How is file size calculated?

File size (bytes) = (bitrate in kbps × 1000 ÷ 8) × duration in seconds × codec overhead factor. The overhead factor accounts for container metadata and codec framing; it ranges from ~1.0 for raw streams to ~1.05 for typical MP4/MKV containers.

What bitrate should I enter?

Enter the combined (total) bitrate — video bitrate plus audio bitrate. For example, a 1080p H.264 clip at 8 Mbps video + 192 kbps audio = 8192 kbps total. Check your camera or encoder settings for the exact value.

Why does the codec choice change the file size?

Different codecs and containers have varying amounts of header, index, and metadata overhead. H.264/H.265 in MP4 adds roughly 2–5% overhead over the raw bitrate math. Lossless codecs like ProRes add more because they store much larger frames.

How does the frame-to-timecode conversion work?

Total seconds = frame count ÷ frame rate. The result is then split into hours, minutes, and seconds. For example, frame 1800 at 30 fps = 60.00 s = 0h 1m 0s. Drop-frame timecode (used in 29.97 fps NTSC) is not applied here — this is a simple frame-count conversion.

What frame rates are supported?

Common rates from 23.976 to 120 fps are available in the dropdown, including cinema (23.976, 24), broadcast (25, 29.97, 30), high-frame-rate (48, 50, 59.94, 60), and high-speed (90, 120) presets.

Video Length Calculator

Name: Video Length Calculator
Availability: InStock
Author: Nham Vu

Enter video duration and bitrate to estimate file size, or convert between hours, minutes, seconds, and frames.

Video Parameters

Duration

Hours

Minutes

Seconds

Total Bitrate (video + audio)

kbps

Codec / Container

Enter a duration and bitrate above to estimate file size.

Duration Inputs

Frame Rate (fps)

Timecode (HH : MM : SS)

Hours

Minutes

Seconds

Total Seconds

Total Frames

Duration Summary

Timecode

Total Frames

Total Seconds

Total Minutes

Common Broadcast Slot Comparison

Green bar = current duration fills this much of the slot. Over 100% = exceeds the slot.

Summary

Enter video duration and bitrate to estimate file size, or convert between hours, minutes, seconds, and frames.

How it works

Choose the File Size or Duration Converter tab.
For file size: enter the video duration, total bitrate in kbps, and select a codec to apply its overhead factor.
The estimated file size is displayed in MB and GB with a breakdown by video, audio, and container overhead.
For duration conversion: enter hours, minutes, seconds, or total frames and set the frame rate.
All other fields update instantly — change any one value and the rest recalculate automatically.

Use cases

Estimate storage needs before recording a long event or interview.
Check whether a finished video will fit within an upload size limit.
Convert a frame number from an NLE timeline into a timecode for subtitle sync.
Plan storage for multi-camera shoots with different bitrate profiles.
Confirm a clip duration matches a broadcast slot (e.g. exactly 30 seconds).
Calculate how many minutes of footage fit on a memory card at a given recording bitrate.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu