Postage Rates 2024 By Weight Calculator. Explore the usps postage rate shifts for postcards, flats, and letter sizes in 2024, and optimize your mailing strategies. For large envelopes (flats) up to 15.994 oz., postage prices vary based on weight and destination, starting from $3.15.
Changes by usps for postcards, flats & letter size. Ship products faster & more reliably with shiprocket