There is no single correct image size for every AI video tool. Supported dimensions, aspect ratios, upload limits, and internal resizing can change by product and model version. The safe rule is to check the current interface or official documentation, match the intended destination ratio, and start from the best real source that meets or exceeds the useful input size.
More pixels are not automatically better if they come from repeated enlargement or if the frame is poorly composed. Subject clarity and motion space matter alongside dimensions.
Start with the current tool requirement
Record accepted formats, maximum upload size, supported ratios, and any automatic crop shown by the current product. Do not copy a number from a different model or an old tutorial. If the interface transforms the image before generation, save a screenshot or note of the displayed crop for the test record.
Use an appropriate format: a high-quality JPEG can suit an opaque photograph, while PNG is useful for lossless graphics or alpha when the product supports it. Avoid unnecessary conversions before upload.
Prefer real source detail over synthetic pixel count
Inspect pixel dimensions and the size of the important subject inside the frame. A large canvas with a tiny face may provide less usable identity detail than a smaller, well-framed portrait. Use the original capture or master export rather than a thumbnail enlarged several times.
An AI upscale may create a cleaner input in some workflows, but it also introduces estimated detail. Compare a direct and an enhanced input if exact identity, text, or product features matter, and retain both sources.
Match ratio and leave motion space
Prepare the starting image in the destination shape—landscape, square, or vertical—when possible. Leave margin in the direction of intended movement and keep protected details away from likely interface overlays. A tightly cropped source makes the model invent content as soon as the subject or camera moves.
Create separate compositions for materially different ratios. Cropping a finished landscape generation into a vertical clip can discard the very motion the model produced.
Input-image checklist
Confirm current product support; use a sharp authorized source; match destination ratio; check subject size, text, and edges; remove distracting artifacts; leave motion space; and save the untouched original. Generate a short candidate before spending time on a full sequence.
Evaluate the native result for crop, identity, texture, flicker, and compatibility. The accepted input is the one that produces the required shot reliably—not simply the file with the largest dimensions.
Conclusion
Choose image size from the live tool requirement and final frame, then prioritize real subject detail and usable motion space. Follow image-to-video preparation and learn why AI video crops subjects.
Editorial note: This answer was drafted with AI assistance, then checked and edited against the sources listed below on September 13, 2026. It does not report an unperformed product test.
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