What is the difference between EAN-13 and UPC-A?

EAN-13 is the 13-digit international retail barcode; UPC-A is the 12-digit North American version. UPC-A is actually EAN-13 with a leading zero, so this tool encodes them with the same underlying bars.

How is the check digit calculated?

For EAN-13 each digit is multiplied by 1 or 3 by position, summed, and the check digit is whatever makes the total a multiple of 10. UPC-A uses the same modulo-10 idea with the weights swapped. The tool computes and verifies it for you.

When should I use Code 128 versus Code 39?

Code 128 set B is compact and encodes the full printable ASCII range, ideal for shipping and internal labels. Code 39 is older, less dense, and limited to digits, uppercase letters, and a few symbols, but is supported by virtually every scanner.

Why is the output SVG instead of PNG?

SVG is vector, so the barcode stays perfectly sharp at any size — crucial because a blurry or anti-aliased barcode can fail to scan. You can paste the SVG anywhere or rasterise it to PNG at the exact resolution you need.

Is my data sent anywhere?

No. The barcode is built from the published encoding tables directly in your browser. Nothing about the value you enter leaves your device.

Barcode Generator (EAN / Code 128 / Code 39 / UPC)

A barcode encodes a number or short string as a pattern of bars and spaces that a scanner can read. This generator builds the four most common 1D symbologies — EAN-13, UPC-A, Code 39, and Code 128 — straight from their official encoding tables and renders them as crisp, scalable SVG.

How it works

Each symbology has its own rules:

EAN-13 / UPC-A use three character sets (L, G, and R patterns of seven modules each). The first digit selects a parity pattern that interleaves L and G codes across the left half, and a modulo-10 weighted check digit guards against misreads. The tool computes that check digit and verifies any you supply.
Code 39 maps each of 43 characters (0-9, A-Z, and - . space $ / + %) to a fixed pattern of nine elements, framed by * start and stop characters with a narrow gap between symbols.
Code 128 set B encodes ASCII 32-126, prefixes a Start-B symbol, and appends a modulo-103 weighted check symbol before the stop pattern, giving a dense, reliable code.

The resulting bit pattern is drawn as black rectangles in an SVG with a proper quiet zone on each side and a human-readable caption underneath.

Tips and example

For EAN-13, enter the 12 significant digits and let the tool append the 13th. For example 590123412345 becomes the valid code 5901234123457.
Always keep the quiet zone (the blank margin) — the tool includes one, so do not crop tightly when you paste the SVG.
Vector SVG stays sharp at any size; if you need a PNG, export the SVG at high resolution rather than scaling a small bitmap, which would soften the bars and risk scan failures.
Everything is computed locally, so it is safe for internal SKUs and confidential product numbers.