The Short Answer: 800px Wide, Sliced Into 1280px Chunks
For WEBTOON Canvas — the platform most people mean when they say webtoon — the upload spec is a fixed 800px width, with each image file no taller than 1280px. An episode is a stack of these slices, read top to bottom as one continuous scroll. Files must be JPG or PNG and stay under the per-file size cap (2MB has been the long-standing limit), so a typical episode is 20–60 slices exported at 800px wide. The height of the whole episode is effectively unlimited; only the individual slice height is capped. If you remember one number from this whole guide, make it 800 — every other spec hangs off that width. Always confirm against the platform's current requirements before a big upload, because caps do get revised.
Draw Bigger Than You Publish
800px is a display spec, not a drawing spec. Draw at 800px and your art has zero headroom: no room to crop, no room to reuse a panel in print, and any resampling shows immediately. Working webtoon artists draw at 1.5×–2.5× final width and downscale on export. The most common working canvas sizes are 1600px and 2000px wide, at 300 DPI if print is ever a possibility. Downscaling sharpens lines; upscaling ruins them, and that asymmetry is the entire argument. The same logic applies to length: rather than one monstrous 60,000px-tall working file that fights your software's memory limits, most creators work in page-sized chunks — 1600×20000px is a popular ceiling in Clip Studio Paint — and slice at export time.
Platform-by-Platform Webtoon Canvas Sizes
The three destinations that matter for most creators, and what each one wants. Specs shift occasionally, so treat this as the map and the platform's uploader as the territory.
WEBTOON Canvas
Width: exactly 800px. Slice height: up to 1280px per image. Format: JPG or PNG, under the per-file cap. Episodes assemble from dozens of slices. Thumbnails have their own specs (square and banner crops), so save a flattened high-res master to crop them from.
Tapas
Tapas displays comics at up to 940px wide, so it will accept the 800px exports you made for WEBTOON — they simply render slightly smaller than native. Publishing the same episode to both platforms from one 1600px master, exporting 940px for Tapas and 800px for WEBTOON, is the standard mirroring workflow.
Print conversion
Vertical scroll does not reflow into pages automatically. If print is on your roadmap, draw with loose panel groupings that can re-stack into page grids, keep your working file at 300 DPI, and leave real margins. A 1600px-wide working canvas at 300 DPI translates to roughly 5.3 inches of printable width — close to a standard manga trim size, which is not a coincidence in how the format evolved.
Safe Margins and Vertical Pacing
The webtoon canvas is narrow and phones clip the edges of attention, not pixels — readers scroll fast, and anything near the left/right border gets skimmed. Keep dialogue and faces inside the middle ~80% of the 800px width, which means roughly 80px of breathing room per side. Vertical spacing is your pacing tool: small gaps (~100–200px at export size) read as continuous action, large gaps (600–1000px) read as a beat of silence or a scene change, and the biggest gaps right before a reveal create the scroll-drop effect the format is famous for. Panel borders are optional in webtoon; many creators float art directly on the background color and let spacing do the work that gutters do in a printed comic.
Slicing an Episode Without Cutting a Face in Half
Because each uploaded image maxes out at 1280px tall, a finished episode must be cut into slices — and a bad auto-slice will bisect a speech bubble or a character's face. Slice at natural gaps between panels, not at fixed intervals. Clip Studio Paint's webtoon export, Photoshop's slice tool, and free web slicers all allow manual cut lines; put every cut inside empty gutter space. This is also the argument for planning gaps at multiples that cooperate with 1280: if your panel groups run 1000–1200px tall with clear space between them, slicing becomes trivial instead of surgical.
The Shortcut: Generate Panels Already Sized for Vertical Scroll
If the drawing itself is the bottleneck, an AI comic tool can hand you panels already proportioned for the format. Comicory's webtoon mode generates panels in vertical-friendly ratios with consistent characters across the episode, and exports a long-scroll PNG that's ready to slice — so the canvas math above becomes a five-minute export step instead of a setup project. You still control pacing by adjusting the gaps; the tool handles the width, resolution, and character consistency.