Video File Size Calculator
File size from bitrate, duration and audio, plus the bitrate that fits a target size and how your bitrate compares with the recommendation for the resolution.
Video File Size Calculator: with the default inputs, file size is 0.61 GB.
Used for the recommended-bitrate comparison and bits per pixel; the file size comes from your bitrate.
Megabits per second. 1 Mbps = 1,000,000 bits/s, not 1,048,576.
128–192 kbps AAC stereo is normal; 384 kbps for 5.1.
Video plus audio, at a constant bitrate.
- Video track
- 600 MB
- Audio track
- 9.6 MB
- Per minute
- 61 MB
- Per hour
- 3.66 GB
- Total bitrate (Mbps)
- 8.128
- Video bitrate that fits the target (Mbps)
- 13.205
- Recommended video bitrate (Mbps)
- 8
- Bits per pixel
- 0.1286
Assumptions
- Constant bitrate — a CRF or single-pass VBR encode can land well above or below this.
- Bitrates are SI: 1 Mbps = 10⁶ bits/s, 1 GB = 10⁹ bytes.
- Container and metadata overhead (well under 1%) is ignored.
- One video track and one audio track.
- Recommended bitrates are YouTube's H.264 SDR figures, scaled 1.5× above 30 fps.
| Clip length | Size (GB) | Size (GiB) |
|---|---|---|
| 1 minute | 0.061 | 0.057 |
| 10 minutes | 0.61 | 0.568 |
| 30 minutes | 1.829 | 1.703 |
| 1 hour | 3.658 | 3.406 |
| 2 hours | 7.315 | 6.813 |
| 24 hours (continuous recording) | 87.782 | 81.754 |
GB is 10⁹ bytes; GiB is 2³⁰. Drive manufacturers and this calculator use GB, while Windows reports GiB and calls it GB — which is why a '1 TB' drive shows as 931 GB.
How this is worked out
The formula
File size (bytes) = (video bitrate + audio bitrate) × duration ÷ 8 with bitrates in bits per second and duration in seconds. 1 Mbps = 1,000,000 bits/s; 1 byte = 8 bits. Bitrate to fit a target = target bytes × 8 ÷ seconds − audio bitrate Bits per pixel = video bitrate ÷ (width × height × frame rate)
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Resolution
- Used for the recommended-bitrate comparison and bits per pixel; the file size comes from your bitrate.2160p — 4K UHD (3840×2160) · 1440p — QHD (2560×1440) · 1080p — Full HD (1920×1080) · 720p — HD (1280×720) · 480p — SD (854×480) · 360p (640×360)
- Frame rate
- A number.1 or more · defaults to 30
- Video bitrate
- Megabits per second. 1 Mbps = 1,000,000 bits/s, not 1,048,576.0 or more · defaults to 8
- Audio bitrate
- 128–192 kbps AAC stereo is normal; 384 kbps for 5.1.0 or more · defaults to 128
- Duration
- A number.in s, min, h, day · 0 or more · defaults to 10
- Target file size(under More options)
- Used for the 'bitrate to fit' output — e.g. a 25 MB email limit or an 8 GB card.in MB, GB, TB, MiB, GiB · 0 or more · defaults to 1
What you get back
- File sizemain answer
- Video plus audio, at a constant bitrate.
- Video track
- Audio track
- Per minute
- Per hour
- Total bitrate (Mbps)
- Video bitrate that fits the target (Mbps)
- Recommended video bitrate (Mbps)
- Bits per pixel
What this assumes
- Constant bitrate — a CRF or single-pass VBR encode can land well above or below this.
- Bitrates are SI: 1 Mbps = 10⁶ bits/s, 1 GB = 10⁹ bytes.
- Container and metadata overhead (well under 1%) is ignored.
- One video track and one audio track.
- Recommended bitrates are YouTube's H.264 SDR figures, scaled 1.5× above 30 fps.
About this calculator
Video file size is one multiplication: bitrate times duration. Everything else — resolution, codec, frame rate — matters only because it changes the bitrate you need. Enter the bitrate and length and you get the size; enter a size you have to fit and it gives you the bitrate.
Divide by eight
Bitrates are in bits per second and file sizes are in bytes. 8 Mbps for ten minutes is 8,000,000 × 600 = 4.8 billion bits, which is 600 million bytes, or 0.6 GB. Forgetting the ÷ 8 is the single most common error here, and it makes everything eight times too big.
The other trap is GB versus GiB. This calculator uses SI: 1 GB = 10⁹ bytes, the same convention as drive manufacturers, camera specs and network gear. Windows shows GiB (2³⁰ bytes) but labels it "GB", so a file this calculator calls 1.00 GB shows up in Explorer as 0.93 GB. Both are right; only one is honestly labelled.
Constant versus variable bitrate
This is a CBR model: it assumes every second of video gets the same number of bits, which makes the size exactly predictable. Almost nothing is encoded that way any more.
- CBR wastes bits on a static shot and starves a fast pan. Its one advantage is predictability, which is why broadcast and live streaming use it.
- VBR spends bits where the picture needs them. A two-pass VBR encode at an 8 Mbps average lands within a few percent of the CBR prediction, so this calculator is still accurate for planning.
- CRF / constant quality (the default in x264, x265 and most modern encoders) targets a look, not a size. It has no target bitrate at all, and the resulting file can be half or double what you expect depending on how complex the footage is. If you are using CRF, treat this number as a rough upper bound and encode a one-minute sample to calibrate.
Choosing a bitrate
The recommended figure shown is YouTube's published guidance for that resolution, scaled by 1.5× above 30 fps. Two things move the real requirement a long way:
- Codec. H.265/HEVC and AV1 deliver similar quality to H.264 at roughly 50–60% of the bitrate. The recommendations are for H.264.
- Content. Talking heads compress beautifully. Grass, water, snow, confetti, film grain and hard cuts do not. Animation with flat colour is very cheap; a screen recording of scrolling text is not.
Bits per pixel is the resolution-independent way to judge a bitrate — bitrate ÷ (width × height × fps). Around 0.10–0.15 bpp is a solid H.264 delivery encode; below 0.05 you are asking for blocking, and above 0.3 you are mostly wasting storage.
What is not counted
Container overhead (MP4/MKV headers, indexes, timecode) adds well under 1%. Multiple audio tracks, subtitles and chapter data add their own bitrate — add them into the audio field if they matter.
Frequently asked questions
▸How do I calculate video file size?
Multiply the total bitrate in bits per second by the duration in seconds, then divide by 8 for bytes. 8 Mbps for 10 minutes is 8,000,000 × 600 ÷ 8 = 600 MB.
▸How big is an hour of 4K video?
At YouTube's recommended 35–45 Mbps, roughly 16–20 GB an hour. Camera-original 4K at 100 Mbps is about 45 GB an hour, and ProRes is several times that again.
▸What bitrate should I use for 1080p?
8 Mbps at 30 fps and 12 Mbps at 60 fps for H.264 delivery, per YouTube's guidance. H.265 or AV1 reach the same quality at roughly half that.
▸Why is my file smaller than the calculator says?
You are almost certainly encoding with CRF or VBR, which spends bits only where the picture needs them. Easy footage — a static talking head — can come in far under the nominal bitrate.
▸Does frame rate change the file size?
Not directly: size depends on bitrate and duration only. But doubling the frame rate roughly needs 1.5× the bitrate for the same quality, so in practice it does.
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