The Car Paint Calculator estimates how much automotive paint to buy for a respray. The quick mode gives rough ready-to-spray amounts of base coat, clear coat and primer by vehicle size and job type. The area mode calculates sprayable paint from the area you’re painting, number of coats, dry film thickness, solids content and spray gun transfer efficiency.
Car Paint Calculator
How much automotive base coat, clear coat and primer to buy for a full respray by vehicle size, or from the area you are painting.
Typical amounts of ready-to-spray material. Check your paint system’s mixing ratio: unmixed quantities are smaller.
Quantities are for mixed, ready-to-spray material. Check your paint system’s technical data sheet and mixing ratio — the unmixed amounts you buy are smaller.
Formula
By vehicle size: base = clear = 1 gal × size factor × job factor; primer = half of that
From area: V = A × coats × dry film ÷ solids ÷ transfer efficiency
Where A = area painted, dry film = thickness per coat (1 mil = 0.001 in), solids = fraction of the sprayed paint that stays as film, and transfer efficiency = fraction that lands on the car.
How the Calculation Works
Step 1: The film you want = area × coats × dry film thickness.
Step 2: Divide by solids — most of the sprayed liquid is solvent that evaporates.
Step 3: Divide by transfer efficiency — overspray never reaches the panel.
Variables Explained
| Vehicle | Size factor |
|---|---|
| Compact / small car | 0.75 |
| Mid-size sedan | 1.0 |
| Full-size car / small SUV | 1.25 |
| Large SUV / pickup | 1.5 |
| Van / large truck | 2.0 |
A color change (door jambs, engine bay) uses a 1.3 job factor. These factors are the calculator’s rough guide.
Example Calculation
By vehicle size
Mid-size sedan, full respray: about 1 gal base, 1 gal clear, 0.5 gal primer (ready to spray)
From area
Given: 180 ft², 3 coats, 0.8 mil dry per coat, 20% solids, 65% transfer efficiency (HVLP)
Film volume = 180 × 144 in² × 3 × 0.0008 in = 62.2 in³
Sprayable = 62.2 ÷ 0.20 ÷ 0.65 ≈ 478.5 in³ ≈ 8.3 qt (about 2.1 gal)
Engineering Assumptions
- Solids and recommended film thickness come from the product’s data sheet.
- Transfer efficiency depends on the gun, pressure and technique; the calculator notes about 65% for HVLP and 30–40% for conventional guns.
- Metallic and tri-coat colors may need extra coats.
Frequently Asked Questions
How much paint does it take to paint a car?
For a mid-size car the calculator suggests roughly a gallon each of sprayable base and clear; confirm with your paint system.
How much clear coat do I need?
About the same sprayable volume as the base coat in this calculator.
Why is sprayable volume more than unmixed paint?
Reducer and hardener are added according to the mixing ratio.
What is transfer efficiency?
The percentage of sprayed paint that lands on the surface rather than becoming overspray.
How much paint for a color change?
More than a same-color respray, because jambs and hidden areas are painted too.