A drawing says "zinc plate, clear passivate" in the corner block, and most quotes turn that into a round number — "add a fiver for plating." Sometimes that covers it. Just as often it does not, because electroplating cost is driven by things that have nothing to do with the part price: the surface area being coated, the plating thickness called out in microns, which metal goes in the bath, and how many parts share the same load. A small bracket and a large weldment can weigh the same and cost wildly different amounts to plate. Quote plating as a percentage of the machining bill and you will overprice the big simple parts and lose money on every small one.

This guide breaks a plating line item into the inputs you can actually measure — metal type, surface area, thickness, barrel versus rack handling, masking, and post-plate steps — and shows how to price zinc, nickel, and chrome into a quote you can defend instead of a guess you hope covers it.

Why plating is priced unlike machining

Machining cost scales with how long the spindle runs. Electroplating cost scales with three things that have nothing to do with cycle time: the surface area being coated, the deposit thickness called out on the print, and the load the parts ride in. A bath deposits metal onto a surface at a rate set by current and time, so a thicker deposit literally takes longer in the tank and uses more metal. The plater prices the same way the bath behaves — by area, by thickness, and by batch — floored by a minimum charge per lot.

That makes plating cost behave backwards from machining intuition. A large, simple plate has a lot of surface area and costs more to plate than a small, intricate part that took far longer to machine. And a single prototype can cost the same to plate as fifty parts, because the minimum lot charge is the same whether the barrel is full or nearly empty. This is the same fixed-cost-over-quantity discipline that governs setup and programming in how to price CNC machined parts — and it applies just as hard to outsourced plating as it does to in-house setup.

The three metals and what they cost

Zinc, nickel, and chrome are not interchangeable, and the price gaps between them are large. The metal itself sets the per-area rate, but the bigger driver is what the finish is for — sacrificial corrosion protection, decorative shine, or wear resistance — because that determines thickness, layering, and post-processing. Treat the ranges below as typical and approximate; calibrate against your own plater's price list.

Plating type	Typical use	Typical thickness	Relative cost/area	Notes
Zinc (+ passivate)	Sacrificial corrosion protection on steel	5–25 µm	Baseline (cheapest)	Usually barrel; clear/yellow/black chromate adds a step
Nickel (electrolytic)	Decorative + corrosion, undercoat for chrome	10–40 µm	~2–4× zinc	Nickel metal is expensive; bright vs satin
Decorative chrome	Bright cosmetic finish over nickel	~0.2–0.5 µm chrome over nickel	~3–5× zinc	Thin chrome flash; cost is mostly the nickel underneath
Hard chrome	Wear, hardness, build-up of worn parts	25–250+ µm	Highest	Thick, slow, often ground after plating

The classic estimating trap is reading "chrome" on a drawing and picturing one process. Decorative chrome is a whisper-thin flash over a nickel layer — most of its cost is the nickel. Hard chrome is a thick, slow, engineering deposit that is frequently ground back to size afterward, which is a second machining operation nobody costed. Quote one at the other's rate and the difference comes straight out of margin. Read the spec, not the word.

Barrel vs rack: the decision that sets your labour

The single biggest labour swing in plating is how the parts are loaded. Barrel plating tumbles many small parts together in a rotating drum — almost no per-part handling, very cheap, but unsuitable for anything that tangles, scratches easily, or needs even coverage on a critical face. Rack plating hangs each part individually on a fixture so it plates evenly and comes out unmarked — far better finish, but every part is handled by hand, which is real labour the plater charges for.

The rule of thumb: small, robust, high-volume parts go on the barrel and are cheap per piece; large, delicate, cosmetic, or tight-tolerance parts go on a rack and cost several times more to handle. If a drawing's finish callout or a critical surface forces rack plating on a part you assumed would barrel, your plating line can double. Cost the handling at a fully burdened line rate the same way you would a machine hour — see how to build a fully burdened shop rate — rather than waving it off as "cheap."

