The slot on most paper trimmers is 1/4” wide. This just happens to be the maximum thickness allowed for cards and letters. When your card is ready to post simply slip it into the envelope, and slide it through the slot on your paper trimmer. If it fits… it ships! Otherwise add that extra postage or hand deliver.
To check the weight, use a digital kitchen scale. Be sure you have a scale that you can easily read once the mail is placed on it.
Tips courtesy of artymaz