ShrinkIt
Every video compressor asks you the same question in different clothes: how much quality do you want to keep? Resolution is the biggest lever you have. Pick too high and the file barely shrinks; pick too low and faces turn to mush. This guide explains what those numbers — 1080p, 720p, 480p, 360p, 144p — actually mean, what they do to file size, and how to choose without second-guessing yourself.
What the numbers mean
The "p" figure is the video's height in pixels (the p itself stands for progressive scan). A 1080p video is 1,920 × 1,080 pixels in a standard 16:9 frame; 720p is 1,280 × 720; 480p is 854 × 480, and so on down to 144p, a thumbnail-sized 256 × 144. What matters for file size is the total pixel count, and it falls faster than the height number suggests:
| Resolution | Pixels per frame (16:9) | Relative to 1080p |
|---|---|---|
| 1080p | ~2.07 million | 100% |
| 720p | ~0.92 million | ~44% |
| 480p | ~0.41 million | ~20% |
| 360p | ~0.23 million | ~11% |
| 144p | ~0.04 million | ~2% |
Halving the height roughly quarters the pixels. That is why stepping from 1080p to 720p — a change many viewers won't notice on a phone — can already make a large dent in file size, and why 480p files are so much smaller again.
Resolution isn't the whole story: bitrate
Two videos at the same resolution can differ wildly in size, because compressors also control bitrate — how many bits are spent per second of footage. Resolution sets how many pixels there are; bitrate sets how faithfully they're reproduced. A sensible compressor lowers both together: fewer pixels need fewer bits to look clean. This is also why content matters. A static shot of someone talking compresses beautifully; a shaky handheld clip of confetti falling at a concert fights the encoder on every frame. If your compressed video looks blocky, the content probably needed more bits than the setting allowed — step up one level.
Match the preset to the destination
1080p — keepers and big screens
Use minimal compression when the video will be watched on a TV or a large monitor, or when it's a memory you want to archive at high quality. You still save space versus the camera original — camera footage is encoded generously — but quality stays essentially indistinguishable.
720p — the everyday default
On a phone held at arm's length, 720p is very hard to tell from 1080p. It's the classic balance of quality and size: good enough to share proudly, small enough to send and store without thinking about it. When in doubt, start here.
480p — casual sharing
Standard-definition territory. Ideal for clips whose job is communication rather than cinematography: the dog doing the thing, the parking spot you're in, a quick how-to for a colleague. Noticeably softer on close inspection, perfectly watchable in a chat bubble.
360p — built for messaging
Messaging apps often re-compress what you send anyway, and chat videos are watched small. 360p gets files down to sizes that send fast even on weak connections, which is frequently the difference between "sent" and "spinning."
144p — maximum shrink
The nuclear option: maximum compression for minimal storage. Detail is largely gone, but the video remains identifiable — useful when you need a reference copy of long footage, or when storage pressure beats every other concern.
When a preset is the wrong tool
Presets answer "how good should it look?" Sometimes the real question is "how big can it be?" — a 25 MB email cap, an upload limit, a form that rejects anything over 50 MB. In those cases, work backwards from the number instead: set a target file size and let the compressor choose settings to land near it. We cover the email case in detail in how to compress a video for email.
How ShrinkIt helps
ShrinkIt ships exactly these five presets — 1080p Full HD, 720p HD, 480p SD, 360p, and 144p — plus a custom target size in MB for hard limits, with up to 90% size reduction at the lowest setting. It shows original size, compressed size, and space saved in real time for each video, so you can see precisely what a preset costs and buys. Compression is hardware-accelerated on your iPhone with Apple's AVFoundation, keeps the original aspect ratio, and never uploads anything: no account, no internet required. You can also set a default preset so your usual choice is one tap away.
Practical rules of thumb
- Archiving a memory? 1080p. Storage is cheaper than regret.
- Sharing to a person or group chat? 720p for things you're proud of, 360p–480p for things that just need to be seen.
- Fighting a size limit? Skip presets; use a target size.
- Freeing up storage in bulk? 480p–720p for most phone footage; see our storage guide for a full workflow.
- Not sure? Compress a copy, compare, and keep whichever you're happy with. A compressor that preserves your original (deleting it only if you opt in) makes this experiment free.
Resolution choice sounds technical, but it reduces to one question: where will this video be watched? Match the pixels to the screen and the occasion, and you'll stop paying storage and bandwidth for quality nobody ever sees.