Aspect ratio calculator
Enter your video's width and height; the calculator returns the simplified ratio and the exact centered crop your footage yields for each platform format — 9:16 for TikTok, Reels and Shorts, 1:1 and 4:5 for feeds, 16:9 for YouTube. Free, in your browser, no signup.
16:9 (1.7778)
| target | export | crop from your frame |
|---|---|---|
| 9:16 (Reels / TikTok / Shorts) | 1080×1920 | 1215×2160 centered |
| 1:1 (feed square) | 1080×1080 | 2160×2160 centered |
| 4:5 (IG portrait) | 1080×1350 | 1728×2160 centered |
| 16:9 (YouTube) | 1920×1080 | 3840×2160 centered |
Why aspect ratio decides more than shape
Every reformat is a negotiation between what you shot and what the platform displays full-screen. The calculator makes the negotiation explicit: it shows exactly how much frame each target keeps, which is the honest input to decisions like camera placement and where your face can safely sit. Never runs this same math automatically for every deliverable — this page is the manual version, free because it costs nothing to give away.
Read the transcript
Aspect ratio calculator Enter your video's width and height; the calculator returns the simplified ratio and the exact centered crop your footage yields for each platform format — 9:16 for TikTok, Reels and Shorts, 1:1 and 4:5 for feeds, 16:9 for YouTube. Free, in your browser, no signup.
Frequently asked questions
What does 'crop from your frame' mean in the results?
The largest window of your source that matches the target ratio. A 3840×2160 source contains a 1215×2160 window at 9:16 — that window scales to 1080×1920 cleanly. Anything outside it is what a vertical crop gives up.
Why does 4K matter for vertical clips?
A 9:16 crop keeps about a third of a 16:9 frame's width. From 4K that third is still sharper than 1080p output needs; from a 1080p source it must upscale. If vertical clips are a primary output, record in 4K.
Which ratio should I export for each platform?
9:16 (1080×1920) for TikTok, Reels and Shorts; 16:9 (1920×1080) for YouTube long-form; 1:1 or 4:5 for square-leaning feeds. The deeper answer — composing for the platform's UI overlay — is what the safe-zone checker shows.