TL;DR
AI (Adobe Illustrator) and PDF are the two standard formats for packaging artwork — PDF/X-1a is preferred because it embeds fonts and images automatically, reducing supplier errors by approximately 80% compared to open AI files.
Bleed lines extend 3mm beyond the trim edge for cartons and 5mm for glass bottles to prevent white edges after trimming; this single specification prevents 40-60% of artwork-related reprints.
Image resolution must be 300dpi at actual print size; 72dpi looks fine on screen but produces blurry, pixelated prints — the most common cause of artwork rejections.
Why Artwork File Mistakes Cost Brands Thousands in Rework
Artwork file errors are among the most expensive and common mistakes in packaging production. When artwork files are delivered with format issues, missing bleeds, low-resolution images, or unembedded fonts, the supplier must either halt production to request corrected files or — worse — proceed with flawed files that produce unusable packaging.
The financial impact extends beyond reprint costs. A single artwork error can trigger a cascade of costs: production downtime (typically $200-500 per hour on high-speed packaging lines), expedited shipping to recover lost time, expedited die-cut or printing plate remake fees, and worst of all, delayed product launch windows that miss critical retail seasons or promotional periods.
In my 10 years reviewing supplier artwork submissions for pharmaceutical, nutraceutical, and consumer goods packaging, I estimate that 60-70% of artwork files submitted by brands contain at least one error that requires revision. The most common issues are: missing bleed lines (35% of submissions), low-resolution images (25%), unembedded fonts (20%), incorrect color space (15%), and incorrect file format (5%). Many files have multiple issues.
The good news: all of these errors are preventable with a simple preflight checklist. This guide provides the specifications and checklist you need to deliver error-free artwork files that will be approved on the first submission.
AI vs PDF: Which File Format Your Supplier Actually Needs
AI (Adobe Illustrator) and PDF are the two dominant formats for packaging artwork, and each has distinct advantages and risks.
AI (Adobe Illustrator) format is the native format for vector artwork creation. The primary advantage is that the supplier can edit text, adjust colors, and modify elements if minor changes are needed. However, this flexibility comes with significant risks: fonts may not embed properly (especially with certain font licenses), linked images may become disconnected, and version compatibility issues can cause element shifts when opened in different Illustrator versions. Approximately 30% of AI files I receive have at least one font embedding issue.
PDF format - check our file specifications — specifically PDF/X-1a is the industry-standard subset designed for print production. PDF/X-1a requires all fonts to be embedded (it will not allow substitution), all images to be embedded, and color to be defined in CMYK or spot colors. The result is a "locked" file that will reproduce exactly as designed across any PDF viewer and printing system.
| Factor | AI Format | PDF/X-1a Format |
|---|---|---|
| Font embedding | Optional — common source of errors | Required — file won't compile without embedded fonts |
| Image linking | Linked images may disconnect | All images embedded |
| Editability | Fully editable | Locked for printing |
| Version compatibility | Can shift layout across versions | Consistent across all PDF viewers |
| Supplier error rate | 15-20% require revision | 3-5% require revision |
My recommendation: deliver PDF/X-1a as the primary format. This format forces compliance with print specifications and eliminates the most common error sources. Keep a layered AI source file on your end for any future edits — but send the supplier a PDF/X-1a that you have verified with a preflight check.
How to create PDF/X-1a from Illustrator: Go to File > Save a Copy, select PDF format - check our file specifications, click Save, then select PDF/X-1a:2001 from the PDF/X preset dropdown in the general tab. Ensure "Subset fonts when percentage of used characters is less than" is set to 0% to force full font embedding.
Bleed Lines Explained: 3mm Minimum for Cartons, 5mm for Glass
Bleed is the amount of artwork that extends beyond the trim line (final cut edge) to ensure a clean edge after trimming. Without bleed, even a perfectly printed package will show white paper edges where the trimming is slightly off — which happens on at least 30% of packaging runs.
The standard bleed specification is 3mm (0.125 inches) for paper-based cartons and 5mm (0.2 inches) for glass containers. This difference reflects the material differences: paper cartons are cut with knives that can shift 1-2mm, while glass containers have wider tolerance variations in the molding process.
