All commercial postage categories have minimum quantities of mail that must be met. Beyond that, your level of sort and the number of pieces in each sortation may qualify your mail for even lower prices.
For single-piece (full price) First-Class Mail: no minimum.
For Presorted and automation First-Class Mail: 500 pieces.
For Standard Mail: 200 pieces OR 50 pounds.
For single-piece (full price) Parcel Post, Library Mail, and Media Mail: no minimum.
For destination entry Parcel Select: 50 piece minimum per mailing.
For Presorted Bound Printed Matter: no minimum.
For Presorted and Carrier Route Bound Printed Matter: 300 pieces.
For Commercial Library Mail: 300 pieces.
For Commercial Media Mail: 300 pieces.
Within each class of mail, there also are minimum quantities to qualify for a particular price, depending on how finely your mail is sorted. For example, if 1,000 pieces were all addressed for delivery to one ZIP Code, they would get a better price than 1,000 addressed for delivery nationwide.
How size and shape affect prices
How weight affects prices
How distance affects prices
Destination entry discounts
Calculate postage for any class of mail or price discount
List of all prices and fees:
Download Adobe Acrobat Reader