Custom and photo magnets: getting one you will still like in a year

A fridge magnet is printed small, usually somewhere between 50 × 50 mm and 90 × 60 mm, and that changes what counts as good enough for a photograph. A resolution that looks sharp on a phone screen can print soft, blocky or pixelated once it is reduced to the size of a magnet, because the file simply does not hold enough detail for the print area.

Working out the pixel dimensions you need

Print resolution is measured in dots per inch (dpi), the number of printed dots packed into each inch of the finished piece. For photographic printing, 300 dpi is the standard most magnet printers work to, and it is worth calculating in pixels.

Take a common promotional size, 70 × 45 mm. At 300 dpi that works out to roughly 827 × 531 pixels. A photo taken on a modern phone camera comfortably exceeds this, but a photo saved from a website, a screenshot, or an image that has already been cropped and resized once will often fall short. The artwork size and resolution checker takes the finished size and the pixel dimensions you read off your own file and returns the dpi on the weaker axis, since that is the one that will actually be visible on the print. Nothing is uploaded; the numbers are typed in and the result updates as you go.

Why tight crops fail first

A close crop, such as a single face filling most of a 70 × 45 mm magnet, is the version most likely to show a resolution problem, because there is nowhere for a soft or blocky area to hide. A wider shot with some background spreads the same pixel count over more visual detail, so the same file that looks fine as a landscape photo can look noticeably rougher once cropped tightly to a face or a small object.

Cropping also interacts with bleed, the printed area that extends slightly beyond the finished edge so that small variation in trimming does not leave a white line at the border. If your printer asks for 2 to 3 mm of bleed on each side, a tight crop needs to hold up right to that outer edge. Confirm the bleed allowance and the safe area, the inset zone where nothing important should sit, with your printer before you finalise a crop; the checker will work out the document size and safe area for a given bleed and margin, and let you adjust both if your printer specifies different figures.

What to check before you upload

• The pixel dimensions of the file match or exceed 300 dpi at the finished magnet size, calculated across the bleed size.
• The crop you intend to use has been applied to the full-resolution original.
• Faces, text or any detail you want sharp sit inside the safe area, clear of the bleed edge where trimming variation occurs.
• The file has not been saved and re-saved multiple times as a compressed format, since repeated compression softens detail even when the pixel dimensions stay the same.

The checker can only assess the numbers in the file, and a figure it returns is a check on the arithmetic rather than a guarantee that any particular printer will accept the result, so it is still worth reviewing the cropped image yourself at full size on a screen before you order.

The finish over a printed photo magnet, meaning the layer bonded on top of the ink, decides more about how it looks in a year than the photo itself. Two magnets printed from the same file can age completely differently depending on whether that top layer is a laminate film, a bare printed surface, or a resin dome, and each of those constructions fails in a different way.

Laminated prints

A gloss or matte lamination is a thin plastic film bonded over the printed face after printing, sealing the ink against scuffing, grease and moisture. A properly laminated photo magnet generally keeps its colour and surface finish for years on an indoor fridge door, though direct sunlight through a kitchen window will still fade it over time, laminate or not. Matte lamination hides fingerprints and light scratches.

Unlaminated print

A magnet printed directly onto the magnetic sheet or a paper face with no film over the top has nothing standing between the ink and the room it sits in. Colour loss shows first in reds and yellows, and a face that starts to look washed out or a background that shifts towards grey is usually this construction. Ask your printer whether lamination is included as standard on a photo magnet or sold as an extra, because it is not always obvious from a price list.

Epoxy dome finishes

An epoxy dome, a clear resin dome applied over a printed insert, is common on souvenir and small photo magnets and seals the image under a hard, glass-like surface. Cheaper resin formulations can yellow under sustained light over a few years, turning a white background faintly amber even though the print underneath has not changed at all. A yellowed dome cannot be cleaned back to its original colour, since the discolouration is in the resin itself, not on the surface.

Where fading and peeling actually start

• A magnet fixed near a window with direct sun for part of the day, which fades laminate, unlaminated print and resin domes alike, just at different rates.
• A position close to an oven or hob, where repeated heat can soften some laminate adhesives over time.
• An edge that was not fully sealed during lamination, letting moisture creep under the film and start a peel that spreads inward from one corner.
• Frequent handling at the same edge or corner, which wears a laminate faster than the flat face of the magnet ever will.

None of this is something you can judge from a product photo or a price list. Confirm the lamination type, and whether an epoxy dome uses a UV-stable resin, directly with your printer before you order a photo magnet you expect to keep on display for more than a season.

A save-the-date magnet is usually produced in a batch of fifty, a hundred or more, all identical, and every guest sees the same crop and the same colour at once. That makes proofing more important than it is for a single custom photo magnet, because a mistake is not caught on one piece and quietly reprinted. It is caught after the whole run has gone out in envelopes.

Proofing before the full run

Ask your printer for a proof, either a digital PDF or a physical sample, before they run the full quantity. A digital proof shows colour and crop but not how the lamination will look under light, so where the run is large enough to justify it, a physical sample is worth the extra step. Check names, dates and venue details on the proof letter by letter, since a spelling error that reaches a hundred printed magnets is a hundred magnets to redo.

Resolution problems show up here too. A save-the-date is usually printed small, often close to the 70 × 45 mm range used for other promotional magnets, and a photo that looked sharp on a screen can print soft once it is reduced to that size. Before you send final artwork, use the artwork size and resolution checker to see whether your image's pixel dimensions hold up at the finished size you're printing, and to check the bleed and safe area against what your printer has specified.

Posting magnetised items

A magnet posted inside a card counts as a magnetised item for postal purposes, and Royal Mail's guidance on restricted and prohibited items covers goods that produce a magnetic field, because a strong enough field can interfere with sorting equipment and, for international post, with aircraft instruments. This mostly concerns industrial or neodymium magnets, but the position can change and varies for international versus domestic post. Check Royal Mail's current guidance before you post a batch, particularly if any guests are overseas.

What to check with your printer

• Whether they supply a digital proof, a physical sample, or both, and at what quantity a physical sample becomes worth requesting.
• The finished thickness of the magnetic sheet, since a thinner sheet posts more easily but a very thin one can arrive bent inside an envelope.
• Whether the magnet needs a card sleeve or envelope insert to keep the corners from catching in a letterbox.
• Their current position is on posting magnetised items in bulk.