A practical workflow for comic slices, thumbnails, profile visuals, and preview images that need to stay readable on mobile.
When a WEBTOON CANVAS creator is preparing an episode slice, square series thumbnail, or vertical thumbnail before publishing, image compression and sizing means making each file fit its role without hurting readability. Start with original art you have rights to use, make upload copies from that source, then preview the WEBTOON CANVAS episode or thumbnail before publishing.
Give Each WEBTOON Image One Job
An episode slice is part of the vertical reading rhythm. A square series thumbnail helps people recognize the series. A vertical thumbnail gives WEBTOON more promotional space. An episode thumbnail appears beside a specific update. A profile image or banner represents the creator, not one panel. Treating all of these as the same export is how readable lettering, crop safety, and file limits begin to fight each other.
Episode slices
Protect panel order, speech bubbles, line edges, and scroll pacing.
Series thumbnails
Design square and vertical discovery art separately instead of cropping one image everywhere.
Preview visuals
Keep title cards, promo art, and profile images honest to the comic tone.
Rights checks
Use original, licensed, or permitted artwork and avoid copied characters or logos.
Use Current WEBTOON Limits As Guardrails
WEBTOON materials currently reference episode image limits such as 800x1280 px maximum dimensions, 2 MB per sliced or unchanged image, 20 MB total, and 100 images per upload. The same materials explain that images over the maximum dimensions may be optimized, sliced, reduced, or changed. That is why creators who want more control should slice a long-scroll master into clean upload copies before publishing.
Thumbnail requirements are different. WEBTOON CANVAS currently lists square series thumbnails at 1080x1080 and under 500 KB, vertical series thumbnails at 1080x1920 and under 700 KB, and episode thumbnails with their own recommended size and file rules. Because platform screens can change, use the official upload form as the final rule.
| WEBTOON CANVAS image role | Where it appears | What it should communicate | Main quality or upload risk | What to preview before publishing |
|---|---|---|---|---|
| Episode slice | Vertical episode reader | The next beat of the story without broken flow. | Text becomes soft, panel cuts feel abrupt, or file weight triggers optimization. | Phone-size reading, bubble clarity, panel order, and slice boundaries. |
| Long-scroll master | Your art app, not the final upload | A safe high-quality source for corrections. | Uploading the master directly may give WEBTOON less predictable slicing control. | Exported slices compared against the master. |
| Square series thumbnail | Series discovery surfaces | Main character, tone, and visual identity. | Over-small text, busy backgrounds, or a file above the thumbnail limit. | Crop, face readability, and file size in the current dashboard. |
| Vertical series thumbnail | Tall discovery placements | A poster-like promise for the series. | Using the square thumbnail crop and losing the character or title mood. | Top, center, and lower composition on mobile. |
| Episode thumbnail | Manage Series and episode lists | What this update contains. | A stale or misleading panel that does not match the episode. | Episode list, character expression, and safe file name. |
| Profile or promo image | Creator profile, posts, and external sharing | Creator identity or a rights-safe preview. | Private data, unauthorized logos, or copied artwork. | Permission, rating fit, and whether the image matches the comic. |
Compress Without Hurting The Comic
Compression should happen after the image role is clear. JPG is often practical for full-color scenes, painted backgrounds, gradients, and thumbnails that need smaller file weight. PNG is often safer for sharp line art, flat colors, title cards, and lettering-heavy images where edge artifacts would be obvious. Test one dialogue slice and one detailed art slice before batching the full episode.
Build A Repeatable Upload Routine
- Keep the original high-resolution comic master separate.
- Choose the image role before resizing or compressing.
- Slice episode art around reading beats, not random height marks.
- Export a JPG or PNG delivery copy for the role.
- Check speech bubbles, line art, gradients, and file size.
- Prepare square and vertical thumbnails as separate designs.
- Preview the episode, thumbnails, and rating-sensitive visuals before publishing.
FAQs About WEBTOON CANVAS Image Compression And Sizing
It is the process of making role-specific upload copies for episode slices, thumbnails, and creator visuals while preserving mobile readability, file limits, and rights-safe content.
An episode slice carries story flow inside the vertical reader. A thumbnail is discovery or episode-list art and needs a clearer crop, smaller file weight, and an honest visual hook.
WEBTOON creator materials explain that oversized images may be sliced, reduced, compressed, or changed. Creators who want more control should prepare compliant upload copies themselves.
Use JPG when a full-color scene needs smaller weight and PNG when lettering, flat color, or line art suffers from JPG artifacts. Always preview the result on mobile.
Use original artwork, licensed assets, or material you have permission to upload. Do not copy characters, panels, logos, screenshots, or another artist's work.
