Barcode Test: Check a Barcode Image Before You Print

Test a barcode image before you print it. The barcode test reads the code on your device, measures its quiet zones against the GS1 minimums, its module size and its contrast, checks the check digit and shows the data. It is a pre-check of an image, not verification, and it gives no grade.

Barcode image

This is a pre-check of an image. It is not ISO/IEC 15416 or ISO/IEC 15415 verification and gives no grade: a grade needs a calibrated barcode verifier measuring the printed barcode.

Result

Choose an image: the result shows the quiet zones, the module size, the contrast, the check digit and the data, measured on your device.

How to Test a Barcode Before You Print It

Test the exact image you will print, then print one copy and scan it before you print many.

  1. Export the barcode as you will print it, as a PNG at its print resolution or as an SVG, with its margins.
  2. Choose the file above: the test reads the code and draws its outline and quiet zones over the image.
  3. Fix any quiet zone marked narrower than the minimum, a low contrast or a wrong check digit, and test again.
  4. Print one copy at full size and scan it with a phone or the barcode scanner before printing the batch.

What the Barcode Test Measures

The test measures the image you choose, in modules, the width of the narrowest bar or square of the code.

Quiet Zones

The blank margin on each side is measured in modules up to the first dark mark or the edge of the image, and compared with the GS1 minimum for the type. A dashed line on the image shows where the minimum ends.

Module Size

The module is shown in pixels and, when the file states its resolution, in millimeters. Below 2 pixels per module the measurements are rough, so test a larger image.

Contrast

The brightness of the bars and of the background is shown in percent of white, with their difference. A difference under 20 points is pointed out: the generator refuses colors below that.

Check Digit and Data

The check digit of EAN, UPC and ITF-14 numbers and of the GTIN or SSCC in a GS1-128 is checked, and the data is shown as text, hex and ASCII with any control characters named.

Data Matrix and QR Code Patterns

For Data Matrix, the solid L finder pattern, the alternating clock track and, in symbols of 32 × 32 modules and larger, the alignment patterns are drawn over the image. For QR Code, the three finder patterns at its corners are drawn.

Barcode Quiet Zone Requirements

Every barcode needs a blank margin, the quiet zone, so the scanner can find where the code starts and ends; the GS1 General Specifications set these minimums in modules.

Minimum quiet zones in the GS1 General Specifications R26.0
BarcodeLeftRightSection
EAN-13117§5.2.3.4, Table 5-11
UPC-A99§5.2.3.4, Table 5-11
EAN-877§5.2.3.4, Table 5-11
UPC-E97§5.2.3.4, Table 5-11
GS1-1281010§5.4.4.2
ITF-141010§5.3.2.2
GS1 DataMatrix1 on every side1 on every side§5.6.2
GS1 QR Code4 on every side4 on every side§5.7.4.2

Other types, such as Code 39 or Aztec, have their minimums in their own ISO specifications; the test shows their measured quiet zones without a minimum.

Barcode generator draws every barcode with at least these quiet zones and lets you widen them.

Barcode Test vs Barcode Verification

Verification measures a printed barcode with a calibrated verifier and gives a grade; this test measures an image on your screen and gives none.

What a Verifier Measures

A verifier scans the printed symbol under set light and aperture and grades it from 4 to 0 under ISO/IEC 15416 for linear barcodes or ISO/IEC 15415 for 2D codes. The GS1 General Specifications (§5.12.5) describe the method and note that grades of 1.5 or better gave acceptable scanning in practice.

When You Need a Verified Barcode

When a retailer or a trading partner asks for a verification report, have the printed barcode measured with a verifier or by a verification service. This test helps you get the file right before that.

Frequently Asked Questions

Is This an Online Barcode Verifier?

No. It measures an image of a barcode and gives no grade, while verification measures the printed barcode with a calibrated verifier under ISO/IEC 15416 or 15415. Use it to catch problems in the file before printing.

Is the Barcode Test Free?

Yes. It needs no account, and the image is read and measured in your browser without being uploaded.

How Wide Should the Quiet Zone Be?

It depends on the type: an EAN-13 needs 11 modules on the left and 7 on the right, a UPC-A 9 on each side, a GS1-128 and an ITF-14 10, a GS1 QR Code 4 and a GS1 DataMatrix 1 on every side. Wider is fine.

Why Is the Module Size Shown in Pixels?

An image has no size on paper until it is printed: the pixels are what the test can measure. When the file states its resolution, as a PNG from the generator does, the size in millimeters is shown too.

Can the Test Check a Printed Barcode?

Only through a flat, sharp scan or photo of it, and the result describes that picture: light, focus and the camera change the contrast. Printing defects that a verifier finds, such as bars that spread, are not measured.

What Contrast Does a Barcode Need?

As much as possible: dark bars on a white background. The test points out a difference under 20 points of brightness, the level at which the generator refuses colors; a verifier measures the real symbol contrast of the print.

Related Barcode Tools