How to use this calculator
- Enter coated area. Use total developed surface area for every part in the batch, including both sides and formed faces.
- Set dry film thickness and powder SG. Use the coating specification and powder technical data sheet when available.
- Enter booth efficiency assumptions. Enter first-pass transfer efficiency, reclaim efficiency and setup waste separately.
- Check coverage and pounds to plan. Compare theoretical coverage with actual coverage, then use powder-to-plan and material cost for the batch estimate.
How it works
Powder coverage starts with the ideal dry film volume:
Vfilm = A x t
where A is coated area and t is cured dry film
thickness. Powder density is estimated from specific gravity:
rho = SG x 1000 kg/m3
so the powder locked into the dry film is:
mfilm = A x t x rho
Transfer efficiency accounts for first-pass powder that actually reaches
the part:
msprayed = mfilm / eta transfer
Overspray is msprayed - mfilm. If the booth reclaims part of
that overspray, the net fresh powder is:
mnet = msprayed - (msprayed - mfilm) x eta reclaim
The final planning number adds setup, purge, cleanup and small-batch waste:
mplan = mnet x (1 + waste)
The shortcut many shops use for theoretical imperial coverage is: coverage ft2/lb = 192.3 / (SG x film thickness in mil) The actual coverage output is lower because it includes transfer loss, reclaim and setup waste. Pair this with the sheet-metal box flat pattern calculator, cone flat pattern calculator, duct transition calculator, metal weight calculator and machine shop rate calculator.
Worked example
Verified against the live calculator
For 500 ft2 of coated area at 3 mil dry film with
SG 1.5, the theoretical coverage is about
42.7 ft2/lb. At 65% transfer efficiency, no reclaim
and 10% setup waste, plan about 19.8 lb of powder.
At $8/lb, the powder material cost is about $158.
Frequently asked questions
How do you calculate powder coating coverage?
Start with dry film volume: coated area times cured film thickness. Multiply by powder density, using specific gravity times 1000 kg/m3, to get the ideal dry film powder mass. Then divide by transfer efficiency and apply reclaim and setup waste.
What transfer efficiency should I use?
Use measured booth data when you have it. A simple batch booth or complex part may be much lower than 60%, while optimized electrostatic setups can be higher. Do not mix reclaim into the transfer-efficiency number; this calculator has a separate reclaim input.
Does this include reclaimed powder?
Yes. Reclaim is applied to overspray only: sprayed powder minus powder that reached the dry film. Set reclaim to 0% for color-change work, non-reclaim booths or when recovered powder is not reused on the same job.
Is this a powder coating quote calculator?
It is only a powder material and coverage screen. A finished quote still needs pretreatment, masking, labor, racks, cure schedule, utilities, rejects, minimum orders, packaging and freight.
Method & assumptions
- Area is total coated surface area for the full batch, not floor area or one-sided blank area unless that is the true coated area.
- Specific gravity is treated as powder density relative to water; use the powder data sheet when possible.
- Transfer efficiency is first-pass powder on the part. Reclaim is applied only to overspray.
- Setup waste is applied after transfer and reclaim to cover purge, hose/gun setup, booth cleanup, rejects and handling loss.
- This does not check pretreatment, coating compatibility, cure schedule, film build limits, edge coverage, Faraday-cage effects, grounding, masking, labor or shop pricing.