Why is Code 39 also called Code 3 of 9?

Each character is drawn with nine elements — five bars and four spaces — of which three are wide. The name describes that structure.

Can Code 39 encode lowercase letters?

Not in standard Code 39. Input is uppercased automatically. If you need lowercase or full ASCII, use Code 128 instead.

Do I need start and stop characters?

No. The required asterisk delimiters are added by the encoder, so enter only your data.

Is Code 39 accepted in retail?

No. Retail point of sale requires UPC-A or EAN-13. Code 39 is for internal and industrial use.

Why is Code 39 still used?

It is self-checking, needs no check digit, and is decoded by essentially every scanner ever made, which is why defence, automotive and healthcare standards still specify it.

Does Code 39 need a check digit?

No. The modulo-43 check digit is optional and only used where a standard such as HIBC or a customer specification asks for it.

Can Code 39 encode a space?

Yes, space is a valid character. Be careful with leading or trailing spaces, which are easy to introduce accidentally and hard to spot in the printed text.

What is Code 39 Extended?

A convention that encodes lowercase and control characters as two-character sequences. The scanner has to be configured for it, so avoid it unless a standard requires it.

Is Code 39 the same as Code 3 of 9?

Yes, the two names refer to the same symbology.

Barcode generator / Code 39

Code 39 Barcode Generator

Create Code 39 (Code 3 of 9) barcodes free online. Encode uppercase letters and digits, download as PNG or SVG. No account and no watermark.

Barcode data

Uppercase A-Z, digits 0-9, and - . $ / + % and space.

Bar height80px

Show number under barcode

PNG resolution Pro

Preview

No watermark, no signup, unlimited PNG downloads. Rendered in your browser — the value you type never leaves your device. Vector SVG and high-resolution PNG are included with Pro.

What is Code 39 used for?

Code 39, also written Code 3 of 9, is one of the oldest alphanumeric barcode symbologies still in daily use. It encodes uppercase letters, digits, and a small set of symbols, and every character is self-checking, which made it popular long before scanners got sophisticated.

It remains standard in defence and automotive supply chains, healthcare asset tracking, and older library and government systems. It produces wider symbols than Code 128 for the same data, so choose it when a downstream system explicitly requires Code 39 rather than by default.

Automotive & defence supply chains
Healthcare and lab asset labels
Legacy inventory systems

Code 39 specification

Character set	0-9, A-Z uppercase, space and - . $ / + %
Length	Variable
Check digit	Optional modulo-43, rarely required
Start/stop	Asterisk delimiters, added automatically
Density	Low — roughly 30% wider than Code 128 for the same data
Quiet zone	10 modules either side
Best for	Defence, automotive, healthcare and legacy scanners

How to generate a Code 39 barcode

1
Enter your value in uppercase — Code 39 has no lowercase characters.
2
Replace unsupported punctuation with hyphens or periods, which are in the character set.
3
Set bar height and download SVG for print or PNG for documents.
4
If your receiving system expects the asterisks, confirm whether it strips them automatically.
5
Test-scan on the oldest scanner in your fleet, since Code 39 is usually chosen for exactly that hardware.

Troubleshooting scan failures

Lowercase letters are rejected

Convert your value to uppercase. Full ASCII Code 39 exists but is an extension many scanners do not decode by default.

Scanner reports asterisks around the value

Those are the start and stop characters. Turn on the scanner's option to strip start/stop, or trim them in your software.

Symbol is too wide

This is inherent to Code 39. If your hardware supports it, move to Code 128 and the same value fits in roughly two thirds the width.

Occasional misreads on long values

Enable the optional modulo-43 check digit in your receiving system, or shorten the payload.

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