Where the extra area hides
The outside face of a panel is the part you can see and the part everyone counts. What gets missed is everything that curls away from you: the return around a door frame, the lower edge that folds under the sill, the flange along a hood where it meets the fender, the underside of a decklid, the jamb behind the door. None of those are large individually. Added up on a four panel job they are routinely a sixth of the total, which is exactly the margin most people were relying on.
Bumper covers are the worst offender because they are not flat and their outline lies about their size. A cover that measures five feet by two feet in silhouette wraps under at the bottom, wraps around at the ends, and carries a lower valance. The surface you actually have to cover is well beyond the ten square feet the tape measure suggested.
Both sides is a different word from twice
| Scope | What the allowance is doing | Rough figure |
|---|---|---|
| Outside faces only | A blow-over or a single panel blend, nothing opened | 0% |
| Outside plus edges and jambs | Panels flipped out, jambs cut in, edges done | 10-20% |
| Fully inside and out | Doors, hood and lid sprayed on both faces | 60-80% |
Painting a door inside and out is not double the area, because the inner face is broken up by the window aperture, the hardware and the parts that stay masked. It is also not the same amount of work per square foot: inner faces are awkward to reach with a gun, they take longer to spray, and they flash at a different rate to the flat outer skin because the air does not move through them the same way.
Why the size classes are so coarse
Panel area does not scale neatly with vehicle length. A pickup has a small hood relative to its footprint and enormous bed sides. A crossover has a tall door with more area than a sedan door of the same length. The class factors here shift every panel by the same amount, which is a simplification that is good enough for ordering material and not good enough for anything else. If you have measured one panel and found the figure ten percent off, put ten percent into the adjustment field and the rest of the list moves with it, which is usually closer than arguing about the class.
For a full respray, the figure this page gives for every exterior panel on a midsize car lands in the region of two hundred square feet with a normal jamb allowance. That is the same order as the hundred to a hundred and thirty square feet often quoted for outside faces alone, and the gap between those two numbers is the jambs and edges that the smaller figure was never counting.
What the area does and does not decide
Area sets material. It does not set time, and the two come apart badly on small jobs. A four inch chip in the middle of a door is a fraction of a square foot of paint and most of a day of work, because the preparation, the masking, the colour match and the blend into the surrounding panels are all the same regardless of how small the damage was. Anybody who has quoted a repair by the square inch has learned this once.
Structural work is the other place the number stops meaning anything. If a panel is a bolted cover you are painting, this page is arithmetic about surface. If it is welded structure, if the vehicle has been in a collision hard enough to move anything behind the skin, or if airbags, seatbelt pretensioners or driver assistance sensors are involved anywhere near the repair, that is collision work with measurement, procedures and calibration requirements that belong to a qualified shop. Nothing on this page speaks to whether a repair is sound.
Questions people ask
How accurate are these panel figures?
Treat them as within about fifteen percent for the class they describe, which is enough to order material with a sensible margin and not enough to quote from. Panel sizes vary between models of the same class and between years of the same model, and a panel that has been replaced with a different part number can be a different shape entirely. The one number worth measuring for real is any panel you will be pricing repeatedly, because once you have taped it out you can put the difference into the size adjustment and every other panel moves with it.
Does this include the roof of a pickup or SUV?
Yes, when you enter a roof. The roof figure is scaled by the class factor along with everything else, so a full-size pickup roof comes out larger than a midsize car roof. Bed sides are separate because a pickup has them and nothing else does, and they are large: two bed sides on a full-size truck are comparable to all four doors on a sedan. Bed floors, tailgate inner faces and bed liners are not in the list at all.
Why is my total higher than the square footage I see quoted for a whole car?
Because most quoted figures are outside faces only. A hundred to a hundred and thirty square feet for a car is the paint you can see standing next to it. Add the jambs, the edges, the underside of the hood and the returns, and the surface a gun has to cover is substantially more. The comparison line on this page uses the same allowance for both sides of the comparison so that the ratio stays honest.
Can I use this for a motorcycle, a trailer or a boat?
Not from the panel list, which is shaped around a car. Measure the surfaces and put the total into the measured extras field, and the allowance and the reporting still work. A motorcycle tank, side covers and fenders together are typically under fifteen square feet, which sounds trivial until you find that the material minimum you can buy and mix accurately is the real constraint rather than the area.
Should the area include what I mask off?
No. Enter only what will be sprayed. Masking affects your time, not your material, and it affects it a lot: a job with glass, trim, lamps and badges to mask can spend more hours in preparation than in the booth. If you are building a time estimate rather than a material estimate, the panel count matters more than the square footage, and the refinish labor hours calculator on this site works from panels rather than area for exactly that reason.