🔒 100% Client-Side · No Video Uploaded

A video bitrate calculator works backward from your target file size limit to determine the maximum video and audio bitrates. Enter the file size cap (Discord free 10MB, Discord Nitro 500MB, X/Twitter 512MB), video duration, resolution, and codec to get exact encoder settings for Premiere Pro or DaVinci Resolve. Sizes here are decimal: 1 MB is 1,000,000 bytes.

Export Parameters

File Size Target
Video Duration
Resolution & Audio
Codec & Frame Rate
Container & Bitrate Mode

Export Settings

Target Video Bitrate —
Total Bitrate —
Audio Allocation —
Predicted File Size —
Video : Audio Split —
Bits Per Pixel —
Codec Efficiency —

Quality Assessment

Unwatchable Low Acceptable Good Excellent

Enter your parameters to see the quality forecast.

File Size Breakdown

Video Audio Overhead (1% reserved)

Export Commands

ffmpeg -i input.mp4 -c:v libx264 -b:v ____k -c:a aac -b:a 128k output.mp4
Configure your export settings as shown above.
Configure your Deliver page settings as shown above.
handbrake-cli -i input.mp4 -o output.mp4 -e x264 -b ____ -B 128

Resolution Comparison

Same file size limit at different resolutions

Resolution Video Bitrate BPP Quality
Enter parameters to see the comparison.

How It Works

Set Your Limit

Enter the maximum file size your platform allows — Discord, X/Twitter, email, or any custom cap.

Add Duration

Specify how long your video is in minutes and seconds. Choose your codec and frame rate.

Get Bitrate

We calculate the exact bitrate to fit your file under the limit and assess the resulting quality.

Copy & Export

Get copy-paste FFmpeg commands, Premiere Pro settings, DaVinci Resolve config, and Handbrake CLI.

Video Editing Efficiency Gear

If you are frequently exporting videos and battling file size limits, your export render times are likely slowing you down. We strongly recommend editing on a high-speed NVMe SSD to eliminate timeline lag and drastically speed up your encoding. For dialing in complex export settings without clicking through endless menus, map your custom export presets to a macro editing console to streamline your workflow.

How to Calculate Video Bitrate from File Size

When you are trying to share a video on Discord (10MB on a free account, 500MB with Nitro) or X/Twitter (512MB limit), you can't just guess your export settings. If you export at too high a bitrate, the file will be too large and the platform will reject it. If you export too low, the video will look like a pixelated mess. Bitrate is quoted in bits per second and file size in bytes, so the eight between them is not optional: File Size (bytes) = Total Bitrate (bits per second) × Duration (seconds) ÷ 8. BitrateBoss reverses that equation. You input the strict file size limit and the exact duration of your video, and we calculate the maximum allowable video and audio bitrate. We reserve 1% of the budget for container overhead, round the video bitrate down rather than up, and provide copy-paste FFmpeg commands, so the finished file lands under the limit rather than just beside it.

One convention decides whether the file fits: this calculator reads MB and GB as the decimal sizes their labels mean, so 1 MB is 1,000,000 bytes and 1 GB is 1,000,000,000 bytes. Your operating system usually reports the binary sizes under the same two labels (1 MiB is 1,048,576 bytes, 4.9% larger; 1 GiB is 1,073,741,824 bytes, 7.4% larger). Sizing against the decimal reading is the safe direction, because a file that fits a decimal cap also fits a binary one, and never the reverse.

Frequently Asked Questions

How do you calculate video bitrate from a file size limit?

Bitrate = (Target File Size in bits - Audio Bitrate × Duration) / Duration, with 1% of the budget held back for container overhead. For a 10MB Discord free-tier cap with a 60-second video and 128kbps audio: (10 × 8,000,000 × 0.99 - 128,000 × 60) / 60 = 1,192 kbps video bitrate. This is the maximum video bitrate that will keep the finished file under the limit.

What bitrate is good enough for 1080p video?

YouTube recommends 8,000 kbps for 1080p at 30fps and 12,000 kbps at 60fps. Below 5,000 kbps, compression artifacts become visible in high-motion scenes. Below 2,500 kbps, quality degrades noticeably in all content. For screen recordings with little motion, 3,000-4,000 kbps at 1080p looks acceptable.

What is the difference between CBR and VBR encoding?

Constant Bit Rate (CBR) maintains the same bitrate throughout the video — predictable file sizes but wastes bits on static scenes. Variable Bit Rate (VBR) allocates more bits to complex scenes and fewer to simple ones — better quality per byte but less predictable file sizes. Use CBR for streaming and VBR for file uploads.

Does MB mean 1,000,000 bytes or 1,048,576 bytes here?

1,000,000. BitrateBoss reads MB and GB as the decimal sizes their labels mean, so 1 MB is 1,000,000 bytes and 1 GB is 1,000,000,000 bytes, which is how drive and disc capacities are published. Your operating system usually reports binary sizes under the same two labels (1 MiB is 1,048,576 bytes, 4.9% larger; 1 GiB is 1,073,741,824 bytes, 7.4% larger). Decimal is the safe direction: a file sized to fit a decimal cap also fits a binary one, but a file sized to a binary cap overshoots a decimal cap by 4.9%.