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Free USPS IMpb barcode generator.
The Intelligent Mail package barcode (IMpb) carries the USPS tracking number on parcel labels. Enter its 22 or 26 digits and download it.
How to create a USPS IMpb barcode
-
01
Build the tracking number
Type 92 for a nine-digit Mailer ID (MID) or 93 for a six-digit one, then the Service Type Code, MID and serial number. With 21 or 25 digits, the generator adds the check digit.
-
02
Add the routing ZIP Code
For routing, type
420, the ZIP Code and\Ffirst, with Escape sequences on. -
03
Size it for your label printer
Set Module width to Pixel and Resolution (dpi) to your printer's. At 300 dpi, 5 pixels give 0.42 mm (16.7 mil), inside USPS's preferred range.
What is the USPS IMpb?
The Intelligent Mail package barcode (IMpb) is the GS1-128 barcode USPS requires on all commercial packages. It carries the tracking number your customers look up on USPS Tracking, optionally with the destination ZIP Code.
Who prints the IMpb
Commercial mailers print channel AI 92 or 93 with their own MID. PC Postage and meter systems use 94 and the vendor's two-digit source identifier from USPS. With USPS Returns, merchants print an IMpb and their MID on each prepaid return label.
Shippers also send USPS each tracking number in an electronic file, such as the Shipping Services File. Serials must stay unique for 120 days, so PC Postage customers with 100,000 pieces or more in six months need a six-digit MID.
One scan for routing and tracking
A concatenated IMpb joins the routing ZIP Code and the tracking number in one symbol, and no other barcode on the parcel may carry the routing code. USPS charges a Package Quality Noncompliance Fee when a mailer's barcodes miss its thresholds.
At least 70% of a mailing must grade B or better, the rest at least C, measured with a 10-mil aperture. The drawing shows the example at 0.42 mm modules with the minimum bar height and 0.25-inch clear zones.
Single labels online, shipping volumes in TEC-IT software
PNG, GIF and JPG downloads of the IMpb are free; SVG and higher print resolution come with a plan. One label's barcode needs no account; for a day's shipments, import the tracking numbers into a data sheet after a free sign-in.
TEC-IT's Barcode Reference documents the IMpb with its own mod 10 check digit method for TBarCode SDK and TFORMer. A shipping application built on the SDK, or TFORMer Server fed by the order system, prints it on every label.
USPS IMpb at a glance
- Type
- GS1-128, code set C only
- Specification
- USPS Publication 199; USPS2000508
- Length
- 22 or 26; 30 or 34 with 420 and ZIP Code
- Check digit
- Mod 10 on the tracking number only
- X-dimension
- 0.33–0.53 mm (13–21 mil); 15–17 mil preferred
- Bar height
- At least 19.05 mm (0.75 in)
- Clear zones
- 10X left and right; 3.18 mm (0.125 in) above and below
How the IMpb tracking number is built
| Field | Digits | Example |
|---|---|---|
| Channel AI | 92 (nine-digit MID), 93 (six-digit MID), 94 (PC Postage) | 92 |
| Service Type Code | 3, from USPS's list | 123 |
| Source identifier | 2, only with 94 | — |
| Mailer ID | 9 starting with 9, or 6 starting with 0–8 | 912345678 |
| Serial number | 7 or 11 (nine-digit MID), 10 or 14 (six-digit); 2 fewer with 94 | 1234567 |
| Check digit | 1, mod 10 like a GTIN's | 0 |
GS1 reserves 91–99 for company-internal data; USPS gives 92–94 its own meaning. Numbers starting with 91 follow the legacy construct.
IMpb width, placement and the IMmb
- Width: 167 modules, or 244 with 420 and a 9-digit ZIP Code. At 0.423 mm the 244 measure 103.3 mm, more than a 4-inch label; at 203 dpi, 3-dot modules give 91.6 mm.
- Placement: on the largest side, never over an edge; it should sit next to the delivery address.
- IMmb: since 19 January 2025, domestic labels must also carry the same data as a 20 × 20 GS1 DataMatrix left of the delivery address.
IMpb mistakes and how to fix them
- Keeping the generator's text line. At step 3's size it sits 0.85 mm below the bars, in regular Arial; USPS wants bold type 3.18–6.35 mm below. Switch off Show human-readable text and set the number in your layout.
- Printing the default image. Its one-pixel modules at 96 dpi measure 0.26 mm (10.4 mil), under the 13-mil minimum. Size it as in step 3.
- 420 and ZIP Code without \F. The generator refuses the digits run together; type
42020260\Ffirst.
IMpb compared with related barcodes
Frequently asked questions
Learn more about USPS IMpb.
Can I create an Intelligent Mail barcode (IMb) here?
Where do I get a Mailer ID for the IMpb?
Why does the text under my IMpb not show the ZIP Code?
Can an IMpb be shorter than 0.75 inch?
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