Car Door Magnets for Contractors: Sizing, Care, Do's & Don'ts
Your truck or van is parked in driveways, job sites and supply-house lots all day. If it's plain white, it's working for nobody. Car door magnets are the simplest way for contractors and home-service pros to turn a work vehicle into a rolling business card, without a permanent wrap and without losing the option to use the same truck on weekends. The catch: a magnet that's the wrong size, hard to read or poorly cared for can look sloppy, slide off on the highway or even mark your paint. This guide covers sizing, design, care and the do's and don'ts so your magnets look professional and keep bringing in calls.
Why contractors use car door magnets
Magnets sit in a sweet spot between doing nothing and paying for a full vehicle wrap:
- Removable: take them off for personal use, when you sell the vehicle, or when you switch trucks.
- Swappable: run a different set for a seasonal service (pressure washing in spring, gutter cleaning in fall) or for a second business line.
- Fleet-friendly: new hire, new truck? Order another pair with the same artwork instead of re-wrapping.
- Double duty on site: they also stick to steel surfaces like dumpsters, job trailers or metal gates as a temporary "work by" sign.
They're not a replacement for a wrap if you want full-coverage branding, but for a sole proprietor or a small crew they're often the fastest way to get visible.
Step 1: Measure the flat area of your door
Sizing is where most magnet mistakes start. A magnet only grips well on a flat, smooth steel surface. It will not stick to aluminum, fiberglass or plastic panels, and it won't hold properly over body lines, ridges, door handles or trim.
- Check that the door is steel. Hold a fridge magnet against it in a few spots. If it doesn't grab everywhere, find another panel.
- Find the largest flat rectangle. Use a tape measure to mark the flat zone between the window trim, the body line, the handle and the wheel well. Measure width and height.
- Leave a margin. Choose a magnet size that leaves a little clearance on every side of that flat zone, so no edge sits on a curve or a crease. Edges that lift are what catch wind at highway speed.
- Measure both doors. Driver and passenger doors aren't always identical on every vehicle, especially with a fuel door on one side.
Once you have your numbers, pick the closest size that fits inside them in the Car Door Magnets configurator. When in doubt, go slightly smaller: a magnet that fits fully on flat metal beats a bigger one hanging over a body line.
Step 2: Design for a moving target
People see your truck in traffic, at a red light or from across a parking lot. Treat the magnet like a mini billboard, not a brochure.
What to include
- Business name or logo, large and at the top.
- What you do in two to four words: "Roofing & Repairs," "AC Service & Install," "Licensed Electrician."
- One phone number, as big as the layout allows. This is the line that gets you calls.
- Website or short domain, smaller than the phone number.
- License number if your trade or local rules call for it on vehicles. Check your state and county requirements before you print.
What to leave off
- Long service lists. Pick your top service; the rest goes on your website.
- Multiple phone numbers, social handles and email addresses competing for space.
- Thin script fonts, light gray text or busy photo backgrounds.
Readability rules
- High contrast: dark text on a light background or white text on a dark one. Avoid color pairs that blend, like red on black.
- Bold, simple fonts: sans-serif typefaces read best at a distance.
- Breathing room: keep important text away from the edges and leave space between lines.
- Consistent branding: use the same colors and logo as your yard signs, business cards and door hangers so people recognize you everywhere.
The same "read it in a few seconds" logic applies to job-site signage. If you also put up 4mm Coroplast Signs in front of projects, matching your magnet design ties the two together.
Step 3: Prepare your file correctly
- Set the document to the exact magnet size you ordered, plus any bleed the product page asks for.
- Use a vector logo (AI, EPS, SVG or a vector PDF) so edges stay sharp when enlarged.
- Keep phone numbers and key text inside the safe zone, away from the trim line.
- Design in CMYK so colors are predictable in print.
- Proofread the phone number twice. A typo here makes the whole sign useless.
Step 4: Install and care for your magnets
Most paint problems come from dirt and moisture trapped under a magnet that never moves. A little routine prevents that.
Installing
- Wash and fully dry the door and the back of the magnet before applying.
- Apply in a cool, shaded spot. Hold the magnet by two edges, let the center touch first, then smooth outward so no air pockets remain.
- If your vehicle was recently painted or repaired, ask your body shop when the paint is fully cured before putting a magnet on it.
Maintaining
- Remove and clean regularly. Sign makers such as VE Signs recommend removing the magnet at least weekly to clean, and more often in harsh conditions.
- Clean both the door and the magnet back with mild soap and water, then dry completely.
- Take magnets off before automatic car washes.
- Peel from a corner. Don't pull from the middle or fold the magnet.
Storing
- Store flat, or roll loosely with the printed side facing out. Never crease it.
- Don't leave magnets on a hot dashboard or stacked under heavy tools.
Car door magnet do's and don'ts
| Do | Don't |
|---|---|
| Measure the flat steel area first | Place a magnet over body lines, handles or trim |
| Use one big phone number | Squeeze in every service and social handle |
| Use high-contrast, bold fonts | Use script fonts or busy photo backgrounds |
| Remove and clean at least weekly | Leave it on for months without checking |
| Store flat or loosely rolled, print side out | Fold, crease or toss it in the truck bed |
| Match your other signs and cards | Use a different logo or color scheme on each item |
Quick checklist before you order
- Door confirmed steel with a test magnet
- Flat area measured on both doors
- Size chosen with clearance on all sides
- Name, service, one phone number, website (and license number if required)
- High contrast, bold fonts, nothing near the edges
- Vector logo, CMYK file, phone number proofread twice
Extend the message beyond the truck
Your vehicle gets attention; the follow-up keeps it. Many contractors hand out Magnet Business Cards so homeowners can stick their number on the fridge for the next repair, and leave Tearoff Door Hangers in the neighborhood around an active job with a tear-off offer. Use the same logo, colors and phone number across all of them.
FAQs
Will a car door magnet damage my paint?
Problems usually come from grit and moisture trapped underneath over time. Applying the magnet to a clean, dry, fully cured surface and removing it regularly to clean both sides is the best way to protect your paint.
Can I put a magnet on any vehicle?
Only on flat, smooth steel. Many newer vehicles use aluminum or composite panels in places, so test each door with a small magnet before you order.
Can I drive on the highway with car door magnets?
A properly sized magnet that sits fully on flat metal, with no lifted edges, is designed for everyday driving. Check it before each trip, and if you notice an edge lifting, remove it, clean it and reapply, or choose a smaller size that fits the flat area better.
Get your car door magnets right the first time with KEOPSY
At KEOPSY, a real person reviews every file before it prints, so issues like text too close to the edge or a low-resolution logo get flagged before your magnets are produced. Car Door Magnets start at $8.39 as listed on keopsy.com, and you can choose your size and options in the live configurator. Don't have a design yet? Try the AI Design Studio to create a clean, readable layout in minutes, then match it on your cards, signs and door hangers.