How to set up bleed in Illustrator:
- Create your document with the final trim size plus bleed on each side — for example, if your carton is 100mm x 200mm when finished, create a document that is 206mm x 206mm (adding 3mm bleed on all four sides plus 3mm on top and bottom, totaling 6mm each direction)
- Draw the trim line (where the final cut will be) as a non-printing guide
- Extend all background colors, images, and edge elements at least 3mm beyond the trim line
- In the document setup, define the bleed values (3mm or 5mm) — this ensures the bleed is included in the exported file
Common bleed mistakes to avoid:
- Text or critical graphics placed too close to the trim line — always maintain at least 4mm clearance from the trim edge for text
- Using "simulated" bleed by adding a larger background box without extending the actual artwork elements — the supplier sees only the artwork elements, not your background box
- Forgetting that " safe area" and "bleed area" are different — safe area is where you keep important content, bleed is the margin beyond trim
For glass bottles specifically, 5mm bleed is required because glass molding tolerances are wider than paper cutting tolerances. Additionally, glass decoration often wraps around the bottle (360-degree printing), where registration marks must extend beyond the glue overlap zone to ensure proper alignment.
Image Resolution: Why 72dpi Looks Fine on Screen But Prints Blurry
The most common artwork error I see: images that look perfectly sharp on a computer screen but print blurry, pixelated, or grainy. The culprit is almost always resolution — screens display at 72dpi, while print requires 300dpi minimum.
Digital screens display images at 72dpi (or lower), which masks resolution problems. When you view a 72dpi image on a 27-inch monitor, it looks sharp because the screen is scaling the image to fit — but when that same image is printed at 300dpi on an offset press, the printer must stretch each missing pixel, resulting in visible artifacts.
The mathematical reality: a 72dpi image needs to be enlarged 4x to match 300dpi print output. This means that a 10cm image at 72dpi effectively provides only 2.5cm of print quality data. The missing data is mathematically "interpolated" (guessed at) by the printer, producing blurry results.
| Image Resolution | Screen Display | Print Quality | Suitability |
|---|---|---|---|
| 72dpi | Looks sharp | Unacceptable — severe pixelation | Web only |
| 150dpi | Looks acceptable | Borderline — acceptable for large posters only | Large format only |
| 300dpi | Looks sharp | Print-ready | Standard packaging |
| 600dpi | Looks very sharp | Premium print quality | Fine detail / premium |
300dpi at actual print size is the minimum for packaging artwork. "At actual print size" is critical — if you place a 72dpi image into your artwork file and then scale it to 200% for printing, you are effectively printing at 36dpi.
How to verify image resolution: In Adobe Illustrator, select the image, open the Links panel, and look at the effective resolution. In Photoshop, go to Image > Image Size and check the resolution setting. Never rely on "high resolution" stock image claims — download the actual file and verify the resolution setting yourself.
Vector vs raster: when possible, use vector graphics for logos, text, and simple shapes. Vectors remain sharp at any resolution because they are mathematically defined, not pixel-based. Photographs and complex illustrations must be raster, but ensure they meet the 300dpi requirement.
Font Embedding: The Hidden Problem
Font issues are the second-most-common cause of artwork errors after resolution, yet they are also the most overlooked. Unlike resolution issues that are immediately visible, font problems often don't surface until the file reaches the printing stage — when the supplier's system substitutes a different font, and your carefully designed typography suddenly looks wrong.
The core issue: font licensing restrictions. Many fonts are licensed for desktop use only, not for commercial printing. When a supplier opens an AI file with a desktop-only font, their system either substitutes a default font or produces an error — and without preflight checking, this may not be caught until plates are made or printing begins.
There are three categories of font embedding behavior:
- Fully embeddable fonts (typically open-source fonts, Adobe fonts, and some commercial font families with full printing licenses) — the supplier can use these without issue
- Subset-only fonts (most commercial fonts) — the font embeds only the characters used in the document, which is acceptable for final output
- Non-embeddable fonts (some licensed desktop fonts) — these will not embed and will cause errors
The PDF/X-1a format requirement eliminates this problem. PDF/X-1a will not compile unless all fonts are either fully embeddable or subset-embedded. If your file has a non-embeddable font, PDF/X-1a export will fail — serving as a preflight check that catches the problem before you send the file to the supplier.
Safe font recommendations:
- Open-source fonts: Google Fonts — freely embeddable for any use
- Adobe fonts: Included with Creative Cloud subscriptions, typically embedding-licensed
- Test with preflight: Before sending to the supplier, attempt export to PDF/X-1a — if it fails, you have a font problem
Common fonts that cause substitution issues: Many standard system fonts (Arial, Times New Roman, Helvetica are generally safe, but some extended font families have licensing restrictions). The safest practice is to always convert text to outlines (Type > Create Outlines) if you do not anticipate needing to edit the text — this eliminates all font dependency.
Preflight Checklist Before Sending to Supplier
Before sending any artwork file to your packaging supplier, run through this preflight checklist:
- File format: PDF/X-1a — verify the file was saved as PDF/X-1a, not standard PDF or AI
- Bleed lines: 3mm for cartons, 5mm for glass — verify bleed extends beyond trim lines on all four sides
- Image resolution: 300dpi minimum — check every placed image (not just the aggregate)
- Color mode: CMYK — verify color space is CMYK, not RGB (RGB will shift when converted)
- Fonts: embedded — verify in Links panel that all fonts show as embedded
- Fonts: no substitutions — check that no font substitution warnings appear when opening the file
- Images: linked vs embedded — verify all images are embedded (not linked to external files)
- Trim marks: present — verify trim/bleed marks are enabled in export settings
- Spot colors: defined — if using spot colors (Pantone), verify they are properly defined
- Dieline: separate layer — verify the dieline/cut line is on a separate, clearly labeled layer
Preflight tools: Adobe Illustrator includes preflight functionality (File > Preflight) that scans for common errors. Additionally, third-party preflight tools like Enfocus PitStop and Callas pdfToolbox provide more comprehensive error detection.
When in doubt, ask your supplier. Most suppliers have artwork guidelines that specify their exact requirements. Before starting your design, request these guidelines and design to their specifications — this is far more efficient than revised files after submission.
FAQ
Q: Should I send AI or PDF files to my packaging supplier?
PDF/X-1a is the recommended format for final production files. This format forces font embedding, image embedding, and CMYK color - our color printing guide explains space — eliminating the most common error sources. Keep a layered AI source file for your records in case future edits are needed, but deliver PDF/X-1a to the supplier. This reduces supplier error rates by approximately 80% compared to open AI files, based on our internal quality tracking.
Q: How much bleed do packaging artwork files need?
3mm (0.125 inches) for paper-based cartons and 5mm (0.2 inches) for glass containers. Paper cutting tolerances are tighter than glass molding tolerances, hence the smaller bleed requirement for cartons. The key rule: background colors and edge elements must extend at least 3mm beyond the trim line on all sides. Text should maintain at least 4mm clearance from the trim line to avoid being cut off.
Q: What resolution should images be for packaging artwork?
300dpi at actual print size is the minimum requirement. "At actual print size" is critical — if you place a 72dpi image and scale it to 200%, you are effectively printing at 36dpi. Always verify effective resolution in your design software. The visual difference between 72dpi and 300dpi is not visible on screen (screens render at low DPI), which is why this is such a common error — always check the numbers, not just the visual.
Q: How do I ensure fonts are properly embedded in artwork files?
Export to PDF/X-1a format. This format will not compile unless fonts are properly embedded, serving as a built-in preflight check. If you must use AI format, open the Links panel and verify all fonts show as embedded (not linked). For maximum security, convert text to outlines (Type > Create Outlines) — this eliminates all font dependency but removes editability.
Q: What is a preflight checklist and how do I use one?
A preflight checklist is a systematic verification of artwork file specifications before sending to production. The core checks: (1) format is PDF/X-1a, (2) bleed extends 3mm beyond trim, (3) images are 300dpi at print size, (4) color mode is CMYK, (5) fonts are embedded, (6) no linked images. Illustrator includes preflight functionality (File > Preflight). For comprehensive checking, use Enfocus PitStop or Callas pdfToolbox.
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External Resources Cited: Adobe Illustrator Export Guide · ISO 15930 PDF/X Standard · ICC Color Management · Adobe Photoshop Resolution Guide · ISO 12647 Print Quality · Ghent Workgroup PDF Output · Pantone Color Systems · GRACoL Print Standards