How is video file size calculated?

File size = (video bitrate + audio bitrate) × duration in seconds ÷ 8. Bitrate is in bits per second; dividing by 8 converts to bytes. The tool adds a typical 192 kbps AAC audio track by default.

Why does my actual file differ from the estimate?

Variable bitrate (VBR) encoders adjust bitrate based on scene complexity. Simple static scenes compress more; fast action or noise compresses less. The estimate assumes a constant bitrate (CBR), so treat it as a planning guide, not an exact figure.

What bitrate should I use for 1080p?

YouTube recommends 8 Mbps for 1080p30 H.264 and 5 Mbps for H.265. Broadcast-quality 1080p is typically 15–50 Mbps. For web delivery, 4–8 Mbps is a common range.

Does resolution affect file size directly?

Resolution determines how many pixels must be encoded per frame, which influences the bitrate needed for good quality — but the file size formula uses bitrate and duration, not resolution directly. Higher resolution typically requires a higher bitrate to look good.

Is audio included in the estimate?

Yes. The tool adds a 192 kbps stereo AAC audio track by default. You can set it to 0 if your video has no audio or a different rate.

Video File Size Calculator

Enter your video resolution, frame rate, bitrate, and duration to instantly estimate the file size in MB and GB.

Video Parameters

Resolution

Frame Rate (fps)

Video Bitrate

Audio Bitrate (kbps)

Duration

Hours

Minutes

Seconds

Estimated File Size

Fill in the parameters and click Calculate.

Common Bitrate Presets

Resolution	H.264	H.265
240p	0.5 Mbps	0.3 Mbps
480p	2.5 Mbps	1.5 Mbps
720p 30fps	5 Mbps	2.5 Mbps
1080p 30fps	8 Mbps	4 Mbps
1080p 60fps	12 Mbps	6 Mbps
4K 30fps	35–45 Mbps	15–20 Mbps
4K 60fps	50–68 Mbps	25–35 Mbps

Summary

This calculator estimates how large a video file will be based on its bitrate and duration, with an optional audio track included. Simply enter the bitrate (Mbps or Kbps) and the length of your video to get an instant size estimate in both MB and GB. All calculations run entirely in your browser — no file upload required.

How it works

Select your video resolution or enter a custom width and height.
Choose the frame rate (fps) of your video.
Enter the video bitrate in Mbps or Kbps.
Set the video duration in hours, minutes, and seconds.
The estimated file size appears instantly in both MB and GB.
Adjust any value to recalculate on the fly.

Use cases

Planning disk space before recording a long video session.
Estimating upload size for YouTube, Vimeo, or social media.
Checking whether a video fits on a USB drive or SD card.
Comparing storage needs across different resolutions and codecs.
Budgeting cloud storage for video archives.
Verifying export settings in video editors like Premiere or DaVinci Resolve.

Frequently Asked Questions

Last updated: 2026-06-13 · Reviewed by Nham Vu