Video Bitrate & File-Size Calculator

The AT USE Video Bitrate & File-Size Calculator solves the three-way relationship between video bitrate, file size, and duration. Enter any two values and the third is computed instantly in your browser. A video editor knows the target output file must stay under 25 MB for an email attachment and that the clip runs 4 minutes 30 seconds — the calculator returns the maximum combined bitrate available for that constraint. A conference organizer knows sessions will be recorded at 8 Mbps and run 45 minutes each — the calculator shows each session file will occupy approximately 2.7 GB. All computation runs client-side; no data is sent anywhere.

The bitrate formula and why container overhead matters

The theoretical file size of a video is: (video bitrate + audio bitrate) × duration in seconds ÷ 8 = size in bytes. A 10-minute video at 8 Mbps video + 192 kbps audio works out to 594 MB in raw stream data. In practice, the container format (MP4, MKV, MOV) adds a header, a moov atom, and index structures that increase the actual file size by roughly 1–3%. The calculator includes a configurable overhead field — default 1% — so your estimate accounts for the container rather than treating the file as a pure bitstream. When storage cost or upload limits are precise constraints, that 1–3% matters.

Audio bitrate configuration

The audio stream is budgeted separately from the video stream. Common delivery configurations: 192 kbps AAC stereo for YouTube and standard web delivery; 128 kbps AAC for compressed social exports; 320 kbps for music video masters; 48 kbps for voice-only conference recordings where bandwidth is the constraint. The calculator accepts any value in kbps, not just round-number presets. For productions with multiple audio tracks — a main stereo mix, a director commentary track, and subtitles — add each track's bitrate individually and the total budget updates in real time.

YouTube preset bitrates

YouTube's recommended upload bitrates for SDR content: 1080p 30fps = 8 Mbps; 1080p 60fps = 12 Mbps; 1440p 30fps = 16 Mbps; 1440p 60fps = 24 Mbps; 4K 30fps = 35–45 Mbps; 4K 60fps = 53–68 Mbps. The preset chips in the calculator populate these values in one click, so you can immediately verify what a 4K 60fps upload at YouTube's recommended bitrate will weigh at any duration. For HDR content, YouTube's recommended bitrates are higher — 12 Mbps for 1080p60 HDR, 66 Mbps for 4K 60fps HDR — and those are also available as preset chips.

Comparing H.264 and H.265 budgets

H.265 (HEVC) achieves equivalent visual quality to H.264 at approximately half the bitrate. A streaming master that requires 8 Mbps in H.264 typically needs only 4–5 Mbps in H.265 to look the same to a viewer. The calculator does not encode video, but you can compare both scenarios side-by-side: enter the same duration and quality target at 8 Mbps, then re-enter at 4 Mbps — the file size delta shows the storage savings of switching codecs, which informs whether re-encoding an existing library is economically worthwhile at a given storage cost per GB.