バーコードのサイズと倍率: 適切な寸法設定
Barcode sizing rules — X dimension, magnification factors (80%-200%), height requirements, and minimum sizes by symbology and application.
Barcode Size & Magnification: Getting the Dimensions Right
Barcode sizing directly affects scan reliability. Too small, and scanners cannot resolve the individual bars. Too large, and the barcode may not fit the label or exceed the scanner's field of view. GS1 and ISO standards define precise sizing rules.
X Dimension: The Foundation of Barcode Sizing
The X dimension is the width of the narrowest bar or space; the basic unit of barcode width." data-category="Barcode Anatomy & Structure">module in the barcode. Every other dimension scales proportionally from X. For example, an EAN-13 at X = 0.33mm (100% magnification) is 37.29mm wide. At X = 0.264mm (80%), it is 29.83mm wide.
EAN/UPC Magnification
GS1 defines magnification as a percentage of the nominal (100%) size:
| Magnification | X Dimension | EAN-13 Width | EAN-13 Height |
|---|---|---|---|
| 80% (minimum) | 0.264mm | 29.83mm | 20.74mm |
| 100% (nominal) | 0.330mm | 37.29mm | 25.93mm |
| 150% | 0.495mm | 55.94mm | 38.90mm |
| 200% (maximum) | 0.660mm | 74.58mm | 51.86mm |
Most retail products use 80-100% magnification unless the package is large.
Minimum Size by Application
| Application | Minimum X | Reason |
|---|---|---|
| Retail POS (EAN/UPC) | 0.264mm (80%) | Omnidirectional scanner specs |
| Supply chain (GS1-128) | 0.495mm | Handheld scanner at arm's length |
| Warehouse (Code 128) | 0.25mm general | Close-range scanning |
| Corrugated (ITF-14) | 0.635mm | Flexographic print tolerance |
| Healthcare (Data Matrix with GS1 AIs for pharma and food traceability." data-category="2D & Matrix Symbologies">GS1 DataMatrix) | 0.254mm | Clinical scanner specs |
Height Requirements
Bar height affects scanning reliability for linear barcodes. Taller bars give the scanner more chances to find a clean scan line.
- EAN-13: Minimum 18.28mm at 80% (22.85mm at 100%)
- GS1-128: Minimum 31.75mm
- ITF-14: Minimum 32mm
- Code 128: General guideline: height should be at least 15% of symbol width or 6.35mm, whichever is greater
Never truncate (reduce height below specification) without understanding the scan reliability impact.
2D Barcode Sizing
For 2D barcodes, the X dimension determines the module (cell) size:
| Symbology | Minimum Module Size | Practical Size |
|---|---|---|
| Data Matrix | 0.254mm (10 mil) | 0.33-0.76mm |
| QR Code | 0.33mm for print | 0.66mm+ for consumer scanning |
| PDF417 | 0.17mm (6.7 mil) | 0.25-0.50mm |
Sizing Mistakes
- Undersized barcodes: The most common error. Results in scan failures
- Truncated height: Reducing bar height to save space degrades read rates
- Disproportionate scaling: Stretching width without height (or vice versa) distorts the encoding
- Inconsistent magnification: Different barcodes on the same label at different magnifications creates confusion
Sizing Workflow
- Determine the symbology required
- Identify the minimum X dimension for your application
- Calculate the resulting barcode width and height
- Verify the barcode fits on the label with adequate quiet zones
- If too large, consider a different symbology or label size
- Never go below the minimum X dimension specified for your application