Check the spec
Lengths and check-digit rules for this postal symbology are listed above.
Free tools · Logistics
Generate USPS Intelligent Mail postage symbols.
USPS four-state Intelligent Mail barcode for letters and flats (IMb). IMpb package data is a GS1-128 profile. Enter 20, 25, 29 or 31 digits for USPS Intelligent Mail below — lengths and check digits validate instantly in your browser before the symbol renders.
Postal barcode generator
Pick a post, type the data.
Runs locally in your browser. Nothing is uploaded; validation errors name the exact rule.
Style (module size, bar height, readable text)
Rendering symbol…
Specification
| Standards | USPS postal specifications |
|---|---|
| Character set | Digits only — 20, 25, 29 or 31 digits. Routing + tracking data per USPS spec. |
| Lengths | 20, 25, 29 or 31 digits |
| Check digits | Check-digit rules enforced by the native engine; see input hint. |
| Quiet zone | Calm quiet zones on both sides; pure black on white for sorter readability. |
| Capacity | Digits only — 20, 25, 29 or 31 digits. Routing + tracking data per USPS spec. |
Usage
USPS Intelligent Mail routes United States mail through automated sorters: print it on envelopes and parcels where United States carriers expect it.
- USPS Intelligent Mail on envelopes for United States automated sorting
- USPS Intelligent Mail on parcels with the example 01234567094986545671 as a starting point
- USPS Intelligent Mail proofs exported as SVG for print-safe output
Shape
Pros
- USPS Intelligent Mail is accepted by United States sorting automation.
- Lengths and check digits validate instantly with the exact rule named.
- SVG export stays sharp for envelopes and parcel labels.
- The symbol is read back locally before preview unlocks where a reader exists.
Cons
- USPS Intelligent Mail is single-purpose — it carries postal data, not general text.
- Wrong lengths or missing check digits are rejected instead of printed.
- Low contrast or tight quiet zones fail high-speed sorters first.
- Screenshots prove encoding, not sorter-grade print quality.
Form requirements
- Enter 20, 25, 29 or 31 digits.
- Digits only — 20, 25, 29 or 31 digits. Routing + tracking data per USPS spec.
- Preview and downloads stay withheld until local verification passes where a reader exists.
Sources
- USPS Intelligent Mail specifications (USPS)
Related formats
Keep exploring.
How it works
Three steps, all on your device.
The same engine that prints parcel labels worldwide, running in your browser.
Type the data
The on-device engine enforces the rest and appends check digits where the standard says so.
Verify, then print
The symbol is rasterized and read back locally before preview and downloads unlock.
Questions
USPS Intelligent Mail Generator & Specs, answered.
If you manage servers by hand, see the engineering services behind this tools series.
What do I type for USPS Intelligent Mail?
Digits only — 20, 25, 29 or 31 digits. Routing + tracking data per USPS spec. Try the example 01234567094986545671 first.
Does USPS Intelligent Mail need a check digit?
Digits only — 20, 25, 29 or 31 digits. Routing + tracking data per USPS spec. The engine computes or verifies it and names the expected digit on mismatch.
Is my data uploaded anywhere?
No. Encoding and verification run entirely in your browser — the page makes no network requests with your data, stores nothing, and wipes the field after ten idle minutes.
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