Online course thumbnails are the deciding factor between potential students clicking "Enroll" or continuing to scroll. A professional thumbnail signals quality, builds trust, and attracts more students to your course.
Course Thumbnail Specifications by Platform
| Platform | Size | Aspect Ratio |
|---|---|---|
| Udemy | 1920×1080 px | 16:9 |
| Teachable | 1280×720 px min | 16:9 |
| Thinkific | 1280×720 px | 16:9 |
| Coursera | 2400×1350 px | 16:9 |
| Kajabi | 1920×1080 px | 16:9 |
Elements of High-Converting Course Thumbnails
- Course topic or outcome clearly stated — "Python for Beginners", "Master Excel"
- Instructor photo (if well known or builds trust in your niche)
- Visual element representing the topic (code, spreadsheet, camera, etc.)
- Professional colour scheme consistent with your brand
- Clear, bold typography that reads at small preview size
Creating Course Thumbnails Free
Upload your background to imgresizr.com. Crop to 16:9 ratio and resize to 1920×1080px for maximum quality on all platforms. Add the course title in large, bold text using the Caption tool — left-aligned or centred works well. Add a professional headshot in one corner if appropriate. Include any certification badges or "bestseller" indicators if applicable. Download as JPG at 90% quality.
Thumbnail A/B Testing
- Create two versions — test with your email list or social media to see which gets more clicks
- Different colour schemes often produce dramatically different results
- With vs without instructor photo is worth testing for your niche
- Update thumbnails of existing courses every year — fresh looks increase re-purchases
Create professional course thumbnails at 1920×1080px for free at imgresizr.com — every major online learning platform ready.