Determining rates for First-Class Single Piece mail using MailStream Plus

Products affected:  MailStream Plus™, All Platforms
The postage rates mentioned below were current as-of April  2019, at this link:
Current rates can always be found at on the "Price List (Notice 123)"

A MailStream Plus™ (MSP) user asked how single piece rates were determined for a First-Class letter mailing, referring to lines B4, B5, and B6 on a 3600-FCM Postage Statement.
On the 3600-FCM form, lines B4, B5, and B6 are defined like this-

B4 Residual                                              X             =
   From First-Class Mail Mailing
   (Includes Up to 1 oz. and Between 1 oz. and 3.5 oz.)
B5 Nonpresorted/                                     X             =           
B6 Single-Piece                                        X             =
    From USPS Marketing Mail Mailing
  • If the mailing is all 1 oz pieces, then the single piece rate mail will be on line B4.
  • If the mailing is mixed 1 and 2 oz pieces, then a 'blended' rate applies, and single pieces go on line B5.
  • If the mailing is all over-1oz-up-to-2-oz, then the pieces go on line B6.

If you look in the rate chart referenced at the top of this page, in the section-
First-Class Mail
the second chart is for Single Piece letter mail rates and gives the postage for
B4 (1oz) 0.56 
B5 (blended) 0.50 
B6 (>1oz up to 2oz) 0.55
  • One other option that can be advantageous, depending on make-up of a mixed 1 and 2 oz mailing, is that the USPS (and MSP) allows you to prepare single piece rate mail in separate trays by weight (ounces).  
  • And then each piece will not be charged the blended rate, but will be charged either the 1 oz or 2 oz rate depending on it's weight.
  • ALG PS position 20=S turns on this option.
UPDATED:  April 19, 2019