How to Use the MP4 Bitrate Calculator
Enter your target file size in MB, the video duration, and the audio bitrate. The calculator returns the required video bitrate in kbps and Mbps, which you can use directly in Handbrake, FFmpeg, Adobe Premiere, or DaVinci Resolve.
The Bitrate Formula
Total bitrate (kbps) = file size (MB) × 8 × 1024 ÷ duration (sec). Video bitrate = total bitrate − audio bitrate. For example, a 500 MB video at 5 min 30 sec with 128 kbps audio needs a video bitrate of about 12,019 kbps.
Recommended Bitrates by Resolution (H.264)
- 480p — 500–1,000 kbps
- 720p — 1,500–4,000 kbps
- 1080p — 4,000–8,000 kbps
- 4K — 10,000–20,000 kbps
Frequently Asked Questions
Does H.265 need a lower bitrate than H.264?
Yes — H.265 achieves the same quality at roughly half the bitrate. A 1080p video needs only 2,000–4,000 kbps with H.265 vs 4,000–8,000 kbps with H.264.
Email attachment limit is 25 MB — what bitrate do I need for a 5-min video?
25 MB × 8 × 1024 ÷ 300 sec = 683 kbps total. Subtract 128 kbps audio = about 555 kbps video bitrate. That's around 480p quality.