Barcode Verification Grades: What A to F and 1.5/06/660 Mean

Verification is not the same as "it scans"

A scanner is built to read imperfect barcodes. A verifier is a measuring tool: the GS1 General Specifications (section 5.12.5) describe it as an instrument that determines how well a symbol can carry and deliver its data. A barcode that scans on your phone or your own handheld may still have so little margin that a different scanner fails on it. The grade tells you how much margin there is.

GS1 also lists what a verifier doesn't do on its own:

• Most verifiers don't measure bar height.
• Without a link to a database, it can't confirm the number is the right one for the product.
• It doesn't check that the digits printed under the bars match the encoded data.
• It only grades the samples it's given, and a perfect symbol can still be scratched, frozen or soaked later.

That's why a GS1-style verification report also includes manual checks of size, quiet zones, placement and data. GS1 says a compliant verifier is one built to ISO/IEC 15426-1 for linear barcodes or 15426-2 for 2D codes.

What a verifier measures

For linear barcodes such as UPC, EAN, ITF-14 and GS1-128, the method is ISO/IEC 15416; as of October 2026, ISO lists the 2025 edition as current. The verifier records a scan reflectance profile, a graph of how much light comes back along a line across the bars, and grades it on these parameters:

The contrast thresholds come from GS1's 1D verification guideline, and the General Specifications make quiet zones a measured parameter for EAN/UPC, GS1-128 and ITF-14. Since the 2016 edition of ISO/IEC 15416, parameters are graded to one decimal place rather than in whole steps, according to Axicon, which sells barcode verifiers.

How the overall grade is calculated

GS1's guideline calls for at least ten scan lines spread over the height of the symbol. Each scan line gets the grade of its weakest parameter: Axicon's example is a symbol whose contrast alone holds every scan to a 3 while everything else scores 4. The overall grade is the average of the scan grades to one decimal place, and GS1 says that average is the only figure to use when deciding pass or fail.

The numeric grade maps to letters like this, as KEYENCE lays it out:

Worked example

Ten scans graded 2.3, 2.1, 1.8, 2.0, 1.2, 1.9, 2.2, 2.0, 1.6 and 1.9 add up to 19.0, so the overall grade is 1.9, a C. That passes a 1.5 requirement even though one scan scored a D. GS1's guideline has reports list each parameter at the lowest value seen across the scans, so this report might show modulation at 1.2. The overall grade still passes; the 1.2 just points to the weakest spot to improve.

Reading 1.5/06/660

A grade only means something together with how it was measured, so GS1 writes it as grade/aperture/light:

• 1.5 is the minimum overall grade.
• 06 is the measuring aperture in thousandths of an inch, here 6 mil (about 0.15 mm).
• 660 is the wavelength of the light in nanometers, which is red.

The aperture matters. GS1 notes that one smaller than specified exaggerates defects and one larger smooths them out, so a report measured with the wrong aperture is misleading. For 2D codes such as Data Matrix and QR, the method is ISO/IEC 15415, and GS1 adds the light angle when it isn't 45 degrees. An asterisk after a 2D grade flags extreme reflectance around the symbol, which GS1 says should usually count as a fail. QR sizing and testing are covered in the QR size and error correction guide.

GS1 minimum grades

GS1's symbol specification tables set a minimum for each barcode and scanning environment:

The ITF-14 exception exists because brown corrugated board reflects so little light that symbol contrast can't rise above grade 1, which caps the overall grade at 1.0. The ITF-14 guide covers printing on corrugate.

Treat these as floors. GS1's own report template notes that the assessment is against the minimum and that a barcode should exceed it to scan efficiently.

Common low grades and their causes

The General Specifications list typical causes and fixes:

• Low symbol contrast: a background that's too dark or glossy, bars that are too light, or contents showing through. Use a lighter or more opaque material, darker bars, or a white underlay.
• Decode failure: a wrongly encoded symbol or a miscalculated check digit, or bars so far off in width that the verifier sees the wrong number of elements.
• Low decodability: bar gain from ink spread, a barcode image that was rescaled in graphics software, or a stretched printing plate. Create the barcode at its final size and ask the printer about bar width reduction.
• Defects: a failed thermal print head element leaves a light line through the bars; ink spatter and voids also count.
• Quiet zone failure: a box drawn around the symbol, or a label edge too close.

The print guide explains how to avoid most of these before you print.

When you need a verification report

GS1's 1D verification guideline describes two common moments: testing barcodes at the packaging design stage, and testing a finished product before it ships, when the report may be needed to satisfy a customer. It also warns that a failed report on a finished product can be serious if customers refuse shipments over it. In practice:

• Your customer asks for it. Follow the grade, aperture and format in its vendor manual exactly.
• Before a long packaging run. Verify a press proof in its final form, on the real material and after any lamination. GS1 says to test see-through material on both a dark and a light backing and keep the worse result.
• Periodically. A report covers only the samples tested, not every label you print later.

GS1 says you or your printer can do the measuring with a compliant verifier, and the General Specifications note that most GS1 member organizations offer a verification service.

Plain Barcode's generator sets the X-dimension and bar height in millimeters and the quiet zone in modules, and warns when they fall outside GS1's ranges, but it can't grade a printed barcode. Neither can a phone.

Bottom line

A verification grade is a measurement, not a scan test: ten or more scan lines, each held to its weakest parameter, averaged to one decimal and reported with aperture and light, as in 1.5/06/660. Aim above GS1's minimum for your barcode type, and get a report whenever a customer requires one or before you commit to a long print run.