This page contains practical steps you can follow when printing barcode labels and packaging artwork containing an embedded barcode design, to ensure reliable, standards-compliant output. Getting a barcode to scan at the checkout or in the warehouse starts long before ink hits substrate. Poor print quality, incorrect colours, or truncated quiet zones can all be avoided before production when you plan ahead.
Start with the right artwork
Barcode symbols should always be generated from high-resolution or vector sources. Raster images at 300 dpi may suffice for small labels, but vector formats such as SVG or EPS will scale without losing edge definition and are strongly preferred, especially in cases where symbol size might change.
Common source-file mistakes:
| Problem | Why it matters | Better practice |
|---|---|---|
| JPEG or low-resolution PNG | Compression artefacts blur bar edges | Use vector format or raster graphics at ≥600 dpi resolution |
| Screenshots from web pages, copy-pasting of images | Unknown resolution, possible moiré patterns results in unscannable barcode. Potential softening of bar edges | Download barcode image files directly, if supplied, or export from native barcode generation software, if self-generating images |
| Stretched or skewed symbols | Alters bar width ratios | Lock aspect ratio; resize proportionally |
If you are preparing artwork from a purchased GTIN and the supplier did not give you an image of the barcode symbol you can either: purchase a barcode image from a reputable barcode service provider or you can try make the image yourself. If making your own barcode image, generate it from the full GTIN-13, GTIN-12, or GTIN-14 number, instead of re-typing from a printed sample. A single digit error will produce a barcode symbol that will not scan correctly, and in some cases a digit transpodition can produce a valid symbol encoding an entirely different GTIN.
For background on file formats, see barcode image formats.
Colour and contrast
Black bars on a white background remain the safest and most widely supported color combination. The human eye can distinguish many colour pairs, but a scanner relies on reflectance differences at its specific light wavelength—typically in the red or near-infrared range.
Key points for colour selection if you are departing from black bars white background paradigm on your product packaging:
- Bars should use dark, non-reflective colours: black, very dark blue, dark brown, or dark green.
- Backgrounds should be light and reflective: white, pale yellow, or light orange.
- Avoid red bars on a white background, or black bars on a red background—red appears dark to many scanners and can merge with the bars.
- Metallic substrates (silver, gold foil) often reflect the scanner beam unpredictably; over-print with an opaque white or light ink first if possible.
The barcode colour legibility simulator can help you preview whether a chosen colour pair is likely to cause problems before you go to press. It is not a substitute for physical verification, but it catches obvious mismatches early.
GS1 guidelines note that while alternative colours are permitted, the symbol must still meet minimum reflectance specifications in the scanning environment 12. When in doubt, default to black bars on white background.
Quiet zones and bar height
The quiet zone (or light margin) is the blank space to the left and right of the barcode. It separates the symbol from other print elements and allows the scanner to recognise where the data begins and ends. Truncating this space is a surefire way to cause scanning failures.
Minimum quiet zone requirements vary by symbology:
| Symbology | Minimum quiet zone | Approximate width at 100% magnification |
|---|---|---|
| EAN-13 | 11 modules left, 7 modules right | 3.63 mm left, 2.31 mm right |
| UPC-A | 9 modules on each side | 2.97 mm on each side |
| EAN-8 | 7 modules on each side | 2.31 mm on each side |
| UPC-E | 9 modules on left, 7 on right | 2.97 mm left, 2.31 mm right |
| GS1-128 (Code 128) | 10× the X-dimension on each side | - |
| ITF-14 (on corrugated) | 10 mm on each side | - |
The X-dimension is the nominal width of the narrowest bar. In retail POS symbols, the allowed range is typically 0.264 mm to 0.660 mm depending on the specific standard and application 2.
Bar height is equally critical. Reduced-height (truncated) bars may scan on flatbed readers in controlled conditions but often fail at angled checkout lanes or with handheld guns. Official GS1 guidelines recommend preserving full bar height unless the packaging geometry makes it genuinely unavoidable—and even then, truncation should stay within specified limits 13.
For a broader checklist of artwork placement issues, see packaging artwork checks.
Print process considerations
If you are producing your own barcode labels or product packaging with embedded barcode symbol, note that different printing methods introduce different risks. Adjust your preparation and proofing accordingly:
Digital (toner or inkjet)
- Toner can fuse with slight spread; inkjet may wick on absorbent stock.
