A domestic USPS tracking number usually starts with 92, 93, 94 or 95 and is 22 digits long, while an international USPS number starts with two letters and ends in “US,” such as CP 000 000 000 US. Those first two digits tell you how the label was created, not which mail service was used; the service is coded in the three digits that follow.
That second point catches a lot of people out. Many guides claim “9400 means Ground Advantage” or “9205 means Priority Mail,” but USPS’s barcode specification, Publication 199, says the opening digits identify the label channel. This guide shows what each common starting pattern means and how to tell a USPS number from another carrier’s.
What Does a USPS Tracking Number Start With?
Almost every domestic USPS package label carries an Intelligent Mail package barcode (IMpb), and the tracking number printed under it begins with a two-digit channel application identifier. Publication 199 lists four values:
| Starts with | What it means | Where you’ll see it |
|---|---|---|
| 92 | Commercial mailer with a nine-digit Mailer ID | Labels printed by larger business shippers |
| 93 | Commercial mailer with a six-digit Mailer ID | Labels printed by high-volume business shippers |
| 94 | USPS APIs, PC Postage providers and postage meters | Labels bought online, including most online postage platforms |
| 95 | USPS Retail counters and self-service kiosks | Packages paid for at a Post Office |
So the same Priority Mail package can start with 95 if you paid at the counter and with 94 if you printed the label online. The tracking results page at USPS.com always names the actual mail class, which is the reliable way to confirm the service.
What Do the Digits After the First Two Mean?
After the channel identifier come a three-digit service type code, the Mailer ID, a serial number and a single check digit. Publication 199 describes those five parts as the full tracking number.
| Part | Length | What it tells you |
|---|---|---|
| Channel application identifier | 2 digits | How the label was created (92, 93, 94 or 95) |
| Service type code | 3 digits | The mail class plus any extra services, such as Signature Confirmation |
| Mailer ID | 6 or 9 digits | The business or postage system that printed the label |
| Serial number | Varies with Mailer ID length | The individual package; it must stay unique for 120 days |
| Check digit | 1 digit | A MOD 10 digit that catches typing errors |
Because the service type code sits in digits three to five, the first four digits combine the channel and the start of the service code. That’s why patterns like “9400” or “9205” appear so often, and why they shouldn’t be read as fixed service labels. Our guide to USPS tracking code formats breaks the anatomy down further.
Which USPS Tracking Number Patterns Are Most Common?
USPS publishes sample formats for its trackable services. The table below shows those samples with zeros for the unique digits. Treat the opening digits as typical examples, since the label channel can change them.
| Service | Sample format | Length |
|---|---|---|
| USPS Tracking (most packages) | 9400 1000 0000 0000 0000 00 | 22 digits |
| Priority Mail | 9205 5000 0000 0000 0000 00 | 22 digits |
| Certified Mail | 9407 3000 0000 0000 0000 00 | 22 digits |
| Collect on Delivery | 9303 3000 0000 0000 0000 00 | 22 digits |
| Registered Mail | 9208 8000 0000 0000 0000 00 | 22 digits |
| Priority Mail Express | 9270 1000 0000 0000 0000 00 or EA 000 000 000 US | 22 digits or 13 characters |
| Priority Mail Express International | EC 000 000 000 US | 13 characters |
| Priority Mail International | CP 000 000 000 US | 13 characters |
Some business shippers produce domestic numbers longer than 22 digits, because Publication 199 allows serial numbers of several lengths. They track the same way. Every service in this table includes tracking, which is a separate feature from delivery speed; our explainer What Is USPS Tracking? covers what the service records.
What If a USPS Tracking Number Starts With 420?
A number that starts with 420 followed by five or nine digits isn’t the tracking number itself. “420” is the GS1 routing identifier, and the digits after it are the destination ZIP Code, which the barcode holds in front of the tracking number.
This usually happens when someone scans the label barcode with a phone or handheld scanner instead of reading the printed digits. Drop the 420 and the ZIP Code, and the remaining number, normally starting with 92 to 95, is the one to enter at USPS.com. If you’d rather scan than type, our USPS tracking QR code tips explain how the label and receipt codes work.
What Do International USPS Tracking Numbers Start With?
