How is video file size calculated?

File size = bitrate (Mbps) x duration (seconds) / 8 (to convert bits to bytes). A 100 Mbps video for 10 minutes: 100 x 600 / 8 = 7,500 MB = 7.3 GB. Audio adds a small additional amount (typically 1.5 Mbps for stereo).

What bitrate does 4K video use?

H.264 4K: 60-150 Mbps. H.265/HEVC 4K: 30-80 Mbps. ProRes 422 4K: 470-700 Mbps. ProRes RAW 4K: 900-1800 Mbps. Canon Cinema RAW: 1-2 Gbps. Higher bitrate = better quality and larger files.

Does frame rate affect file size?

Yes — higher frame rates increase file size proportionally. 60fps produces roughly twice the data of 30fps at the same quality per frame. 120fps (slow motion) produces 4x the data of 30fps. This is reflected in the bitrate setting.

How much storage do I need for a shoot?

For a typical wedding (8 hours of coverage, 2-3 hours of actual recording): at 100 Mbps H.264, expect 90-135 GB. For documentary work at ProRes 422 (500 Mbps), expect 450 GB per hour. Always bring 2-3x the storage you think you need.

PhotoCalcs

Video File Size Calculator — Estimate File Size

Estimate video file size from resolution, bitrate and duration.

Bitrate

Video bitrate

Duration (minutes)

Duration (seconds)

How We Calculate This

File Size Formula

Size (MB) = bitrate (Mbps) x duration (seconds) / 8

Size (GB) = Size (MB) / 1024

The factor of 8 converts megabits to megabytes. This calculates video data only — container overhead and audio add a small additional amount.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.