Check Your Artwork Size and Resolution
Enter your magnet's finished size and your image's pixel dimensions, and it works out whether the print will come out sharp. It runs in your browser, so the image itself never leaves your computer.
The calculation behind the check
Working out the dots per inch
The check divides the pixel width of your image by the finished width of the magnet, after converting the magnet's size from millimetres into inches (one inch is 25.4 mm). A 600-pixel-wide image set against a 60 mm magnet works out at roughly 254 pixels per inch, and the same sum is done separately for the height. Whichever of the two numbers comes out lower is the one that decides whether the image will print sharp or soft, because a print can only be as good as its weakest dimension.
What 300 dpi actually buys you
300 dots per inch is the point at which a printed image on magnetic sheet reads as continuous to the eye at the distance a fridge magnet is normally seen from, which is close. Below that figure the dots making up a photograph start to separate, and faces, small text and fine logos soften first. An image at 150 dpi is not broken, it is simply printed at half the sharpness, and on a small magnet that loss is more visible than the same shortfall would be on a poster seen from across a room.
The figure the check returns describes the file you have entered, nothing more. A printer's own software, colour profile and lamination film all have a bearing on how the finished magnet actually looks, so the result is a resolution check on your artwork.
Why bleed costs more at small sizes
Bleed is the printed area that runs beyond the finished edge, so that the trimming blade can move a millimetre either way without leaving a pale sliver at the border. On a large print that margin is a thin strip of the whole design. On a magnet the size of a credit card, 2 to 3 mm of bleed on each edge is a meaningful share of the face, which is why the safe area, the inset zone where no text or logo should sit, has to be set from the actual finished size. Confirm the exact bleed your printer works to before you set up the file, since it varies slightly between suppliers.
The full specification checklist, including bleed and safe area figures to put in front of a printer, is covered in Ordering Printed Promotional Magnets: What to Specify. The method behind this check, including its limits, is set out in Understanding Artwork Size and Resolution Checker.
What to do when the resolution falls short
Making an image larger in your design software does not add detail. It spreads the same pixels over more millimetres, so the file dimensions change but the sharpness does not. If the checker returns a result below 300 dpi, resizing the image upward will not move that number into range, whatever the software reports as the new size.
Cropping removes pixels, it does not add them
Cropping a photograph cuts away part of the pixel grid, so it can only lower the effective resolution of what is left. Cropping is worth doing when the original has pixels to spare, a wide shot you only need the centre of, but it cannot rescue an image that was already close to the limit at full size.
When the source image itself needs replacing
If an image still falls short once it has been sized correctly and without cropping, the fix is a different original. That usually means one of:
- a rescan at a higher setting, if the artwork started life on paper
- a photograph taken at the camera's full resolution
- a different source image altogether, where the one you have was never captured at a size that would cover the finished magnet
None of that is a flaw in the checker. It works from the pixel dimensions and finished size you give it, so once those are accurate the result stands or falls on what the image can actually deliver. For how image quality holds up at small print sizes more broadly, the guide on custom and photo magnets covers cropping and finish choices in more detail.
Questions about preparing artwork
Do I need to upload my artwork file to use the checker?
No file goes anywhere. You type in the magnet's finished size in millimetres and the pixel dimensions of your image, and the check runs in your browser. Nothing is sent to a server, so you can check a confidential design without it leaving your machine.
What file format should my artwork be in?
The checker works from the pixel dimensions of your image rather than the file itself, so it makes no difference whether you're working in a JPEG, a TIFF or a layered PDF. Printers commonly ask for a high-resolution PDF or TIFF. Confirm your printer's preferred format before you send the final file.
Should my artwork be in CMYK or RGB?
Print separates colour into cyan, magenta, yellow and black (CMYK), while a screen builds colour from red, green and blue (RGB). Colours can shift when a file moves between the two, particularly in blues and greens. The checker only tests resolution, not colour mode. Confirm with your printer whether they want a CMYK file supplied, or whether they convert an RGB file on press.
What is bleed, and how much should I add?
Bleed is the printed area that extends beyond the finished edge of the magnet. It means that small variation in trimming doesn't leave a white border at the edge of the piece. For most magnet printers, 2 to 3 mm on each side is standard, but the exact figure varies by printer and by die shape, so confirm it before you finalise your file. The checker shows the bleed dimensions for the size you enter.
What does a printer mean by 'safe area'?
Safe area is the inset zone within which no text, logo or important detail should sit. Anything placed closer to the edge risks being trimmed off, or sitting uncomfortably close to the cut line even if it survives. The checker returns the safe-area dimensions alongside the bleed for the size you enter, so you can set your canvas up correctly before you start designing.
Artwork Size and Resolution Checker
Enter your fridge magnet's finished size and the pixel dimensions of the image you intend to print. Nothing is uploaded, everything is calculated here in your browser as you type.
Effective print resolution
Document size to set up (including bleed)
Safe area (keep text, logos and phone numbers inside this)
Pixels needed for 300 dpi across the full bleed
What this check can and cannot tell you. These figures are worked out from the numbers you typed in. The tool never sees your image file, so it cannot tell whether a picture has been enlarged from a smaller original, saved with heavy compression, or simply photographed out of focus — any of which can print badly at a dpi figure that looks perfectly healthy here.
It compares resolution against finished size, and nothing else: not colour mode, not file format, not how the artwork sits on the page. And 300 dpi is the figure commercial print generally works to rather than a universal requirement. Treat the result as a guide to the artwork you already have, not a promise about the finished print, and confirm bleed, safe margin and file specification with whoever is doing the printing.
How this is worked out
Dots per inch, dpi, is simply the pixel count divided by the physical size in inches, and 25.4 millimetres make one inch. This tool divides your image's pixels by the finished size converted to inches on each axis, and reports whichever axis comes out lower, because that weaker axis is the one that will actually be visible when the magnet is printed and trimmed.
300 dpi is the figure commercial print generally works to because at normal viewing distance it renders fine detail, small type and clean line edges without visible pixellation. Below that figure, detail starts to soften; well below it, the image is likely to look blurred or blocky rather than sharp.
Bleed exists because the trim at the cutting stage moves very slightly on every run. If the artwork stops exactly at the finished edge, that tiny movement can expose a thin white sliver of uncut stock. Extending the artwork past the trim line on every side means the cut still lands inside solid colour or image whichever way it drifts.
A safe area exists for the same reason, seen from the inside: anything important, such as text, a logo or a phone number, is kept a margin's distance back from the trim edge, so that if the cut drifts slightly inward it does not slice through wording or crop a logo awkwardly.
These figures are a check on the artwork you already have, worked out from what you have typed in. They are not a promise about what any particular printer requires: confirm bleed, safe margin and file specification with whoever is doing the printing before you send artwork.