International USPS items use the Universal Postal Union’s S10 format: two service letters, eight serial digits, one check digit and the country code “US.” The final “US” means the item was mailed in the United States.
- E as the first letter points to express items such as Priority Mail Express International (EC, or EA for some domestic Priority Mail Express labels).
- C points to parcels such as Priority Mail International (CP is common).
- R points to Registered Mail items.
- L points to tracked small packets.
A code that ends in a different country code, such as CN or GB, was mailed from that country and handed to USPS for delivery in the U.S. You can usually track it at USPS.com once it arrives, and on the origin postal service’s site before that.
How Can You Tell a USPS Number From Another Carrier’s?
A domestic USPS package number is all digits. If your number contains letters at the start but doesn’t end in a two-letter country code, it isn’t a USPS number.
| What you see | Likely carrier |
|---|---|
| 22 digits starting 92, 93, 94 or 95 | USPS domestic |
| Two letters, nine digits, “US” | USPS international or Priority Mail Express |
| Starts with “1Z” | UPS |
| Two letters, nine digits, another country code | A foreign postal service, delivered by USPS in the U.S. |
If you aren’t sure which carrier has your package, the sender or retailer’s shipping email will name it. For UPS numbers, use UPS tracking rather than USPS.com.
Where Do You Find the Number on Your Label or Receipt?
The tracking number is printed directly under the barcode on the label, listed on a Post Office receipt next to the service you bought, and saved in the order history or confirmation email when you buy postage online. Our guide to finding your USPS tracking number from receipt paperwork shows which line to read on a counter slip.
If you print your own shipping labels, the number is also stored in the account you bought them from. Once you’ve found it, our page on USPS tracking history explains how to read every scan, and the complete guide to USPS tracking covers USPS.com, the app and text tracking.
Does Where You Buy the Label Change the Tracking Number?
Yes, at least the first two digits. A label bought at a Post Office counter or kiosk typically starts with 95, while one bought online through USPS or an online postage provider typically starts with 94. The tracking itself works the same either way.
Buying online also changes the price you pay. ParcelPath is free, with no subscription or per-label fee, and gives up to 89% off USPS and up to 85% off UPS; its eCommerce shipping tools suit online sellers. To see what your package would cost, compare USPS and UPS prices in the ParcelPath rate calculator. For an overview of every USPS service, see our USPS shipping guide.
Frequently Asked Questions
Does a USPS tracking number starting with 9400 mean Ground Advantage?
Not necessarily. Under USPS Publication 199, the “94” shows the label came from a USPS API, PC Postage provider or postage meter, and the service is coded in the next three digits. Many online labels start with 9400, but the USPS.com tracking page is the reliable way to confirm the mail class.
How many digits does a USPS tracking number have?
Most domestic USPS tracking numbers are 22 digits, starting with 92, 93, 94 or 95. Some business labels are longer because Publication 199 allows several serial-number lengths. International and some Priority Mail Express items use a 13-character format of two letters, nine digits and “US.”
Why does my USPS tracking number start with 420?
Because you’re seeing the full barcode data. “420” is a routing identifier followed by the destination ZIP Code, and the actual tracking number comes after it. Remove the 420 and the five or nine ZIP digits, then enter the remaining number, usually starting with 92 to 95, at USPS.com.
What does a USPS tracking number starting with 95 mean?
A number starting with 95 usually means the postage was bought at a USPS Retail counter or a self-service kiosk at a Post Office. USPS Publication 199 assigns the 95 channel identifier to those retail sales. The digits that follow identify the service, so check USPS.com to see which mail class it is.
Do USPS tracking numbers ever contain letters?
Only in the 13-character international format, which starts with two letters and ends in a country code such as “US,” and in some Priority Mail Express labels that start with EA. A domestic package number with letters, such as one starting “1Z,” belongs to another carrier; 1Z numbers are UPS.
Sources
- USPS Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide (PostalPro)
- USPS FAQ: USPS Tracking, The Basics
- USPS FAQ: How to find your tracking number
- S10 (UPU standard) tracking identifiers
Part of our USPS Tracking guide. Related: USPS Tracking and Delivery, USPS Tracking Not Updating, USPS Tracking Not Updating After Drop Off.
