What characters can Code 128 encode?

All 128 ASCII characters: uppercase and lowercase letters, digits, and punctuation. The encoder automatically switches between subsets to keep the symbol as short as possible.

Code 128 or Code 39 — which should I use?

Code 128 in almost every new project. It is denser, supports lowercase letters, and includes a check character. Code 39 mainly persists for legacy systems that cannot read anything else.

Is there a length limit?

There is no hard limit in the specification, but readability degrades as symbols get very wide. Keep payloads under about 20-25 characters for handheld scanning.

Can I generate hundreds of these at once?

Yes, with a CSV upload on the bulk generator. Paste or upload one value per row and download the whole batch.

Is Code 128 better than Code 39?

For most internal use, yes. Code 128 is roughly 30% narrower for the same data, supports lowercase and full ASCII, and carries a check character. Code 39 only wins where legacy hardware demands it.

How long can a Code 128 barcode be?

There is no hard limit in the specification, but past about 20-25 characters the symbol becomes impractically wide for a standard label. Split long data or use a 2D symbology.

What is the difference between Code 128 and GS1-128?

GS1-128 is Code 128 with a leading FNC1 character and standardised application identifiers, which makes the data readable by trading partners rather than only by you.

Can Code 128 encode lowercase letters?

Yes, through subset B. The encoder picks the subset automatically based on your value.

What module width should I print at?

0.25 mm to 0.5 mm suits most handheld and fixed-mount scanners. Go wider for long-range or damaged-label environments.

Barcode generator / Code 128

Code 128 Barcode Generator

Generate Code 128 barcodes free online. Encode letters, numbers and symbols of any length, then download as PNG or SVG. No signup, no watermark.

Barcode data

Any length. Letters, digits, and common punctuation are all supported.

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 128 used for?

Code 128 is the workhorse of internal logistics. Unlike retail symbologies it is variable-length and encodes the full ASCII set, so it can carry SKUs, serial numbers, batch codes, location IDs, and mixed alphanumeric strings such as SKU-48812-A. Its high density means it also stays compact even with longer payloads.

Pick Code 128 when the barcode is for your own warehouse, asset tags, shipping labels, or a WMS integration — anywhere you control both the printer and the scanner and do not need a GS1 retail number.

Warehouse & inventory labels
Shipping and carrier labels
Asset tagging and serial numbers

Code 128 specification

Character set	Full ASCII 0-127 via subsets A, B and C
Length	Variable — no fixed digit count
Check character	Modulo-103, added automatically
Density	Highest of the linear symbologies; subset C packs 2 digits per module pair
Quiet zone	10 modules either side, minimum 6.4 mm at typical label sizes
Typical bar height	12-32 mm depending on scan distance
Best for	Internal SKUs, serials, shipping and asset labels

How to generate a Code 128 barcode

1
Type or paste the value to encode — letters, digits and punctuation are all accepted.
2
Keep the payload as short as the process allows; every extra character widens the symbol.
3
Set a bar height of roughly 15% of the symbol width for reliable handheld scanning.
4
Download SVG for label templates, PNG for screens and documents.
5
Scan the printed label from the distance and angle your operators actually use.

Troubleshooting scan failures

The barcode is too wide for the label

Shorten the payload, switch to all-digit values so subset C double-density applies, or reduce module width slightly — not below 0.25 mm for handheld scanners.

Scanner returns extra or missing characters

Usually a keyboard-wedge configuration issue rather than the symbol. Check the scanner's suffix settings and character set, then rescan.

Thermal labels stop scanning after a few weeks

Direct thermal fades with heat and light. Use thermal transfer with a resin ribbon for anything that lives longer than a few months.

Spaces in your value cause mismatches downstream

Code 128 encodes spaces faithfully, so the mismatch is in your data. Trim leading and trailing whitespace before generating.

Need hundreds of codes at once?

Upload a CSV and get every barcode or QR code back in one download — plus editable dynamic QR codes with scan analytics, and an API for programmatic generation.

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