Short answer: pick Veo 3.1 when a short shot has to look and sound finished — a cinematic 8-second clip in 16:9 or 9:16, delivered up to 4K, with sound generated alongside the picture. Pick Grok Imagine when you need clips longer than 8 seconds in a single pass, formats other than 16:9 and 9:16 (square, 4:3, 3:2 and their portrait versions), or built-in editing and extension of a clip you already have.
Both models make video from a prompt or an image, and both add audio by default. The differences that matter are length, output formats, how you steer the result, and what happens after the first clip.
Veo 3.1 vs Grok Imagine at a glance
The table compares the models as their makers document them. Specs were checked on September 28, 2026, against Google's Gemini API Veo documentation and xAI's developer documentation for Grok Imagine video generation.
| Veo 3.1 (Google DeepMind) | Grok Imagine Video 1.5 (xAI) | |
|---|---|---|
| Clip length per generation | 4, 6 or 8 seconds | 1 to 15 seconds |
| Resolution | 720p, 1080p, 4K | 480p, 720p, 1080p (reference-to-video capped at 720p) |
| Aspect ratios | 16:9, 9:16 | 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3 |
| Frame rate | 24 fps | Not stated in the docs |
| Audio | Always generated with the video | On by default; can be turned off; preset voices (custom audio only for approved partners) |
| Start from an image | Yes, plus first-and-last-frame control | Yes, plus first-and-last-frame and keyframes |
| Reference images | Up to 3 (Veo 3.1 and Veo 3.1 Fast) | Yes (reference-to-video) |
| Extend a clip | +7 seconds per step, up to about 148 seconds total, at 720p | Yes |
| Edit an existing video | Not in the Gemini API | Yes, prompt-based editing of clips up to 8.7 seconds; edited output capped at 720p |
Two notes on reading it. Google describes Veo 3.1's 1080p and 4K options as "state-of-the-art upscaling" in its January 2026 update, so 4K is a delivery format, not a guarantee of more generated detail than 1080p. And neither vendor publishes a comparable speed figure: Google's API lists a range from about 11 seconds to 6 minutes depending on load, and xAI's docs give no end-to-end time.
Clip length: 8 seconds vs up to 15
This is the most practical difference. Veo 3.1 tops out at 8 seconds per generation. Longer sequences come from extension, which adds 7 seconds at a time and drops to 720p, or from cutting several clips together.
Grok Imagine generates up to 15 seconds in one pass. If your idea is one continuous action — a product rotating through a full turn, a character walking the length of a street — that extra time can save you a cut and the risk of a mismatch at the join.
For most social edits, though, 8 seconds is a comfortable shot length. Hooks, reveals and B-roll inserts rarely hold longer than that on screen. If you plan your video as a series of shots rather than one long take, the length gap matters less.
Resolution and formats
Veo 3.1 offers 720p, 1080p and 4K. Grok Imagine's ceiling is 1080p, and its default is 480p for faster output. If the clip is going on a large screen, or into a 4K edit timeline, Veo 3.1 is the safer choice.
Grok Imagine wins on shape. Seven aspect ratios cover square feed posts, taller portrait crops (3:4 and 2:3) and classic 4:3 without reframing afterwards. Veo 3.1 generates only 16:9 and 9:16, which covers YouTube, Shorts, Reels and TikTok but means cropping for square or 4:3 placements.
Audio and dialogue
Both models create the soundtrack with the picture instead of leaving you to add it later. Google says Veo 3.1 generates "sound effects, ambient noise, and even dialogue" natively, and audio is always on. Grok Imagine includes an audio track by default, lets you request a silent video, and accepts up to three preset voices per request.
In practice, write sound into the prompt for either model: name the ambience, the key effect and any spoken line in quotes. Keep dialogue short: an 8-second clip fits a line or two, not a conversation.
Steering the result: references, frames and editing
Veo 3.1 gives you three ways to control a shot beyond the prompt:
- Image to video — start from a still so the look, framing and subject are fixed from the first frame.
- First and last frame — add an end image and the model builds the move between the two.
- Reference images — up to three images of a character, product or setting to keep them consistent across separate clips.
Grok Imagine covers similar ground — image to video, first-and-last-frame pinning, keyframes and reference images — and adds one thing Veo 3.1's API does not: prompt-based editing of an existing clip. If your workflow is "generate, then keep adjusting the same clip," Grok Imagine's editing is the stronger fit. If it is "lock the look with a still, then generate variations," both work, and Veo 3.1's higher resolution ceiling becomes the tiebreaker.
Which should you use?
Choose Veo 3.1 if:
- The clip is a hero shot, ad insert or trailer beat that must look polished at 1080p or 4K.
- You deliver in 16:9 or 9:16 and plan the video as a series of short shots.
- You want to fix the opening (and optionally the closing) frame from your own images.
Choose Grok Imagine if:
- You need a single continuous shot longer than 8 seconds.
- You publish in square, 4:3 or 3:2 formats and don't want to crop.
- You want to edit or extend a clip in place rather than regenerate it.
Many teams use more than one model: one for the shots that carry the video and another for longer takes or odd formats. The useful habit is to test your actual brief on each rather than rely on anyone's general ranking.
Trying Veo 3.1 here
Veo Video runs three Veo 3.1 tiers — Veo 3.1, Veo 3.1 Fast and Veo 3.1 Lite. Every generation is an 8-second clip with sound, in 16:9 or 9:16, at 720p, 1080p or 4K. You can start from text or from an image, with an optional end frame; Veo 3.1 Fast also accepts up to three reference images. Clip extension and 4- or 6-second lengths are not available here. Grok Imagine is not offered on this site.
A sensible first test is one shot from your real project on Veo 3.1 Lite at 720p — new accounts get 30 credits, which covers exactly one such clip. Move to Veo 3.1 when you need the highest fidelity. If a scene needs one continuous take longer than 8 seconds, the AI video generator also runs MiniMax H3 Max for longer single clips.
For how Veo 3.1 compares with other models, see Veo 3.1 vs Kling AI and Veo 3.1 vs Sora 2.