File requirements to upload your own design Estimated reading: 1 minute 636 views To upload your own design there are some size requirements for your file. Here they are. Mailfold has 1 letter and 3 different postcard sizes: 4′ × 6′ PostcardThe design must be 1875px × 1275px. That’s 4.25″ × 6.25″ @ 300dpi with the bleed. 6′ × 9′ PostcardThe design must be 2775px × 1875px. That’s 6.25″ × 9.25″ @ 300dpi with the bleed.6′ × 11′ PostcardThe design must be 3375px × 1875px.That’s 6.25″ × 11.25″ @ 300dpi with the bleed.8.5′ × 11′ LetterThe design must be 3375px × 2625px.That’s 8.5.25″ × 11.25″ @ 300dpi with the bleed.The files format must be PNG, PDF, or JPG. Remember our postcards have an area on the back reserved for the sender and contact address. You can always visualize the files format after you click on ‘Upload Design Files’.