What is the Intelligent Mail barcode?
The Intelligent Mail barcode (IMb) is the 65-bar, 4-state barcode the United States Postal Service uses to sort and track letters and flats. Each bar is one of four shapes: full height, ascending, descending or a short tracker. Mailers need it for automation prices, and it replaced the older POSTNET barcode in 2013.
| Bars | 65, each in one of 4 states |
|---|---|
| Data | 20-digit tracking code + 0, 5, 9 or 11-digit routing code |
| Length | About 3 inches; USPS-B-3200 sets the exact tolerances |
| Read by | USPS mail processing equipment (not phone cameras) |
What goes in the 31 digits
| Field | Digits | What it is |
|---|---|---|
| Barcode ID | 2 | Usually 00; the second digit must be 0–4 |
| Service Type ID | 3 | The mail class and services, like First-Class with tracing |
| Mailer ID | 6 or 9 | Assigned to you by USPS; 9 digits if it starts with 9 |
| Serial number | 9 or 6 | Your number for this mailpiece; fills the tracking code to 20 digits |
| Routing code | 0, 5, 9 or 11 | The delivery ZIP, ZIP+4, or ZIP+4 plus delivery point |
You get a Mailer ID from the USPS Business Customer Gateway. For Full-Service mailings, serial numbers must stay unique for 45 days.
How to make one
- Type the 20-digit tracking code, then the routing ZIP. Spaces and dashes are ignored. The tool checks the length and splits the number into its fields so you can check it.
- Download SVG or PDF and place it on the mailpiece without stretching. The size is fixed by USPS, so there's no bar width to choose.
- Follow the USPS placement rules for your mail class, and print with good contrast on a light background.
Phone cameras and the barcode checker can't read the 4-state Intelligent Mail barcode; it's designed for USPS sorting machines. USPS offers its own tools for testing IMb quality.
