Barcode questions and answers
Formats, sizes, files, printing and GS1 numbers, in plain words.
Choosing a format
Which barcode should I use?
For products sold in shops, EAN-13 (or UPC-A in the US and Canada) with a number from your GS1 Company Prefix. For cartons, ITF-14. For your own stock, assets and orders, Code 128. For a link people scan with a phone, QR Code. For small parts or GS1 data in little space, Data Matrix.
What is the difference between 1D and 2D barcodes?
Linear (1D) barcodes such as EAN-13 and Code 128 are rows of bars read across. 2D codes such as QR Code and Data Matrix are grids of cells that hold much more data in less space, but need a camera-based scanner.
Can I use Code 128 instead of EAN-13 on a product?
Not for selling in shops: checkout systems expect EAN-13 or UPC-A with a GS1 number. Code 128 is ideal for labels you scan inside your own business.
GS1 numbers
Do I need to buy barcodes?
You do not need to buy the image: you can draw it here for free. For products sold in shops you need the number, a GTIN from your own GS1 Company Prefix, which you license from your local GS1 office.
Does this site check that my GTIN is registered?
No. It checks the check digit, which catches typing mistakes, but it cannot see GS1 records. Ask your GS1 office or use its own lookup service.
How is a GS1 check digit calculated?
Starting from the digit next to the check digit and moving left, multiply the digits by 3, 1, 3, 1 and so on, and add the results. The check digit is the number you add to reach the next multiple of 10 (0 if the sum already is one).
Size, files and printing
Which file should I download?
SVG or PDF for print and packaging artwork: they are vectors and stay sharp at any size. PNG for label printers, office documents and websites; choose 600 dpi or more for print. Every PNG stores its resolution, so it prints at the size shown here.
What is the module width?
The width of the narrowest bar (or of one cell in a 2D code). Everything in the barcode is a multiple of it, so it sets the printed size. Change it here instead of stretching the image afterwards.
Why does my printed barcode come out a different size?
Usually the program you print from scaled it. Print at 100% or “Actual size”. The SVG stores its size in millimetres and the PNG stores its dpi, so programs that read them place them at the right size.
Why do you keep a blank margin?
Scanners need empty space on both sides of a linear barcode, and around a 2D code, to find where it starts and ends. Cropping it is a common reason a barcode will not scan.
Batches and labels
How should I lay out my CSV?
Put the barcode data in the first column. A second column, if present, is printed as a caption under each barcode, and a third column sets how many copies of that label to print (1 to 100). A header row is detected, and you can switch it on or off.
How many barcodes can I make at once?
Up to 1,000 rows and 3,000 labels per batch. For more, split the list and run it again; nothing is stored between runs.
My labels do not line up with the sheet. What can I do?
Print at 100% (“Actual size”), not “Fit to page”. Then print one page on plain paper with outlines on, hold it against a label sheet in front of a light, and adjust the margins of a custom sheet if your printer shifts the paper.
Scanning and privacy
Why does it ask for the camera?
The browser asks before any site can use the camera. The camera starts only when you press “Start camera”, and the picture is read frame by frame on your device. Press Stop or leave the page to turn it off.
Are my barcodes stored anywhere?
No. They are drawn in your browser and nothing you type is sent to a server. The page address holds the data of the barcode on screen so you can bookmark or share it; batch lists are never put in the address.
Which formats can it read?
EAN-13, EAN-8, UPC-A, UPC-E, Code 128 and GS1-128, Code 39, Code 93, ITF and ITF-14, Codabar, QR Code, Data Matrix, Aztec and PDF417.
Still have a question?
Each format has its own page with details and printing tips, starting with EAN-13 and Code 128. For anything else, use the contact page.
- GS1: How to calculate a check digit manually
The mod 10 method (weights 3 and 1) for GTIN, GLN and SSCC check digits, with a worked example.
- GS1 New Zealand: Guide to getting a barcode
An example from a GS1 office of how a brand gets its numbers and then makes the barcode.
- W3C: PNG specification, pHYs chunk
Where a PNG stores its print resolution, which this site writes into every PNG.