Image specs for A5 & A6 postcards (and social sharing)

Warning: 70% of designers miss some specs

This page has some specific requirements which will be checked. If they aren't followed it may cause the printed postcard images be different than designed. So double check for each type:

1. Web images: RGB colours, smaller size, web image format
2. Print images: CMYK colours, 300 dpi, larger size, jpg format only + 3mm 'bleed' around the image (areas of the image that will be cut off)
3. Social sharing image: open graph dimensions (not postcard dimensions), web optimised

A5/A6 Print image specifications

The print version of the image(s) will appear on the image side of the printed postcard. It can be slightly different from the web version.

The message side of the postcard is standard and custom designs are not yet possible. They needs to be high quality (2-8 MB) so the print quality is good. Technically this means:

1. Size: 2800 pixels wide x 2000 pixels high (min 2480 px x 1748 px if at 300 dpi) which equals 210mm wide x 148mm. Flip that for tall postcards. JPEGs should be saved in high quality mode (90%+ or Photoshop level 12)
2. Crop & bleed area: Images are cropped/cut 5mm (60 pixels at 300 dpi) on each side so the postcard is borderless/edge-to-edge. Size (1 above) includes this crop area. The cut is often off by 1 mm in any direction. So the 5mm crop/bleed gives allowance for variation. Make sure there is no critical content in this 5mm edge: it will be cut off. If you want a border on the final result, make it extend past the 5mm crop edges.
3. Margin: A further 5mm (60 pixels at 300 dpi) margin 'unsafe' area (on top of the crop area) with no crucial design elements as the cutting may drift into this space.
4. No white border/crop marks unless you want this printed.
5. Resolution: 300 dpi - lower DPI value may mean a lower print quality and different pixel-to-mm conversion than above
6. Colour model: CMYK for print
7. File format: JPEG only (not PDF nor png/tiff/webp as these don't support CMYK colours)
8. Avoid: tiny white text on a colour background - it may not print clearly

Web image specifications

Web images are web-optimised versions of the postcard print images. They are used:

1. On the action web pages when people select which image they want their postcard to have
2. The first image is also used on landing page.
3. The sender's selected image is used on the success page
4. They are also be used when sharing on social media if no open graph image is supplied

They need to be web optimised quality (few hundred KB) so the page load time is fast. Technically this means:

1. Size: Multiple designs: 500 pixels wide x 352 pixels high (or a w:h ratio of 1.4187 like 1000 x 704 or 1200 x 845). One design only?: 1146 pixels wide x 800 pixels high (or a ratio of 1.4187).
2. Colour model: RGB colours
3. Resolution: 72 dpi and in any web friendly format (webp/png/jpg).

Social sharing specifications

To automatically include a properly sized image when sharing to Facebook, Twitter/X, WhatsApp, Slack and much more, provide an image with the following specifications (open-graph image spec):

1. 1200 x 630 pixels max
2. Under 300kb in size (max 500kb but test it)
3. It can be any web supported format: jpeg, png, webp, svg, etc.