Best Aspect Ratio for YouTube Shorts: 9:16 Settings and Real Credit Costs
YouTube Shorts wants 9:16 at 1080x1920 and up to three minutes. Here is how duration drives cost, which VdoBloom models support vertical, and the per-second numbers.
The best aspect ratio for YouTube Shorts is 9:16 at 1080 × 1920 pixels, and the setting that matters almost as much is duration — Shorts accepts anything up to three minutes, which changes which AI model is worth paying for. YouTube will accept a square or even a landscape upload into the Shorts shelf, but only a true vertical frame gets the full-screen, edge-to-edge playback that Shorts was built around.
The rule YouTube actually applies
A video qualifies as a Short if it is 3 minutes or under and its frame is square or taller. That means 9:16, 4:5 and 1:1 all technically qualify. In practice only 9:16 is worth authoring, because anything shorter than full height leaves grey or blurred filler above and below your footage on a phone, and because YouTube’s own recommendation surfaces preview Shorts in a tall thumbnail that a square video fills badly.
There is a second playback context people forget: Shorts on a TV. There, a vertical video is pillarboxed with the channel information beside it. You cannot optimise for both, and you should not try — the phone is where the watch time is. Author 9:16.
Setting it on VdoBloom
Aspect ratio is a per-generation control sitting alongside duration and quality. The platform offers Landscape (16:9), Portrait (9:16) and Square (1:1), and a fresh session starts on 16:9 — so switching to Portrait is step one on any Shorts job, not something the model infers from your prompt.
Model support for 9:16 is close to universal but not quite. Veo 3.1 exposes only 16:9 and 9:16, with square filtered out. Seedance 2 Fast accepts 16:9, 4:3, 1:1, 3:4, 9:16 and 21:9. WAN 2.7 Text-to-Video accepts 16:9, 9:16, 1:1, 4:3 and 3:4. The one category to watch is image-to-video: WAN 2.7 Image-to-Video and Reference-to-Video expose no ratio control at all, and the output simply takes the shape of the photo you upload. Crop your source to 9:16 before uploading or you will get a landscape Short.
Duration is the real cost lever
Shorts tolerating up to three minutes does not mean an AI model will hand you three minutes. Most single generations top out between 5 and 15 seconds, so a longer Short is assembled from several clips. That makes cost-per-second, not cost-per-clip, the number to plan around. Credits convert at a flat $0.05 each (Lite is $15 for 300 credits), and these are the real figures.
| Model | Resolution | Duration | Credits | Cost | Cost per second |
|---|---|---|---|---|---|
| Grok Imagine Video 1.5 | 480p | 5s | 8 | $0.40 | $0.08 |
| Grok Imagine Video 1.5 | 480p | 10s | 15 | $0.75 | $0.08 |
| Grok Imagine Video 1.5 | 480p | 15s | 23 | $1.15 | $0.08 |
| Seedance 2 Fast | 480p | 10s | 48 | $2.40 | $0.24 |
| Seedance 2 Fast | 480p | 15s | 72 | $3.60 | $0.24 |
| Seedance 2 Fast | 720p | 15s | 150 | $7.50 | $0.50 |
| WAN 2.7 Text-to-Video | 720p | 15s | 95 | $4.75 | $0.32 |
| WAN 2.7 Text-to-Video | 1080p | 15s | 143 | $7.15 | $0.48 |
| Kling 2.5 Turbo | native | 10s | 80 | $4.00 | $0.40 |
Read that table as a budget plan rather than a quality ranking. A 60-second Short built from four 15-second WAN 2.7 clips at 1080p costs 572 credits, about $28.60. The same 60 seconds drafted on Grok Imagine at 480p costs 92 credits, about $4.60 — low enough to storyboard the whole thing, see whether the sequence works, and only then re-run the shots that survive at a higher tier. Specs for each model live on its own page, for example Seedance 2 Fast and Veo 3.1 Fast.
720p or 1080p for Shorts?
YouTube’s encoder is more forgiving than Instagram’s, and Shorts are frequently watched on cellular with the stream stepped down anyway. 720 × 1280 holds up well for faceless narration, list videos, screen-led explainers and anything where the subject is large in frame. Go to 1080 × 1920 when the shot has fine texture, fast motion or a face filling the frame — those are where compression artefacts become visible.
480p is a drafting tier, not a publishing tier. It is there so you can test whether a prompt produces the motion you asked for before spending real credits.
Composing inside the Shorts interface
Shorts draws its own overlay on your frame: the title and channel handle across the lower-left, the like, comment, remix and share rail down the right edge, and the subscribe button near the bottom. Keep the bottom 15 to 20 percent and the right 12 percent clear of anything load-bearing. The top of the frame is the safest real estate for a hook caption, which is also where the eye lands first.
Prompt for that explicitly. Adding phrases like vertical framing, subject centred in the upper two thirds, generous headroom to your prompt measurably improves composition compared with setting the ratio and hoping. Models default to centre-of-frame compositions built for 16:9 unless you tell them otherwise.
Building a longer Short
For anything past 15 seconds you are stitching. The Creator Reel flow builds a storyboard of clips and bills per clip as it goes, which suits multi-shot vertical stories. The faceless channel flow is built for exactly the narration-over-visuals format that dominates the Shorts shelf. And Clip Studio handles the captioning pass — burned-in captions are close to mandatory on Shorts, where a large share of views start muted.
If you are animating a photograph of a real person for a Short, you must have that person’s consent before you generate.
Before you publish
Free generations carry a watermark; any paid plan downloads clean with commercial rights. New accounts get 10 free credits with no card, which covers a couple of 480p drafts on Grok Imagine so you can sanity-check the vertical framing first. See the pricing page for the current tiers, or start on the free AI video generator. Credit packs start at $2.49 for 75 credits and never expire, which suits bursty Shorts production better than a subscription if you publish in batches.
Frequently asked questions
What resolution should a YouTube Short be?
1080 × 1920 pixels, which is 9:16 vertical. 720 × 1280 is the same ratio at lower cost and is fine for most faceless and talking-head formats.
How long can a Short be?
Up to three minutes. Most AI models generate 5 to 15 seconds per run, so longer Shorts are assembled from multiple clips.
Will a square video still count as a Short?
Yes, square and taller qualifies, but it plays with filler above and below on a phone. Use 9:16.
Does choosing 9:16 change the credit cost?
No. Credits are driven by model, resolution tier and duration. Aspect ratio is free.
Which is the cheapest way to draft a Short?
Grok Imagine Video 1.5 at 480p — 8 credits for 5 seconds, 23 credits for 15 seconds. Draft the sequence there, then re-run the keepers on WAN 2.7 or Seedance 2 Fast.
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