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Bitrate Calculator

Work backwards from a file size limit to the bitrate that will hit it. Enter the target size, the length of the recording and the audio bitrate; the calculator returns the total bitrate and the video bitrate to give your encoder.

Quick examples
kbps

Subtracted from the total to leave the video bitrate. Use 0 for no audio.

Your numbers stay in your browser. Nothing is uploaded.
Video bitrate909 kbps
Total bitrate
1,037 kbps
Total bitrate in Mbps
1.037 Mbps
File size per minute
7.78 MB

Saved setups

Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.

    Your recent calculations

    Results you calculate here are kept on this device so you can come back to them.

      Formula

      Total bitrate (kbps) = file size in bytes × 8 ÷ duration in seconds ÷ 1,000
      Video bitrate = total bitrate − audio bitrate
      1 Mbps = 1,000 kbps

      How to use it

      1. Enter the file size you need to stay under.
      2. Enter the duration.
      3. Enter the audio bitrate you will use, or 0 for silent video.
      4. Set your encoder’s video bitrate slightly below the result to leave room for container overhead.

      Worked examples

      A 90-minute video in 700 MB with 128 kbps audio: 5,600,000,000 bits ÷ 5,400 s

      Total bitrate
      1,037 kbps
      Video bitrate
      909 kbps
      Total bitrate in Mbps
      1.037 Mbps

      A 2-hour film in 4 GB with no audio track

      Total bitrate
      4,444 kbps
      Video bitrate
      4,444 kbps
      Total bitrate in Mbps
      4.444 Mbps

      A 30-second clip in 10 MB with 96 kbps audio

      Total bitrate
      2,667 kbps
      Video bitrate
      2,571 kbps

      Hitting the size accurately

      A bitrate target only lands on the size when the encoder actually averages that rate. Use two-pass or average-bitrate (ABR) mode rather than a quality-based mode such as CRF, and aim 2–3% under to cover the container’s own overhead.

      Is the bitrate enough?

      As a reference, YouTube’s recommended upload bitrates for standard frame-rate SDR video are about 5 Mbps for 720p, 8 Mbps for 1080p, 16 Mbps for 1440p and 35–45 Mbps for 4K. If your result is far below the figure for your resolution, lower the resolution or raise the size limit.

      Questions people ask

      What bitrate fits a 90-minute video into 700 MB?

      About 1,037 kbps in total. With 128 kbps audio that leaves 909 kbps for video.

      How do I convert kbps to MB per minute?

      Multiply kbps by 60, divide by 8, then divide by 1,000. 1,000 kbps is 7.5 MB a minute.

      Does resolution affect file size?

      Not directly. Size is bitrate × duration. Resolution only changes how good the picture looks at that bitrate.

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