Is this estimate exact?

No. It is a practical approximation based on average bitrate and duration. Real files will differ slightly due to container overhead, headers, timecode, subtitles, and how your encoder implements variable bitrate.

Should I use Mbps or Kbps for video?

Most modern video workflows quote bitrates in Mbps, especially for HD and 4K content. Use Kbps when working with audio-only streams or very low-resolution video where bitrates are in hundreds of kilobits per second.

How do I include audio bitrate in the estimate?

Add the average audio bitrate to the average video bitrate before you enter the number if you want the file-size estimate to reflect the full media package. For example, an 8 Mbps video plus 128 Kbps audio is about 8.128 Mbps total.

Why is the actual export sometimes larger or smaller than the estimate?

Most encoders use variable bitrate, container overhead varies, and extra tracks or metadata add data beyond the core video stream. Treat the output as a planning estimate, not a guaranteed final byte count.

Can I use this for streaming bandwidth planning?

Yes, as a directional guide. Multiply the estimated file size by expected views or use bitrate directly with viewer hours to budget total data transfer, then compare against CDN or cloud egress pricing.

Why does my OS show a slightly different size?

Operating systems sometimes report sizes in binary units (MiB/GiB: 1,048,576 bytes per MiB) instead of decimal MB/GB. This, plus metadata overhead, explains small differences between the estimate and what you see on disk.

Does this handle multiple audio tracks and subtitles?

Indirectly. You can increase the bitrate input slightly or add rough estimates for extra tracks to approximate their impact, but the calculator does not model each track separately.

Can this tell me the bitrate I need to hit a target file size?

Not directly. This route solves the forward problem: bitrate plus duration to file size. If you need the inverse, rearrange the same formula or use a dedicated target-bitrate calculator.

tech calculator

Video File Size Calculator

Estimate video or audio file size from bitrate and duration before you export, upload, or archive the file.

Results

File size (MB): 375.00
File size (GB): 0.38

Overview

The planning question creators usually ask is not just `what bitrate should I use?` It is `how big will this export be?` If you already know the average bitrate and runtime, you can estimate file size before you hit render and avoid trial-and-error with upload caps, client portal limits, SD card space, or archive storage.

This route is built for that exact workflow. Enter the bitrate, choose Mbps or Kbps, add the duration, and it estimates the final size in MB and GB for video exports, screen recordings, audio files, and long-form deliveries. It works best when you know the combined average bitrate of the media you plan to create, including audio if that track matters.

The slug is `bitrate-to-filesize`, but the real search problem is closer to `video file size calculator` and `video bitrate calculator`. The page therefore focuses on the creator use case: turning bitrate plus runtime into a practical size estimate you can use for storage, upload, and delivery planning before the export finishes.

How to use this calculator

Enter the average bitrate of the file you plan to create. For video, use the combined average bitrate when possible so the estimate reflects both video and audio rather than video alone.
Choose the bitrate unit: Mbps for most video export workflows, or Kbps for audio files and low-bitrate media.
Enter the runtime in minutes. If you know the duration in hours, multiply by 60 first before entering it here.
Review the estimated size in MB and GB, then compare it against upload caps, storage limits, or delivery requirements.
If the file looks too large, lower the bitrate or shorten the runtime and rerun the estimate. If it looks comfortably below your cap, you may have room for higher quality or extra headroom.
When you are close to a hard limit, leave margin for VBR variation, container overhead, metadata, and any extra audio or subtitle tracks.

Inputs explained

Bitrate: The average data rate for the media you plan to create. For video, this is usually the target or average bitrate from your encoder. For audio-only workflows, you might enter values like 128 Kbps or 320 Kbps.
Bitrate unit: Select Mbps for most HD/4K video exports and Kbps for audio files or very low-bitrate media. The route converts whichever unit you choose into bits per second internally before doing the size math.
Duration (minutes): The total runtime of the file in minutes. Convert hours to minutes before entering, and use the full planned runtime rather than a rough clip length if you are trying to stay under a hard limit.

Outputs explained

File size (MB): The estimated file size in decimal megabytes. This is useful when you are checking attachment limits, upload caps, or smaller export targets.
File size (GB): The same estimate expressed in decimal gigabytes. This is usually the better number for longer videos, archive planning, SSD budgeting, and larger client deliveries.

How it works

Bitrate is a data rate per second. A 5 Mbps encode uses about five million bits every second on average, while a 128 Kbps audio file uses about 128,000 bits every second.

The calculator converts your selected bitrate into bits per second using decimal units: `Mbps × 1,000,000` or `Kbps × 1,000`.

It converts your runtime from minutes into seconds by multiplying by `60`.

Total file bits are estimated as `bits per second × total seconds`. That total is then divided by `8` to convert bits into bytes.

The byte total is expressed in decimal MB and GB so you can compare it with storage budgets, upload caps, and archive planning numbers. In this route, `1 MB = 1,000,000 bytes` and `1 GB = 1,000,000,000 bytes`.

