File Size Estimator

Video file size is determined by two variables: bitrate (in megabits per second) and duration. Multiply them together and divide by 8 to convert bits to bytes. A 1-hour video at 50 Mbps requires 22.5 GB of storage — before any audio tracks, metadata, or container overhead.

The formula

File size in bytes = duration_seconds × bitrate_bits_per_second / 8

In practical units (duration in minutes, bitrate in Mbps):
  bytes    = duration_min × 60 × bitrate_Mbps × 1,000,000 / 8
  megabytes = bytes / 1,000,000
  gigabytes = bytes / 1,000,000,000

Example: 60 minutes at 50 Mbps
  bytes = 60 × 60 × 50,000,000 / 8 = 22,500,000,000 bytes
  GB    = 22,500,000,000 / 1,000,000,000 = 22.5 GB

Sizes are in SI gigabytes (1 GB = 1,000,000,000 bytes), consistent with how camera storage displays, video software, and drive manufacturers report capacity.

Practical examples

Example 1 — 4K interview capture, 1 hour. ProRes HQ at 4K: ~1880 Mbps. 60 × 60 × 1,880,000,000 / 8 = 846 GB per hour. A 2 TB SSD holds about 2.4 hours of footage.

Example 2 — YouTube 1080p at 30 fps. YouTube's recommended bitrate for 1080p 30fps H.264 is 8 Mbps. A 10-minute video: 10 × 60 × 8,000,000 / 8 = 600 MB.

Example 3 — DSLR video recording limit. Many DSLRs record H.264 at ~40–50 Mbps. At 50 Mbps, a 32 GB card holds: 32,000 MB × 8 / 50 / 60 ≈ 85 minutes of footage.

Common mistakes

• Forgetting that 1 Mbps = megabits, not megabytes. The formula divides by 8 to convert. If you enter a bitrate in MB/s instead of Mbps, multiply by 8 first.
• Not accounting for audio. This calculator estimates video track size only. A stereo AAC audio track at 256 kbps adds about 112 MB per hour — under 1% of most high-bitrate video files, but significant for heavily compressed web video.
• Using binary GB instead of SI GB. Cameras and video software display remaining time in SI GB. This calculator uses SI consistently. If your storage device shows capacity in GiB (Windows), divide by 1.074 to convert.
• Confusing CBR (constant bitrate) with VBR (variable bitrate). This formula assumes CBR. Most modern codecs use VBR, so actual file size varies. The result is an estimate based on the average bitrate.

Common video bitrate reference