How is electroplating priced? Surface area (dm²) and drawings explained
The answer to “what will plating this part cost?” lies in its surface, not its weight. Plating chemistry, current and time are consumed in proportion to surface area, which is why the industry prices in square decimetres (dm²). This guide shows how dm² is calculated and which other factors move the price.
What is a dm²?
One dm² is a 10 cm × 10 cm square, or 100 cm² (about 15.5 in²). A coffee-table leg typically has 5 to 30 dm² of surface, a cabinet handle 1 to 3 dm². Every square centimetre a part carries into the bath consumes chemistry and energy.
Calculating dm² from a technical drawing
Most furniture metal is made from tube. For tube parts, the outer surface is the total length multiplied by the outer perimeter of the profile:
dm² = total length (cm) × profile perimeter (cm) ÷ 100
- Find the total length. The cutting list on the drawing gives each tube’s length and quantity; multiply and add them up.
- Find the profile perimeter. A 20×20 mm square tube is 2+2+2+2 = 8 cm; 15×15 mm is 6 cm; a Ø25 mm round tube is π × 2.5 ≈ 7.85 cm.
- Multiply and divide by 100. For sheet parts, count both faces: width × length × 2.
Example: a 260 × 750 mm rear table-leg frame made from 2,020 mm of 20×20 tube. 202 cm × 8 cm = 1,616 cm² = 16.2 dm².
What counts for plating is the outer surface. The “surface area” a 3D model reports includes the inside of closed tubes, so it should not be used directly for pricing.
What else moves the price?
| Factor | Effect on price |
|---|---|
| Process steps | Each extra layer (matte nickel, copper, chrome, colour coat) adds chemistry and time; dropping a layer the part does not need lowers the price. |
| Parts per rack | The more parts fit on a rack, the more the labour is shared; large, bulky parts carry more labour per piece. |
| Polishing and surface condition | Weld grinding and polishing are separate labour; parts that arrive finished cost less. |
| Geometry | Deep recesses and closed corners are harder to plate and may need special racking or auxiliary anodes. |
| Batch size | On small batches, set-up and inspection cost weigh more per piece. |
Getting an accurate quote
Sending the drawing with its cutting list makes a quote both faster and more accurate. At Serel Metal, each part’s dm² is calculated from the drawing, parts per rack are set by the racking plan, and the price follows from those figures. We list everything to send in our plating RFQ checklist.
Frequently asked questions
Is plating priced by weight?
Not for decorative furniture plating. Weight-based pricing applies only to very small parts plated in bulk; rack plating is priced by dm².
I have no drawing. How do I find the dm²?
Measure the tube length end to end and tell us the profile size, or send a sample and we will measure it.
Why can two parts with the same dm² cost differently?
Different rack counts, geometry or process steps lead to different prices for the same area.
Want a price for your parts?
Send your drawing; we will calculate the dm² and quote within one business day.