Which video quality should you download?
Highest is not always right. Resolution decides file size far more than it decides how good the video looks on your screen.
Resolution is not quality
A 4K file is not automatically sharper than a 1080p one. What you see depends on the bitrate the source was encoded at, on how the video was shot, and above all on the screen you watch it on.
On a phone, the difference between 1080p and 4K is essentially invisible: the panel cannot resolve it and your eye is too close to the wrong pixels. On a large television, it is obvious.
What each step costs
For ten minutes of video, expect roughly 100 MB at 720p, 200 MB at 1080p, and 700 MB or more at 4K. The jump from 1080p to 4K quadruples the pixel count and, in practice, triples to quadruples the size.
That is the whole trade-off. A two-hour film at 4K is comfortably over eight gigabytes; the same film at 1080p fits in two.
Picking by screen
Phone or tablet: 720p is genuinely enough, and 1080p is generous.
Laptop or standard monitor: 1080p. Most laptop panels cannot display more anyway.
Television above fifty inches, or any screen you sit close to: 4K if the source offers it, otherwise 1080p.
Archiving, or footage you plan to edit and crop: take the highest available. Cropping consumes resolution, so the headroom is used rather than wasted.
MP4, MKV or WEBM
MP4 is the safe answer. It plays on every phone, television, console and editing suite, and it is what you should pick unless you have a reason not to.
MKV holds more: several audio tracks, subtitles, chapters. It is the right container for films you keep, and it is refused by a good share of televisions and older players.
WEBM is web-native and efficient, and remains poorly supported outside browsers. Choose it if the file is destined for a website.
Why the file is bigger than you expected
Frame rate doubles the cost: a 60 fps video carries twice the frames of a 30 fps one, for the same duration and resolution.
Content matters too. A static talking head compresses extremely well; a handheld shot of foliage in the wind defeats the encoder and inflates the file, at any resolution.
Frequently asked questions
Is 4K worth downloading?
On a large television or for footage you intend to edit and crop, yes. On a phone or a standard laptop screen, you are spending three to four times the disk space for a difference you cannot see.
How big is a 4K video?
Roughly 700 MB for ten minutes, against about 200 MB at 1080p. A feature film at 4K comfortably exceeds eight gigabytes.
Should I choose MP4 or MKV?
MP4 unless you need several audio tracks, subtitles or chapters — that is what MKV is for. MP4 plays essentially everywhere; MKV is refused by many televisions.
Why is my download larger than the original video?
Usually frame rate or content. A 60 fps video carries twice the frames, and footage full of movement and fine detail compresses far worse than a static shot.