EAN-13 Barcode Generator

How thirteen digits fit into a twelve-digit symbol

An EAN-13 symbol is exactly 95 modules wide — a module being the width of its thinnest bar. A three-module guard pattern at each end and a five-module guard in the center frame two halves of six digits each, every digit occupying seven modules. Count that up and only twelve digits get bars of their own.

The thirteenth — the leading digit — is carried by a trick: the left-half digits can each be drawn from two different encoding alphabets, and the pattern of which alphabet is used across those six positions spells out the leading digit. Leading digit 0 uses a single alphabet throughout, which is why a UPC-A is literally an EAN-13 with a leading zero: same bars, same check digit. The right half uses a third alphabet, so a scanner always knows which half it entered first — EAN-13 scans upside down as reliably as right side up. The leading digit, having no bars, is printed to the left of the symbol inside the left quiet zone — the wider of the two margins. For the digits themselves, the breakdown panel above does the honest split: GS1 prefix, manufacturer + product region, check digit — and our 13-digit barcode explainer covers the numbering system in more depth.

Go deeper: EAN-13 structure explained takes that panel's engine apart, and its companion, how GTIN check digits are computed, works the arithmetic below on a fictional number as well as the cited one. The guides hub has the rest.

How the check digit works

Number the first twelve digits left to right and multiply them alternately by 1 and 3 (the second, fourth, sixth… digits get the 3). Sum the products; the check digit is whatever brings that sum up to the next multiple of ten.

The same sum, position by position

The table is the engine's own intermediate output for the cited vector, every figure interpolated. Weights anchor at the right — the digit just before the check digit always carries 3 — so the 3 lands on the even positions.

The products sum to 89; the next multiple of ten is 90; and 90 − 89 = 1, the digit the generator appends. A sum already ending in zero gets 0, not 10 — the difference is taken modulo ten.

The check digit catches every single-digit typo and most adjacent-digit swaps — that is its whole job. It is why this tool never silently replaces a wrong 13th digit: a mismatch usually means one of the other twelve digits is wrong, and "correcting" the check digit would turn a detectable error into a perfectly valid wrong number. To work the algorithm by hand on any GTIN length, use the check digit calculator.

Compute mode and verify mode: reading the note

The validator reads the mode off the digit count. It normalises first — spaces and hyphens are stripped, so the cited vector pasted as 400 6381-33393 1 becomes 4006381333931 — then enforces the length rule: 12 digits means compute, 13 means verify, any other count is refused with the count you entered. Last it reports what it did beneath the barcode, in its own words; read that note before you download:

• Twelve digits in — "You entered 12 digits — the check digit 1 was computed and appended, making 4006381333931."
• Thirteen digits in — "You entered all 13 digits — the check digit 1 was verified against the first 12 and is correct." — the only note that says anything about the number you were handed.

Anything outside those two lengths is refused before any arithmetic runs, and the message names the rule. GS1's published example GTIN-14, 09506000134352 — the carton code the ITF-14 generator uses as its example — pasted here produces: "A EAN-13 needs 12 digits (check digit computed) or 13 digits (check digit verified) — you entered 14." The cited X-check ISBN-10 0-8044-2957-X fails the character rule instead, because the X survives separator stripping: "A EAN-13 contains digits 0–9 only (spaces and hyphens are ignored)." The ISBN barcode generator understands that X and converts the number to its EAN-13 form.

What a mismatch looks like

A fictional corruption of the cited vector: position 5, a 3, becomes 5, giving 4006581333931 with the check digit untouched. The verifier recomputes from the first twelve and compares — expected 9, supplied 1 — so the number is invalid. In the generator that is an error, and no bars are requested:

The message names the required digit but never puts it in for you — 400658133393 followed by 9 would be a structurally valid number for the wrong item — so it offers only the honest options: fix the number, or hand over twelve digits to compute from.

Swapping two adjacent digits moves the 3-weight onto one and the 1-weight onto the other, so the sum changes by twice their difference. Swap positions 4 and 5 of the cited vector (6 and 3) and 4003681333931 is caught — expected 7, supplied 1. Swap positions 5 and 6 (3 and 8, which differ by 5) and 4006831333931 still verifies: twice 5 is 10, so the sum's last digit does not move. That is what "most adjacent swaps" means: strong evidence of a clean transcription, not proof.

