TikTok Video Resizer
Most footage that ends up on TikTok wasn't originally filmed for TikTok. It came from a DSLR shoot, an Instagram Reel, a YouTube video, a Zoom recording — each with its own native dimensions. This tool resizes whatever you feed it to TikTok's actual spec: 1080×1920 pixels, 9:16.
Resize vs. crop vs. pad — three different operations, often confused
These get used interchangeably in casual conversation, but they do genuinely different things to your footage:
- Resizing scales the entire frame up or down while keeping its full content — a 1920×1080 video resized to fit a 1080-pixel width becomes 1080×607, still showing everything, just smaller.
- Cropping cuts away part of the frame to change its shape — turning that same 1920×1080 clip into 1080×1920 by removing roughly 44% of its width.
- Padding (letterboxing) keeps the full original frame intact and adds black bars to fill out the remaining space to 9:16, rather than cutting anything.
For most repurposed content — landscape footage, square Instagram exports — some combination of resize-then-crop produces the cleanest, most "native-feeling" result. Padding avoids losing any content but visibly signals "this wasn't made for this platform," since a large chunk of the vertical frame ends up solid black.
The target spec, restated plainly
1080×1920 pixels, 9:16 aspect ratio, is TikTok's recommended full-screen format. TikTok's own minimum accepted resolution sits around 540×960 — technically usable, but visibly softer than the 1080×1920 target on modern phone screens, which is why "resize up to the minimum and call it done" is a worse move than resizing properly to the full recommended dimensions.
Repurposing from other platforms specifically
Content originally sized for Instagram Reels or YouTube Shorts is often already close to 9:16 and needs only minor resizing. Content pulled from a landscape source (YouTube long-form, a Zoom recording, camera footage) needs the more significant resize-and-crop treatment described above, and benefits from checking where the main subject sits in frame before the crop is applied — a straight center-resize can still cut off someone standing off to one side.
For the technical standard defining aspect ratio and resolution conversion in video, see the International Telecommunication Union's video recommendations.