Building the plating line: a formula

You do not need a CAD surface-area readout to the square millimetre — a reasonable estimate of coated area is enough, because the lot minimum usually governs on small batches anyway. Build the batch cost like this:

1. Estimate the coated surface area of one part (sum the major faces, in dm² or ft²).
2. Multiply by quantity to get the batch area.
3. Multiply batch area by the plater's per-area rate for that metal and thickness.
4. Add handling (barrel load vs per-part racking), masking labour, and any post-plate step (passivation colour, embrittlement bake).
5. Compare the total to the lot minimum and take the higher of the two.
6. Divide by quantity for the per-part number you fold into the quote.

Step 5 is the one hand-built quotes skip, and it is the one that loses money. Spread a typical €70–€150 lot minimum across the batch and the per-part finishing cost swings wildly with quantity:

Batch size	Lot minimum	Plating cost per part
1	€90	€90.00
10	€90	€9.00
50	€90	€1.80
200	€90	€0.45 (or per-area rate, if higher)

A single plated prototype that you quoted with the two-hundred-off finishing cost loses you the difference on every order.

The callouts that quietly add cost

Three details on the print turn a clean plating line into a more expensive one, and each is easy to miss on a fast read.

Post-plate passivation and colour. Zinc is almost always followed by a chromate conversion — clear, yellow (iridescent), or black — which adds corrosion resistance and a step the plater charges for. A "zinc, yellow passivate" callout is not the same price as bare zinc, and black chromate is usually dearer again.

Hydrogen embrittlement relief. High-strength steel (typically above ~1000 MPa / 32 HRC — fasteners, springs, hardened parts) absorbs hydrogen during plating and can crack later under load. The spec will call for a post-plate bake (commonly 190–220 °C for several hours) to drive it out. That bake is oven time, energy, and a handling step — a real cost line, and a safety-critical one you must not silently drop. The same goes for tight-tolerance features where the deposit thickness eats the fit; that is exactly the kind of callout to catch alongside the dimensions, as covered in G&D&T and tolerances for estimators.

Masking and RoHS chrome. Threaded holes, bearing bores, and electrical contact points that must stay bare are masked by hand — per-part labour that scales with the number of features. And on chrome, the regulatory shift from hexavalent to trivalent chrome (RoHS/REACH-driven) changes the bath, the colour, and the price; quoting from an old hex-chrome rate can misprice the job. Read which chemistry the customer actually requires.

Outsourcing, markup, and lead time

For most small and mid-size shops, plating is sent out, and that changes two things in the quote. First, the cost is a vendor invoice, not a burdened hour — and you should mark it up like any bought-in service, not pass it through at cost, because you carry the handling, freight both ways, the quality risk, and the cash-flow gap. Decide that markup deliberately the same way you set margin elsewhere; the difference between margin and markup, and how to apply each, is laid out in margin vs markup in manufacturing pricing.

Second, outsourced plating adds calendar days — typically two to five working days plus transit, more if a bake or a second machining op follows hard chrome — and that has to land in your promised lead time, not just your price. A part that machines in a day but waits a week at the plater is a one-week part; manufacturing lead-time estimation covers how to fold outside-process queue time into the date you quote. Either way, the plating cost belongs as its own line on the quote, not buried in a finishing percentage — a clear line item is part of what makes a quote readable and defendable, which is the whole point of a consistent manufacturing quote template.

From drawing to a plating-inclusive quote

The slow, error-prone part of quoting plated parts is the reading: catching the finish callout, telling decorative chrome from hard chrome, spotting the passivation colour, noticing the high-strength steel that needs an embrittlement bake, seeing which holes are masked, and estimating the coated area — all before you reach the plater's price list. Under deadline pressure that reading gets shortcut, and the plating line becomes a round-number guess.

QuoteBuddy reads the technical drawing and surfaces the inputs a plating line needs — material, finish and thickness callouts, masked features, tolerances, and geometry — so the estimator works from a complete picture instead of a hurried scan. The cost engine then builds finishing as its own line, by metal, area, thickness, handling, and your vendor markup, the same way every time, so two estimators quoting the same part land on the same number. The AI handles the reading; your rules handle the pricing.

Start a 30-day trial and run a few real plated drawings through the process — from upload to a complete, itemised quote. See whether the plating cost it builds matches what you would have quoted by feel, and where the "add a fiver for plating" was quietly costing you on every small batch.