Barcode reference · QR Studio

1. A practical barcode selection workflow

1

Identify the destination system.

Ask where the scan result goes: retail point of sale, warehouse management, shipping, publishing, postal routing, ticketing, or an internal database.

2

Confirm the required standard.

Use the exact symbology and identifier format requested by the retailer, carrier, customer, or standards body.

3

Validate the data.

Check length, allowed characters, check digit, prefixes, Application Identifiers, and separator rules before generating artwork.

4

Design within the standard.

Adjust permitted scale, height, colors, and readable text without changing encoded bar geometry.

5

Test the final production sample.

Scan the actual printed label, package, carton, ticket, or mail piece with representative equipment.

2. Common barcode families

UPC-A

Numeric · 12 digits
Retail products in North America. Includes left, center, and right guard patterns plus prescribed readable-digit grouping.

UPC-E

Numeric · compressed UPC
Compact retail symbol for eligible number systems. Not every UPC-A value can be converted to UPC-E.

EAN-13

Numeric · 13 digits
International retail trade-item symbol. The final digit is a calculated check digit.

EAN-8

Numeric · 8 digits
Smaller retail identifier for packages where EAN-13 is impractical.

Code 128

Broad character support
High-density general-purpose linear barcode for logistics, assets, documents, and internal systems.

GS1-128

GS1 structured data
Code 128 using FNC1 and GS1 Application Identifiers for logistics and supply-chain data.

Code 39

Uppercase and symbols
Simple industrial symbology used for identification, manufacturing, and legacy workflows.

ITF-14

Numeric · 14 digits
Trade-item identification on corrugated cases and shipping containers. Often printed with bearer bars.

GS1 DataBar

Compact GS1 family
Retail-oriented symbols that can encode GTINs and, in expanded variants, additional attributes.

Postal

Country-specific data
Routing symbols such as Intelligent Mail, Royal Mail, Japan Post, and others with strict input rules.

ISBN / ISSN

Publishing identifiers
Book and periodical identifiers represented through EAN structures, optionally with 2- or 5-digit add-ons.

2D symbols

Data Matrix, QR, PDF417
Useful when a linear symbol cannot carry enough data or when the required standard specifies a 2D carrier.

Do not substitute similar-looking formats

UPC-A, EAN-13, Code 128, GS1-128, and ITF-14 may all display numeric data, but they are not interchangeable. The scanner may decode the bars while the receiving business system still rejects the identifier.

3. UPC and EAN retail structure

UPC and EAN symbols use prescribed bar patterns, check digits, quiet zones, and human-readable placement. The digits around the bars are not merely decorative labels.

UPC-A anatomy

The number-system digit is printed outside the left guard pattern.
Two groups of five digits sit beneath the left and right data halves.
The check digit is printed outside the right guard pattern.
Start, center, and end guard bars extend lower than ordinary data bars.
The total encoded value contains 12 digits, including the check digit.

Do not manually move guard bars

Use the app's typography and digit-spacing controls only for readable text. The encoded bars and guard positions must remain tied to the UPC/EAN module pattern.

Add-on symbols

Two- and five-digit add-ons are separate supplementary symbols used with publications and some retail workflows. They require their own spacing and data rules. Do not append the extra digits directly to the main UPC or EAN value.

4. Check digits and data validation

A check digit is calculated from the preceding digits and helps detect common data-entry or scanning errors. It does not prove that the identifier was legitimately assigned or belongs to a particular company.

Format	Typical validation	Frequent error
UPC-A	Exactly 12 digits with a valid final check digit.	Entering 11 digits but assuming every generator adds the check digit automatically.
EAN-13	Exactly 13 digits with a valid final check digit.	Using an internal SKU instead of an assigned retail identifier.
ITF-14	Exactly 14 digits and valid check digit.	Printing a consumer-unit GTIN where a carton-level identifier is required.
Code 128	Characters must be supported; the symbol includes an internal checksum.	Confusing plain Code 128 with GS1-128 structured data.
GS1-128	Valid Application Identifiers, field lengths, FNC1, and identifier check digits.	Typing visible parentheses as encoded data or omitting separators after variable fields.

When a generator offers automatic check-digit calculation, confirm whether the input expects the digit to be included or omitted. Different libraries and workflows handle this differently.

5. Module width, bar height, and quiet zones

A linear barcode is built from narrow modules. Wider bars are exact multiples of the narrowest module. The module scale control changes the width of the encoded geometry; bar height changes the vertical dimension permitted by the chosen symbology.

Module scale

Increasing scale makes every bar and space wider. It usually improves tolerance, but the symbol occupies more horizontal space.

Bar height

Taller bars provide a larger vertical target for linear scanners. Do not reduce height below the requirements of the applicable standard.

The quiet zones are the blank areas immediately before the first bar and after the last bar. Text, borders, label edges, graphics, and crop marks must stay out of these areas.

Scale the entire symbol proportionally.

Keep left and right quiet zones clear.

Do not compress a barcode to make it fit.

Allow for trimming and label-placement tolerance.

Test curved or flexible packaging on the real surface.

Measure the symbol after final artwork placement.

6. Human-readable text and fonts

Readable text allows a person to enter the value when scanning is unavailable. It does not replace the bars. Use a clear font, sufficient size, and spacing that preserves the prescribed grouping of the selected symbology.

Keep all characters legible at final print size.
Do not let digits touch bars or enter quiet zones.
Preserve UPC/EAN outside digits and group structure.
Avoid condensed, decorative, script, or highly stylized fonts for operational labels.
Confirm that exported SVG text either embeds correctly or remains editable in your production workflow.

Font changes do not change the encoded value

The scanner reads bar geometry. Typography controls only the visible text, provided it does not overlap or obscure the symbol.

7. Color, substrate, and print method

Scanners need a strong optical difference between dark bars and the light background. Black bars on white are the safest baseline. Dark navy, deep green, or another very dark color may work when contrast remains high.

Avoid these combinations

Red, orange, or pale bars that may appear weak under red-light scanners.
Dark bars on a dark or transparent background.
Metallic, reflective, holographic, or heavily textured areas.
Reversed white bars on black unless the complete workflow explicitly supports it.
Low-resolution printing that causes narrow spaces to fill in.

Thermal printers, inkjet, offset, flexographic, laser, direct marking, and screen printing all behave differently. Calibrate the design to the actual press or printer rather than judging only a desktop proof.

8. Exporting clean barcode artwork

SVG

Preferred for packaging and layout software. The app exports bars as filled vector rectangles, not strokes, so line-weight changes cannot alter the encoded widths.

PNG

Good for digital workflows and label systems that require raster images. Choose enough pixels for the intended print size.

JPG

Use only when required. Compression may soften narrow edges, especially after repeated saves.

PDF

Convenient for proofing and print placement. Confirm output dimensions and avoid unintended fit-to-page scaling.

Illustrator checklist

Keep bars as filled shapes with no stroke.
Do not use effects, rounded corners, blur, or path simplification on the bars.
Scale uniformly from a corner or enter one proportional percentage.
Keep readable text separate from encoded bar geometry.
Export a proof and compare it with the original generated value.

9. Verification and production approval

A phone scan is a useful first test but not a complete barcode verification process. Professional verification measures properties such as symbol contrast, modulation, defects, decodability, quiet zones, and dimensional accuracy under controlled conditions.

1

Confirm identifier ownership and data.

Make sure the number is assigned for the intended product, location, shipment, or asset.

2

Generate and validate.

Use the correct symbology, length, check digit, and structured fields.

3

Place at final dimensions.

Preserve quiet zones, ratio, readable text, and production tolerances.

4

Print through the real process.

Use the actual substrate, printer, ink, finishing, and label applicator.

5

Scan and verify.

Use representative scanners and professional verification when acceptance or compliance is critical.

10. Troubleshooting common barcode failures

Problem	Likely cause	Correction
Value rejected after a successful scan	Wrong symbology, invalid identifier, bad check digit, or unsupported data format.	Validate against the receiving system's exact specification.
Bars look correct but do not scan	Insufficient quiet zone, low contrast, scaling distortion, or narrow spaces filling in.	Restore dimensions and print a larger, higher-contrast proof.
UPC-A readable digits look wrong	Generic centered text replaced the retail layout.	Restore outside digits, two five-digit groups, and guard extensions.
Scanner reads a different type	Scanner auto-discrimination or an incorrect generator selection.	Confirm symbology settings in both the generator and scanner.
Carton barcode scans inconsistently	Corrugate distortion, flexo gain, curvature, damage, or inadequate size.	Increase tolerance and verify an actual production carton.

Choose the barcode standard before choosing the style.

The right barcode is the one your workflow can actually read.