The same twelve digits, read by the bulk validator

On this page twelve digits always mean "compute the thirteenth". The check digit calculator, which validates a pasted column of mixed GTIN lengths, cannot assume that: a twelve-digit line may be EAN-13 data awaiting its check digit, or a complete GTIN-12 — a UPC-A — with its check digit already in place. Its auto mode resolves the ambiguity openly in favour of the complete-number reading, because it is a validator first. Paste the cited data digits 400638133393 there and auto mode reads them as a GTIN-12, verifying the final 3 against the eleven before it: "Check digit should be 0, not 3." — the corrected 400638133390 offered in a separate field, the line itself left alone. In data-only mode the same line is GTIN-13 data: "Check digit 1 appended." completing 4006381333931, the number this generator produces. Neither reading is wrong; they answer different questions, which is why the mode is a visible switch rather than a guess. Bulk GTIN validation modes covers the statuses and the row cap.

Print-exact dimensions, from the GS1 specification

These figures come from the GS1 General Specifications (the standard behind GS1's EAN/UPC symbology page), as published by GS1 member organizations — the GS1 Sweden size guide and GS1 Ireland's EAN-13 specification:

37.29 mm is not an arbitrary number: 95 modules of bars plus 11 + 7 modules of quiet zone make 113 modules, and 113 × 0.330 mm = 37.29 mm. The downloaded SVG is deliberately a little wider: the leading digit is printed in a blank 12-module strip inside the left margin, so the file spans exactly 125 module widths, with more than double the minimum quiet zone on the left. That makes the print math exact — set the SVG's width to 41.25 mm (125 × 0.330 mm) and every module comes out at precisely 0.330 mm; any width from 33.00 mm (80%) to 82.50 mm (200%) stays inside the allowed magnification band. Scale width and height together, always.

Quiet zones die in Word documents because white margins look like wasted space: the image gets cropped tight, or text and table borders crowd against its edges, and a scanner can no longer find where the symbol begins. The margins are part of the barcode — keep the ones that ship inside the download.

Verified before you download it

Every barcode this page shows has passed three checks, and it is worth being precise about what they do and do not cover. First, structure: the input must be exactly 12 or 13 digits, nothing else. Second, the check digit: computed for you or verified against what you typed, with mismatches flagged, never repaired. Both checks happen before the drawing library receives the accepted payload, using this site's separately implemented and tested arithmetic. Third, the actual SVG is rasterized and decoded by ZXing, independently from JsBarcode; an unreadable or mismatched render is withheld. The PNG canvas is decoded separately before export. These checks cover generated files, not physical print quality. The methodology page documents the full boundary.

The SVG that verification protects is free — worth saying plainly, because vector export is a common paywall on barcode sites. What none of this can verify is print quality: ISO/IEC 15416 grades a printed symbol on contrast, defects, and decodability, and those depend on your printer, ink, and substrate. We check the math; only a verifier or a real scanner can check the optics — test the printed result before production.

A withheld barcode is reported under one of 2 reasons, each named in the generator:

• decode-failed — the bars could not be read.
• payload-mismatch — a different string was read.

One equivalence is accepted deliberately: an EAN-13 payload beginning with 0 is the same printed symbol as the 12-digit UPC-A without that zero. Take the cited UPC-A reference vector's data digits with a leading zero, 003600029145, whose EAN-13 form is 0036000291452: a reading of 036000291452 for it is correct. For the cited EAN-13 4006381333931, by contrast, a fictional misreading that drops the first digit, 006381333931, withholds the download. See how the verifier decodes what you see.

What the ZPL download carries

The ZPL option in the download menu is a text document of printer commands, not an image; the printer's own barcode engine draws the bars from it. The export insists on the full validated payload — handed the twelve data digits alone it refuses: “EAN-13 ZPL export needs the full 13-digit payload including the check digit, exactly as the generator produced it — received "400638133393" (12 characters).” Given 4006381333931 it verifies the check digit once more, then sends only the data digits, ^FD400638133393^FS, because the printer recomputes the thirteenth itself; the export's own note says so: “The ^FD data carries only the data digits — the printer recomputes the check digit and arrives at the same 1 for this EAN-13 that our validator already verified.” The rest of the document, and the EPS export's unit mapping, are explained in ZPL and EPS export explained.

EAN-13, GTIN-13, and the rest of the family

The number inside an EAN-13 symbol is a GTIN-13 — one member of the GTIN family this site's 13-digit barcode guide maps out. The same mod-10 arithmetic protects UPC-A (a 12-digit GTIN — a UPC-A with a leading zero is the EAN-13 form of the same number), ITF-14 carton codes (GTIN-14), and the Bookland EAN that carries ISBNs with a 978/979 prefix — the breakdown panel above recognizes those prefixes when you paste a book's number. And if you are still deciding whether your product needs a licensed number at all, start with Do I need a GS1 barcode? For items sold only inside your own store — deli counters, store-packed goods, internal SKUs — the in-store barcode guide explains the restricted-circulation prefixes built for exactly that.

EAN-13 FAQ

Verify before production: this tool checks the math, not the optics — always test the printed result with your own scanner. Everything runs locally in your browser. See the methodology page for how the verification layer works.