GTIN Check Digit Calculator and UPC, EAN-13, ITF-14 Converter

How it works

Enter the digits printed under the barcode, one number per line. The tool tells the type from the length: 12 digits is a UPC-A, 13 an EAN-13, 8 an EAN-8 and 14 a GTIN-14 case code. Take the UPC-A 036000291452: the tool confirms that the final 2 is the correct check digit, gives the EAN-13 form 0036000291452 (a leading zero is added, the check digit stays the same) and builds the case code 10036000291459 with indicator digit 1. An EAN-13 that does not start with 0, such as the German number 4006381333931, has no UPC-A form, and the tool says so instead of inventing one. If you only have the first 11 or 12 digits, choose "No check digit yet": 03600029145 becomes 036000291452. When a check digit does not match, the line shows which digit it should be and the corrected number. If a UPC copied out of Excel lost its leading zero, the digit-count warning on that line tells you.

This tool is also known as gtin check digit calculator, upc to ean, upc to ean converter, ean 13 to itf 14, ean 13 to gtin 14, upc check digit calculator, gtin 14 calculator.

What is GTIN?

GTIN (Global Trade Item Number) is the umbrella name GS1 uses for product numbers. UPC-A, EAN-13, EAN-8 and GTIN-14 are the 12, 13, 8 and 14-digit spellings of the same numbering system, so any of them can be padded with leading zeros to 14 digits and stored in one database column. When Amazon, Google Merchant Center or an ERP asks for a GTIN, this is what it means, and the last digit is always the check digit.

What is Check digit?

The check digit is the single rightmost digit of a barcode number. It is computed from the other digits and carries no information of its own; its only job is to catch typing and reading errors. A scanner recomputes it on every read and rejects the code if it does not match, which catches any single wrong digit and most swaps of two neighbouring digits. Because the rule works on digits only, alphanumeric codes such as SKUs have no GS1 check digit.

What is ITF-14 (DUN-14)?

ITF-14 is the chunky, bearer-barred barcode printed on corrugated shipping cases; the 14-digit number it carries is a GTIN-14, also called DUN-14 in Latin America and older documents. Its first digit is the indicator, which tells the packaging level; the next twelve usually come from the item's UPC-A or EAN-13, and the last is a freshly calculated check digit. It is read in warehouses and distribution centres, not at the till.

What is the difference between UPC and EAN?

They are two spellings of one system. UPC-A has 12 digits and is used in the United States and Canada; EAN-13 has 13 digits and is the standard almost everywhere else. Any UPC-A becomes a valid EAN-13 by adding a leading 0, and the check digit stays the same because the zero adds nothing to the weighted sum. The reverse is limited: only EAN-13 numbers that start with 0 have a UPC-A form, so a European product starting with 400 or 300 has none. Modern point-of-sale scanners read both; the difference matters when an import form, a marketplace listing or an older system insists on exactly 12 or exactly 13 digits.

How the check digit works, and the mistake that breaks most numbers

Every GS1 number (EAN-8, UPC-A, EAN-13, GTIN-14) ends in a digit calculated the same way. Leaving the check digit out, multiply the digits from right to left by 3, 1, 3, 1 and so on, add the products, and the check digit is whatever brings the total up to the next multiple of ten. For 03600029145 the weighted total is 58, so the check digit is 2 and the full UPC-A is 036000291452. A till scanner runs the same sum on every read and refuses a code whose last digit does not fit.

The usual failure is not the check digit but the leading zero. Spreadsheets store 036000291452 as a number and silently drop the zero, leaving 36000291452, eleven digits that no scanner or marketplace accepts. The tool flags such a line as "11 digits not recognised". Format the Excel column as Text and paste again, or add the zero by hand; you do not need a new check digit, because leading zeros do not change the sum.

Case code: an ITF-14 built from the item, or a separate number?

A case of 12 or 24 identical items needs its own number so that a warehouse never confuses the case with a single unit. The common method is to take the item's EAN-13 or UPC-A, drop its check digit, put an indicator digit in front and recalculate the last digit: UPC-A 036000291452 becomes 10036000291459 with indicator 1. That 14-digit number is printed on the corrugated case as an ITF-14 barcode; in Latin America the same number is often called DUN-14.

The indicator separates packaging levels: one case size can use 1, a second size of the same item takes 2, and so on up to 8. Indicator 9 is reserved for variable-measure goods sold by weight, so the tool only offers 1 to 8. The derivation is optional: a brand owner may give a case a completely separate GTIN. When you paste a GTIN-14, the tool also shows the item number obtained by removing the indicator and recalculating the check digit, which is only the real item number if the case code was derived that way.

• Single item scanned at the till → UPC-A in the US and Canada, EAN-13 elsewhere
• Case of the same item, warehouse and shipping → ITF-14 / GTIN-14 with an indicator digit
• Marketplace or ERP field asks for 14 digits → GTIN-14 with leading zeros (00036000291452)

Frequently asked questions

How do I calculate a GTIN check digit?

Enter the number without its last digit and choose "No check digit yet". The tool weights the digits 3 and 1 from the right, adds them and appends the digit that brings the total to the next multiple of ten. It works for GTIN-8, GTIN-12 (UPC), GTIN-13 and GTIN-14.

How do I convert a UPC to an EAN-13?

Put a 0 in front of the 12-digit UPC-A; the check digit does not change. 036000291452 becomes 0036000291452. The reverse only works for an EAN-13 that starts with 0; a number starting with 400 or 300 has no UPC-A form.

How do I turn an EAN-13 into an ITF-14 (GTIN-14) case code?

Drop the EAN-13 check digit, add an indicator digit (usually 1) in front and recalculate the 14th digit. For 4006381333931 the result is 14006381333938. Change the indicator option to number other packaging levels of the same item.

If the check digit is correct, can I print the number on my product?

No. A valid check digit only proves the number is well formed, not that it belongs to you. In the US and Canada, UPC numbers for retail are licensed from GS1 US; other countries have their own GS1 office. This tool checks and converts numbers you already have; it does not issue new ones.

My 8-digit number starts with 0. Is it a UPC-E?

It may be: small US packs often carry a compressed 8-digit UPC-E. The tool reads 8 digits as an EAN-8 and does not expand UPC-E to 12 digits, so take the full UPC-A from the pack or from the supplier before converting.