If you’re designing your own photo Christmas card, keep in mind that the image resolution should be 300dpi and no greater than 30mb - and text should be at least 8px. If you choose a folding Christmas card, traditionally the dimensions are 5.5” x 4.25”. And for flat Christmas greetings cards, it’s usually 5” x 7”. Lastly, Christmas postcards are 6” x 4.25” on average.