How Big Is a Video? File Size per Minute at 4K, 1080p and 720p

Video size is bitrate times time. A bitrate in megabits per second (Mbps) times 60 seconds, divided by 8 bits per byte, gives megabytes per minute. That is the same as multiplying by 7.5.

MB per minute = Mbps x 60 / 8 = Mbps x 7.5
GB per hour   = Mbps x 0.45

Add audio if you care: a 128 kbps audio track adds about 1 MB per minute. Get the real bitrate of your file from QuickTime Player (Window > Show Movie Inspector, or Command-I), which lists the data rate.

This table converts the bitrates YouTube recommends for SDR uploads into file size. These are delivery bitrates, a reasonable target for a finished video, not what a camera records. The conversion is our arithmetic.

Per hour, multiply by 60: a 1080p30 video at 8 Mbps is about 3.6 GB an hour. These figures assume H.264. A newer codec like H.265 reaches similar quality at a lower bitrate, so the same video can be smaller. See H.265 vs H.264.

4K has four times the pixels, but the file is not always four times larger. We re-encoded one 4-second synthetic 4K60 clip at the same quality setting (H.264, CRF 23, ffmpeg 8.1.1, Apple M2 Pro, 8 November 2026):

At a fixed quality, 4K cost 7.2 times a 1080p file, more than the pixel ratio, because an encoder spends more bits per frame on finer detail. YouTube’s recommended bitrates give a smaller gap, about 4.4 to 5.6 times for 30 fps. The clip is synthetic, so use the ratios as direction, not as a promise for your footage.

Multiply the per-minute figure by 60, or use the shortcut of 0.45 GB per Mbps. Same YouTube bitrates, 30 fps, our arithmetic:

The 4K row uses the middle of YouTube’s 35 to 45 Mbps range. Use this to plan a drive for a shoot or to guess whether a recording will fit an upload limit. For limits at the receiving end, see compressing video for email.

A lot, and it works independently of resolution. We encoded the same 1080p30 clip with H.264 at three CRF values (lower CRF means higher quality; same machine and date):

Each 5-step move roughly doubled or halved the file. That is why two 1080p videos of the same length can differ five-fold in size. Resolution sets the baseline, the quality setting sets the multiplier, and the codec shifts the whole curve. Our compress video on Mac guide shows how to pick a value.

Because cameras record for editing, not for sharing. They use higher bitrates and sometimes heavy codecs. Apple says ProRes files are up to 30 times larger than HEVC files. Compare your Movie Inspector bitrate to the table: if it is well above, you have room to shrink the file. See why a video file is so large and why iPhone videos are so large.

To cut a file to the table’s size, re-encode it. The guide to reducing video file size on Mac covers the options.

To size a video, you need only arithmetic and QuickTime Player. To shrink one clip, QuickTime Player’s File > Export As or the avconvert command is free and enough.

Smol helps when you have many clips or want exact control. It compresses video to MP4, MOV, WebM or MKV with H.265 by default, a quality label or exact CRF 0 to 63, and an optional lower resolution. Drop a whole folder in or use the Finder right-click action. Nothing is uploaded. It costs $29 once for one Mac. Compare tools in the best video compressor for Mac.