Is 16pt cardstock too thick for mailing postcards?

16pt cardstock measures about 0.016", which sits right at the USPS maximum thickness for the postcard postage rate. In practice most post offices accept it without any issue.

• 16pt is at the upper edge of the 0.016" postcard limit, not over it.
• For occasional or premium sends, 16pt mails fine and feels substantial.
• For very high-volume campaigns, 14pt stays comfortably under the limit and avoids any processing hiccups.

If you are mailing in large quantities and want zero surprises at the counter, 14pt is the safer default.