The relationship is linear: double the bitrate and the estimated file size doubles; double the duration and the estimated file size also doubles. That makes the route useful for fast scenario planning when you are trading off quality, runtime, and file size.

This route estimates size from an average bitrate you already know or have chosen. It does not automatically pick the right bitrate for a target platform or calculate the inverse target bitrate from a size limit.

Formula

Let R = bitrate
Let unit = Mbps or Kbps
Let T = durationMinutes

Seconds = T × 60
BitsPerSecond = R × 1,000,000 if unit = Mbps, or R × 1,000 if unit = Kbps
TotalBits ≈ BitsPerSecond × Seconds
TotalBytes ≈ TotalBits ÷ 8
MB ≈ TotalBytes ÷ 1,000,000
GB ≈ TotalBytes ÷ 1,000,000,000

Quick rule of thumb: 1 Mbps sustained for 1 minute is about 7.5 MB.

When to use it

Planning video export sizes before rendering so you do not overshoot a client portal upload cap or a platform file-size limit.
Estimating how much SSD, SD card, or NAS space a shoot day or batch of recordings will consume at a chosen bitrate.
Comparing 8 Mbps, 12 Mbps, and 20 Mbps export options to see how much file-size growth you get for the extra bitrate.
Checking whether an audio-only recording, podcast, or lecture file will fit inside a distribution or storage budget.
Connecting export size to delivery planning by pairing the result with upload-time or backup-time calculations.
Explaining quality-versus-size tradeoffs to teammates or clients before you commit to a long encode or delivery workflow.

Tips & cautions

If your encoder gives separate video and audio bitrates, add them together before estimating size. File size is driven by total average bitrate, not just the video track.
Remember the quick mental rule: `1 Mbps for 1 minute is about 7.5 MB`. That makes it easier to sanity-check the outputs and spot impossible numbers.
Most real-world exports use variable bitrate, so the actual average bitrate can land above or below the nominal target. Leave a safety margin under hard size caps.
Long-form content magnifies small bitrate choices. Dropping a two-hour export from 12 Mbps to 10 Mbps saves far more space than trimming a few seconds off the runtime.
Codec choice still matters. Two files at the same bitrate can look very different depending on the codec, encoder settings, resolution, and scene complexity, even if the estimated size is identical.
Once you know the size, pair the result with upload-time or backup-time planning so you can estimate both storage impact and delivery timing.
Assumes a constant average bitrate over the full duration and does not attempt to predict how VBR or scene complexity will change size.
Ignores container overhead, metadata, subtitles, chapter markers, and extra audio tracks unless you manually account for them in the bitrate input.
Uses decimal megabytes and gigabytes (MB/GB) rather than binary MiB/GiB. Some operating systems and apps label sizes differently, so the reported disk size may not match exactly.
Does not calculate the inverse problem automatically. If you need the maximum bitrate for a target file size, you must rearrange the same formula and solve for bitrate.
Provides planning guidance only and should not be used as a strict guarantee of final file size for compliance-critical workflows.
Does not model codec efficiency, quality settings, or platform-specific recommended bitrates; it only converts an average bitrate plus runtime into a size estimate.

Worked examples

8.128 Mbps for 15 minutes (video plus 128 Kbps audio)

Suppose the video target is 8 Mbps and audio adds another 128 Kbps, for a combined bitrate of 8.128 Mbps.
Seconds = 15 × 60 = 900 seconds.
BitsPerSecond ≈ 8.128 × 1,000,000 = 8,128,000 bits/second.
TotalBits ≈ 8,128,000 × 900 = 7,315,200,000 bits.
MB ≈ 7,315,200,000 ÷ (8 × 1,000,000) ≈ 914.4 MB.
GB ≈ 914.4 ÷ 1,000 ≈ 0.9144 GB.
Interpretation: a short client delivery at this bitrate lands just under 1 GB, which may matter for portal limits or fast-turn uploads.

128 Kbps for 60 minutes (audio-only export)

Bitrate = 128 Kbps, duration = 60 minutes.
Seconds = 60 × 60 = 3,600 seconds.
BitsPerSecond ≈ 128 × 1,000 = 128,000 bits/second.
TotalBits ≈ 128,000 × 3,600 = 460,800,000 bits.
MB ≈ 460,800,000 ÷ (8 × 1,000,000) ≈ 57.6 MB.
GB ≈ 57.6 ÷ 1,000 ≈ 0.0576 GB.
Interpretation: even a full hour of compressed audio can stay relatively small compared with video files at modern export bitrates.

