Labsco
inference-sh logo

youtube-thumbnail-design

โ˜… 582

by halt-catch-fire ยท part of inference-sh/skills

YouTube thumbnail design with specific dimensions, contrast rules, and mobile preview optimization. Covers safe zones, text placement, face expression psychology, and A/B testing. Use for: YouTube thumbnails, video cover images, click-through optimization. Triggers: youtube thumbnail, thumbnail design, video thumbnail, click through rate, ctr optimization, youtube cover, video cover image, thumbnail maker, thumbnail tips, youtube design, video preview image

๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅโœ“ VerifiedFreeQuick setup
๐Ÿงฉ One of 7 skills in the inference-sh/skills package โ€” works on its own, and pairs well with its siblings.

YouTube thumbnail design with specific dimensions, contrast rules, and mobile preview optimization. Covers safe zones, text placement, face expression psychology, and A/B testing. Use for: YouTube thumbnails, video cover images, click-through optimization. Triggers: youtube thumbnail, thumbnail design, video thumbnail, click through rate, ctr optimization, youtube cover, video cover image, thumbnail maker, thumbnail tips, youtube design, video preview image

Inspect the full instructions your agent will receiveExpand

This is the exact playbook injected into your agent when the skill activates โ€” shown here so you can audit it before installing. You don't need to read it to use the skill.


name: youtube-thumbnail-design description: "YouTube thumbnail design with specific dimensions, contrast rules, and mobile preview optimization. Covers safe zones, text placement, face expression psychology, and A/B testing. Use for: YouTube thumbnails, video cover images, click-through optimization. Triggers: youtube thumbnail, thumbnail design, video thumbnail, click through rate, ctr optimization, youtube cover, video cover image, thumbnail maker, thumbnail tips, youtube design, video preview image" allowed-tools: Bash(belt *)

Install the belt CLI skill: npx skills add belt-sh/cli

YouTube Thumbnail Design

Create high-CTR YouTube thumbnails with AI image generation via inference.sh CLI.

Specifications

SpecValue
Dimensions1280 x 720 px (minimum)
Recommended1920 x 1080 px
Aspect ratio16:9
Max file size2 MB
FormatsJPG, GIF, PNG

The 120px Test

Your thumbnail appears at roughly 120px wide on mobile โ€” that's how most viewers first see it.

At 120px, viewers must be able to identify:

  1. The mood/emotion (from colors and expression)
  2. The general subject (from composition)
  3. The text (if any โ€” only if large enough)

Test: view your thumbnail at 120px width. If it's a muddy blur, redesign.

Safe Zones

Copy & paste โ€” that's it
โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”
โ”‚                                             โ”‚
โ”‚   โœ… SAFE FOR TEXT AND KEY ELEMENTS         โ”‚
โ”‚                                             โ”‚
โ”‚                                             โ”‚
โ”‚                                             โ”‚
โ”‚                                             โ”‚
โ”‚                                       โ”Œโ”€โ”€โ”€โ” โ”‚
โ”‚                                       โ”‚ โฑ โ”‚ โ”‚ โ† Timestamp overlay
โ”‚                              โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ดโ”€โ”€โ”€โ”˜ โ”‚    (bottom-right)
โ”‚   โ”Œโ”€โ”€โ”€โ”€โ”                     โ”‚  DURATION    โ”‚
โ”‚   โ”‚ CH โ”‚ Chapter marker      โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”‚
โ””โ”€โ”€โ”€โ”ดโ”€โ”€โ”€โ”€โ”ดโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜
     โ†‘ Bottom-left: chapter/progress markers

Avoid placing critical elements in:

  • Bottom-right corner (video duration timestamp)
  • Bottom-left corner (chapter markers, progress bar)
  • Extreme edges (cropping varies by device)

Color Strategy

High-Contrast Pairs That Work

CombinationMoodBest For
Yellow + BlackUrgency, attentionTech, business, lists
Red + WhiteEnergy, excitementEntertainment, reactions
Blue + OrangeProfessional contrastEducation, tutorials
Green + WhiteGrowth, moneyFinance, success stories
Purple + YellowPremium, creativeDesign, art, creativity
White + DarkClean, minimalLuxury, minimalist channels

Color Rules

  • Background and text/subject should be complementary or high-contrast
  • Avoid same-temperature colors touching (red on orange = mud)
  • Use 3 colors maximum per thumbnail
  • Saturate more than real life โ€” thumbnails compete with bright UI

Text on Thumbnails

When to Use Text

  • Lists/numbers: "7 Tips", "Top 10"
  • Strong opinions: "STOP Doing This"
  • Results: "$10K in 30 Days"
  • Comparisons: "vs" between two things

