Question 1

What's the difference between Code 128, EAN-13, and UPC-A?

Accepted Answer

Code 128 is variable-length and encodes all 128 ASCII characters, used for internal inventory, shipping labels, and anywhere you control both the encoder and reader. EAN-13 (International Article Number) is 13 digits, the global retail product barcode standard outside North America. UPC-A is 12 digits, the North American retail product barcode. EAN-13 and UPC-A require registered prefixes from GS1 to be globally unique; Code 128 has no such restriction.

Question 2

When should I use QR vs a 1D barcode?

Accepted Answer

1D barcodes (Code 128, EAN, UPC) are fast to scan with laser scanners, work in low resolution, and have the long retail-industry history. QR codes store more data (URLs, vCards, contact info), are scannable from phones with cameras, and tolerate damage (error correction up to 30%). For physical retail point-of-sale, 1D is still standard. For marketing, menus, wifi sharing, or anything customers scan with phones, QR wins.

Question 3

What's the check digit and why does it matter?

Accepted Answer

EAN-13 and UPC-A end with a check digit calculated from the preceding digits. Its purpose is error detection, if a scanner misreads one digit, the check digit math fails and the scanner reports an error rather than accepting wrong data. You can either provide the check digit yourself or let the tool compute it. Common mistake: typing all 13 digits as data and then having the tool add another check digit, producing a 14-digit barcode that no scanner recognizes.

Question 4

What size should I print a barcode at?

Accepted Answer

The minimum 'X-dimension' (width of the narrowest bar) determines readability. For retail (EAN/UPC): 0.264 mm (10 mil) minimum, 0.33 mm (13 mil) recommended. Code 128: typical X = 0.3-0.4 mm. The whole barcode should be at least 80% of nominal size for reliable scanning. If you print smaller, scanners struggle especially at angles or distance. Always print test samples and scan with the actual hardware before mass printing.

Question 5

Why does my barcode include human-readable text?

Accepted Answer

Below most 1D barcodes is the encoded data in regular text. This is for fallback when the scanner fails (operator types the number manually), for visual verification by humans, and to comply with retail standards (EAN/UPC require it). The text isn't part of the scan, scanners read only the bars. You can hide the text in many tools for clean design work, but include it for any production use.

Question 6

Can I use barcodes for tracking outside of retail?

Accepted Answer

Absolutely. Common non-retail uses: warehouse inventory (asset tags), library books (Code 39 or Code 128 historically), event tickets, healthcare patient wristbands, parcel tracking (proprietary FedEx/UPS barcodes), license plates, books (ISBN encoded as EAN-13). The choice of format depends on what data you need encoded and what readers your scanners support.

Question 7

What's a 'quiet zone'?

Accepted Answer

The blank space on either side of a barcode required for scanners to detect where it starts and ends. Standard quiet zone: 10 times the X-dimension on each side. Crowding the barcode against other graphics or print elements breaks scanning. Always leave generous margin, a barcode without a quiet zone is unreadable even if the bars themselves are perfect.

Question 8

Is my data sent to a server?

Accepted Answer

No. Barcode rendering uses the bwip-js library running entirely in your browser. The text, numbers, or URLs you encode never leave your tab. Useful for generating barcodes for confidential inventory systems, internal asset tracking, or unreleased product codes.

Question 9

What standards does Barcode Generator validate against?

Accepted Answer

Barcode Generator checks compliance with ISO/IEC 15420 (Code 128), ISO/IEC 15419 (Barcode).

Question 10

What are the limitations of Barcode Generator?

Accepted Answer

Code 128 only, does not support QR, DataMatrix, or other 2D formats Print quality depends on output resolution Does not verify barcode readability

Symbology	Standard	Data Type	Typical Industry
Code 128	ISO/IEC 15417	ASCII Alphanumeric	Logistics / Shipping
EAN-13	ISO/IEC 15420	Numeric (13 digits)	Global Retail
UPC-A	ANSI MH10.8M	Numeric (12 digits)	US Retail
QR Code	ISO/IEC 18004	2D Multi-Data	Marketing / Mobile

Barcode Generator

What is Barcode Generator?

Frequently Asked Questions

Technical Deep Dive

Barcode Generator

Specialist Tool

Zero Setup

Private by Default

01 Barcode Specification Matrix

02 Generation & Verification Pipeline

Runs 100% in your browser

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