12 Mbps for 120 minutes (long-form HD video)

Bitrate = 12 Mbps, duration = 120 minutes.
Seconds = 120 × 60 = 7,200 seconds.
BitsPerSecond ≈ 12 × 1,000,000 = 12,000,000 bits/second.
TotalBits ≈ 12,000,000 × 7,200 = 86,400,000,000 bits.
MB ≈ 86,400,000,000 ÷ (8 × 1,000,000) ≈ 10,800 MB.
GB ≈ 10,800 ÷ 1,000 ≈ 10.8 GB.
Interpretation: long-form exports create storage pressure quickly, which is why bitrate decisions matter much more on a two-hour project than on a short clip.

25 Mbps for 45 minutes (higher-bitrate master or mezzanine)

Bitrate = 25 Mbps, duration = 45 minutes.
Seconds = 45 × 60 = 2,700 seconds.
BitsPerSecond ≈ 25 × 1,000,000 = 25,000,000 bits/second.
TotalBits ≈ 25,000,000 × 2,700 = 67,500,000,000 bits.
MB ≈ 67,500,000,000 ÷ (8 × 1,000,000) ≈ 8,437.5 MB.
GB ≈ 8,437.5 ÷ 1,000 ≈ 8.4375 GB.
Interpretation: higher bitrates can make a single export several gigabytes larger, which affects both upload time and archive planning.

Deep dive

Use this video file size calculator to estimate how large an export will be from its average bitrate and runtime before you start the render.

Enter Mbps or Kbps plus duration in minutes to estimate file size in MB and GB for video exports, audio files, uploads, storage budgets, and client deliveries.

The route also supports adjacent `video bitrate calculator` intent by showing exactly how bitrate turns into file size and by helping creators compare bitrate choices before they encode.

Methodology & assumptions

The calculator reads three values: bitrate, bitrate unit, and duration in minutes.
If the selected unit is `Mbps`, the route multiplies the bitrate by `1,000,000` to get bits per second. If the selected unit is `Kbps`, it multiplies by `1,000` instead.
The duration is converted from minutes into seconds by multiplying by `60`.
Total file bits are estimated as `bitsPerSecond × durationSeconds`.
The route converts total bits into total bytes by dividing by `8`, then reports decimal megabytes and gigabytes by dividing by `1,000,000` and `1,000,000,000` respectively.
The route intentionally uses decimal MB and GB labels because that matches the live `bitrateToFilesizeCalculator` logic and many storage/export planning conversations.
The tool assumes an average bitrate across the full runtime. It does not try to simulate scene-by-scene bitrate swings, codec efficiency, or file-container overhead beyond the core bit-to-byte conversion.
Page copy, examples, and FAQs are kept aligned with `bitrateToFilesizeCalculator` so the editorial explanation matches the live computation rather than a different export model.

Sources

NIST Guide to the SI — Appendix B: Conversion FactorsUsed for the decimal unit conventions behind MB and GB in the route copy.
NIST CSRC Glossary — MbpsUsed for the definition of megabits per second as the core bitrate unit referenced on the page.
BIPM — SI BrochureBackground reference for SI prefixes and unit framing used in the methodology and formula.

FAQs

Is this estimate exact?: No. It is a practical approximation based on average bitrate and duration. Real files will differ slightly due to container overhead, headers, timecode, subtitles, and how your encoder implements variable bitrate.
Should I use Mbps or Kbps for video?: Most modern video workflows quote bitrates in Mbps, especially for HD and 4K content. Use Kbps when working with audio-only streams or very low-resolution video where bitrates are in hundreds of kilobits per second.
How do I include audio bitrate in the estimate?: Add the average audio bitrate to the average video bitrate before you enter the number if you want the file-size estimate to reflect the full media package. For example, an 8 Mbps video plus 128 Kbps audio is about 8.128 Mbps total.
Why is the actual export sometimes larger or smaller than the estimate?: Most encoders use variable bitrate, container overhead varies, and extra tracks or metadata add data beyond the core video stream. Treat the output as a planning estimate, not a guaranteed final byte count.
Can I use this for streaming bandwidth planning?: Yes, as a directional guide. Multiply the estimated file size by expected views or use bitrate directly with viewer hours to budget total data transfer, then compare against CDN or cloud egress pricing.
Why does my OS show a slightly different size?: Operating systems sometimes report sizes in binary units (MiB/GiB: 1,048,576 bytes per MiB) instead of decimal MB/GB. This, plus metadata overhead, explains small differences between the estimate and what you see on disk.
Does this handle multiple audio tracks and subtitles?: Indirectly. You can increase the bitrate input slightly or add rough estimates for extra tracks to approximate their impact, but the calculator does not model each track separately.
Can this tell me the bitrate I need to hit a target file size?: Not directly. This route solves the forward problem: bitrate plus duration to file size. If you need the inverse, rearrange the same formula or use a dedicated target-bitrate calculator.

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This video file size calculator provides an approximate size based on user-entered bitrate, unit, and duration using simplified decimal conversions. It does not simulate codec behavior, variable bitrate swings, container overhead, or platform-specific export rules, and it should not be treated as a guaranteed compliance check for strict file-size limits. Leave safety margin and verify actual results with test encodes when the limit matters.