When NOT to Use Text

  • The video title already says it (redundant)
  • The emotion/visual tells the story
  • You can't make it large enough to read at 120px

Text Rules

RuleReason
Max 6 wordsReadability at thumbnail size
Min 60pt equivalentMust be legible at 120px width
Bold sans-serif fontThin fonts disappear at small sizes
Contrast stroke/shadowEnsures readability on any background
No small textIf it's not readable small, cut it

Face Expression Psychology

Thumbnails with faces get higher CTR than faceless thumbnails. Expression matters:

ExpressionCTR ImpactBest For
Surprise/shockHighestReaction, reveal, discovery content
CuriosityHighTutorial, how-to, tips
ExcitementHighUnboxing, reviews, announcements
Concern/worryMedium-highWarning, mistake, problem content
ConfidenceMediumExpert advice, authority content
NeutralLowestAvoid unless your brand is minimalist

Face Composition Rules

  • Face should fill 30-50% of the thumbnail
  • Eyes looking toward the text or subject (directs viewer attention)
  • Eyes looking at camera = connection. Eyes looking at object = curiosity.
  • Place face on one side (usually left), text or subject on the other
Copy & paste โ€” that's it
# Generate a face-forward thumbnail
belt app run falai/flux-dev-lora --input '{
  "prompt": "close-up portrait of a man with genuinely surprised expression, mouth slightly open, raised eyebrows, looking at camera, left side of frame, vibrant teal background, dramatic rim lighting, YouTube thumbnail style, high contrast, cinematic",
  "width": 1280,
  "height": 720
}'

# Generate a face-looking-at-subject thumbnail
belt app run bytedance/seedream-4-5 --input '{
  "prompt": "person looking amazed at a glowing holographic chart showing upward growth, dramatic blue and green lighting, right side profile view, dark background, tech aesthetic, high energy",
  "size": "2K"
}'

Thumbnail Patterns by Content Type

Tutorial / How-To

Copy & paste โ€” that's it
belt app run falai/flux-dev-lora --input '{
  "prompt": "overhead flat lay of organized workspace with laptop showing code editor, colorful sticky notes, coffee cup, clean bright background, professional setup, tutorial style composition, warm lighting",
  "width": 1280,
  "height": 720
}'

Before/After

Copy & paste โ€” that's it
belt app run falai/flux-dev-lora --input '{
  "prompt": "split composition, left side dark and messy disorganized desk, right side bright clean organized minimalist workspace, dramatic contrast between chaos and order, clear dividing line in center, high contrast",
  "width": 1280,
  "height": 720
}'

Product Review / Comparison

Copy & paste โ€” that's it
belt app run falai/flux-dev-lora --input '{
  "prompt": "two products facing each other with dramatic lighting and sparks between them, competition battle concept, dark background with colorful rim lighting, versus comparison style, high energy, product photography",
  "width": 1280,
  "height": 720
}'

Listicle / Number

Copy & paste โ€” that's it
belt app run falai/flux-dev-lora --input '{
  "prompt": "dynamic arrangement of 7 different colorful objects floating in space against dark gradient background, each item distinct and clearly separated, energetic composition, vibrant saturated colors, studio lighting",
  "width": 1280,
  "height": 720
}'

A/B Testing

Test one variable at a time:

VariableTest A vs B
Face vs No faceSame composition, with/without person
ExpressionSurprise vs curiosity
Color schemeWarm vs cool palette
Text vs No textWith/without text overlay
BackgroundBright vs dark
CompositionLeft-facing vs right-facing subject
Copy & paste โ€” that's it
# Generate variant A
belt app run falai/flux-dev-lora --input '{
  "prompt": "..., bright yellow background, ...",
  "width": 1280, "height": 720
}' --no-wait

# Generate variant B (same prompt, different background)
belt app run falai/flux-dev-lora --input '{
  "prompt": "..., dark navy background, ...",
  "width": 1280, "height": 720
}' --no-wait

Thumbnail Checklist

  • 1280x720 minimum (1920x1080 preferred)
  • Under 2MB file size
  • Passes the 120px squint test
  • No critical elements in bottom-right (timestamp) or bottom-left (chapter)
  • Max 3 colors, high contrast
  • Text (if any) is max 6 words, bold, with contrast stroke
  • Face expression matches content energy (if applicable)
  • Doesn't duplicate the video title
  • Stands out from surrounding thumbnails (check your niche)
  • Works on both light and dark YouTube backgrounds

Related Skills

Copy & paste โ€” that's it
npx skills add inference-sh/skills@ai-image-generation
npx skills add inference-sh/skills@image-upscaling
npx skills add inference-sh/skills@prompt-engineering

Browse all apps: belt app store