- Test at the intended print resolution and speed.
- UV-cured inkjet on non-porous films may need adhesion promoters or a white base.
Flexography
- Plate squeeze and ink viscosity cause bar growth or shrinkage.
- Use barcode-specific plate screening and 1-up test pulls to measure actual X-dimension.
- Reverse-print (white bars on coloured background) is risky; consult your trade house.
Offset lithography
- Generally excellent edge definition, but dot gain still occurs.
- Specify barcode film or CTP curves that compensate for expected gain on the target substrate.
Thermal transfer or direct thermal (labels)
- Ribbon and substrate pairing affects edge sharpness.
- Direct thermal labels can darken with heat or age; consider application environment.
Screen printing, pad printing, laser etching
- Often used for industrial or promotional items.
- Verify that line weight consistency meets the minimum X-dimension for the target scanner pool.
Regardless of process, always generate a proof on the actual—or identically specified—substrate. Paper proofs on office stock do not predict behaviour on metallised film, textured cartonboard, or translucent bottles.
Testing on the actual material
A barcode that verifies perfectly on a glossy proofing paper may fail once printed on the production material. Test print and scan under conditions that match the supply chain:
- Print a sample using the production press, inks, substrate, and drying/curing cycle.
- Measure the X-dimension, bar height, and quiet zones with a calibrated magnifier or verifier.
- Scan with the same equipment type used downstream: POS laser, 2D imager, fixed-mount tunnel, or warehouse RF gun.
- Check at the intended orientation and any likely misalignment (tilted, curved, or in a shrink-wrap distortion).
- Store a retained sample for dispute resolution if downstream rejects occur.
GS1 symbol specification documents provide formal verification grades based on ISO/IEC 15416 or ISO/IEC 15415, but even a basic scan-test across multiple devices catches most field failures 12. Barcode service providers can provide verification tests against product artwork and packaging.
For guidance on scanner types and compatibility considerations, see scanner compatibility. Or consider purchasing a barcode verification test from a barcode service provider.
Common print defects to watch for
| Defect | Typical cause | Remedy |
|---|---|---|
| Bar growth (increased width) | Ink spread, excessive pressure | Adjust anilox/ink; use bar-width reduction in pre-press |
| Bar shrinkage | Under-inking, plate wear | Replate; increase ink density |
| Voids or spots in bars | Contamination, damaged plate, toner flaking | Clean or replace plate/roller; check substrate coating |
| Quiet zone encroachment | Artwork error, trimming variance | Add buffer in design; control die-cutting tolerances |
| Ghosting or show-through | Ink transparency, thin substrate | Increase opacity; change substrate or add backing |
| Excessive gloss differential | Varnish over barcode only | Keep varnish off symbol area; use matte overall coating |
Summary checklist for self printing
You can use this interactive checklist before releasing barcode artwork to production, confirm:
- Source file is vector or high-resolution raster, generated from the correct GTIN
- Colour combination tested for scanner reflectance (if not using black on white)
- Quiet zones meet symbology minimums and are clear of text, graphics, or trim lines
- Bar height preserved; truncation only if unavoidable and within standard limits
- X-dimension appropriate for the intended scanning environment
- Proof printed and scanned on actual production substrate and equipment
- Print process variables (dot gain, spread, substrate absorption) compensated in pre-press
Following these steps reduces rejections, avoids costly reprints, and ensures your barcode performs from the first scan to the last.
Footnotes
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GS1 UK, Barcoding: Getting It Right (PDF). https://www.gs1uk.org/sites/default/files/GS1-UK-barcoding-getting-it-right.pdf ↩ ↩2 ↩3
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GS1 General Specifications, Release 24.0 (PDF). https://www.gs1.ch/sites/default/files/2024-02/GS1%20General%20Specifications%2001_24_0.pdf ↩ ↩2 ↩3
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GS1 US, Guideline for Bar Code Symbol Placement (PDF). https://documents.gs1us.org/adobe/assets/deliver/urn:aaid:aem:30071c02-969b-4b61-acc1-a44373c44ec1/Guideline-Bar-Code-Symbol-Placement.pdf ↩