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How much does anodize add to a dimension?

Last updated 10 August 2026

About half of it. An anodize call-out states total coat thickness, and roughly half of that grows into the base metal rather than out from it.

This is the difference between anodize and plating and it catches shops that treat the two the same way. Plating deposits material on top of the surface. Anodizing converts aluminum at the surface into oxide, which occupies more volume than the metal it replaced, so the coat grows in both directions from the original profile.

Walk an anodize specification back the way you would walk a plating specification and you leave twice the correction the part needed. The resulting number is wrong and entirely plausible, which is why it survives a review.

Worked

On the print	.4990 / .5010 in
Process	Anodize
Per side	0.0004 in
The dimension gets	larger at this operation
Pitch diameter shift per unit of per-side effect	2 times
Hold before the process	.4986 / .5006 in

The process window is a single value, so the band shifts without narrowing.
This call-out states total coat thickness and only about half of it sits above the base metal, so the effective correction is halved. Treating it like a plating spec leaves twice the stock needed.

Open this case in the calculator, and change the numbers.

Computed by ctrlPlanner. MIL-STD-870, Federal Screw Thread Specification H28.