath would.
- Zinc, alkaline non-cyanide. Better distribution than acid zinc and lower efficiency, which is the trade the process exists to make.
- Chromium, hexavalent. Six electrons per atom and an efficiency between roughly 10% and 25% make this the least predictable entry here. Use a measured efficiency for your own bath.
- Gold, cyanide. Efficiency varies widely with bath chemistry and is worth measuring, since the metal is the cost.
- Cadmium, cyanide. Restricted in many applications. Included because aerospace and defense specifications still call for it.
Thickness conversions worth keeping straight
| Microns | Inches | Microinches | Where it turns up |
|---|---|---|---|
| 1.3 | 0.00005 | 50 | Decorative flash, gold contacts |
| 2.5 | 0.0001 | 100 | Light decorative deposits |
| 5 | 0.0002 | 200 | Commercial zinc, mild service |
| 8 | 0.0003 | 300 | Common zinc callout for fasteners |
| 12.7 | 0.0005 | 500 | Heavier zinc, general nickel |
| 25.4 | 0.0010 | 1000 | Engineering nickel, light hard chrome |
| 127 | 0.0050 | 5000 | Hard chrome for wear, salvage work |
Questions platers ask about plating time
How do you calculate electroplating time?
Rearrange Faraday’s law to solve for time. Plating time in seconds equals the thickness in centimeters times the deposit density times the valence times the Faraday constant, all divided by the current density in amps per square centimeter times the molar mass times the cathode efficiency. Every term except efficiency is a physical constant, so efficiency is the number worth measuring on your own bath.
How long does it take to plate one thousandth of an inch of nickel?
About 30 minutes at 40 amps per square foot and 95 percent cathode efficiency, which matches the rule of thumb most Watts nickel lines run on. Raising the current density shortens it proportionally, so 80 amps per square foot halves the time, until burning and poor distribution set the practical limit.
What is cathode efficiency and why does it matter so much?
Cathode efficiency is the fraction of the current that actually deposits metal, with the rest generating hydrogen. A Watts nickel bath runs near 95 percent, so almost all the current does useful work. Hexavalent chromium runs between roughly 10 and 25 percent, so most of the current makes gas. Because efficiency divides into the time, halving it doubles the plating time, which makes it the largest single source of error in any predicted figure.
Why does chromium take so much longer than nickel?
Chromium takes longer for two reasons that multiply together. It deposits from a hexavalent bath needing six electrons per atom against nickel’s two, and its cathode efficiency is a fraction of nickel’s. The combination means a chromium bath needs several times the charge for the same thickness, which is why hard chrome lines run at very high current densities and still take hours.
Does this predict the thickness on edges and in recesses?
No, and no arithmetic can. The calculator gives an average thickness at the current density you entered. Real deposits are thicker on edges and corners where the field concentrates, and thinner in recesses and on inside surfaces. Racking, shielding, thieves and anode placement decide the distribution. The only reliable check is a thickness measurement on the part, in the places the specification cares about.
Does it work for electroless nickel?
No. Electroless processes deposit by chemical reduction with no current flowing, so Faraday’s law does not apply at all. An electroless nickel bath deposits at a rate set by its chemistry, its temperature and its age, conventionally quoted in microns per hour and typically in the region of 10 to 25. Take the rate from the bath supplier and from your own logs.
How do I convert between mils, microns and microinches?
One thousandth of an inch, called a mil, is 25.4 microns and 1000 microinches. One micron is 39.37 microinches. Specifications move between all three, and one misplaced decimal is the difference between a passing and a failing coating, so it is worth writing the conversion down each time.
Who made it, and what it does not do
This tool was written by Shopfloor Agency's lead engineer, who holds a bachelor’s degree in mechanical engineering and builds websites for US manufacturers. It runs entirely in your browser.
Faraday’s law is exact, and the constants are physical properties. Cathode efficiency is different: it belongs to your bath on the day, it moves with temperature, additives, age, and part geometry, and it divides straight into the answer. The result is an average thickness at the stated current density, and it cannot show the distribution across a real part. It does not apply to electroless processes, where no current flows. Use it as a planning figure, and measure the part.
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