Video File Size Calculator

Estimate video file size from duration, video bitrate, and audio bitrate. Compare decimal GB and binary GiB before recording, exporting, uploading, or planning storage.

What Is a Video File Size Calculator?

A video file size calculator estimates how much storage a video will require based on its duration and bitrate.

This is useful when planning:

• Camera and screen recordings
• Video editing projects
• YouTube uploads
• Livestream archives
• Podcast videos
• Online courses
• Client delivery files
• Cloud storage
• Backup drives
• Upload and transfer times

Video resolution alone cannot determine file size. Two videos with the same resolution and duration can have very different file sizes if they use different bitrates, codecs, audio settings, or compression methods.

This calculator uses video duration, video bitrate, and audio bitrate to produce a practical storage estimate. All calculations run locally in your browser, and no media file needs to be uploaded.

How to Use the Video File Size Calculator

Enter the video duration

Enter the complete duration using the hours, minutes, and seconds fields.

For a 90-minute video, you can enter:

Hours: 1
Minutes: 30
Seconds: 0

For a short 45-second social media video, enter:

Hours: 0
Minutes: 0
Seconds: 45

Enter the video bitrate

Enter the video bitrate in megabits per second, abbreviated as Mbps.

For example:

Video bitrate: 8 Mbps

The video bitrate usually accounts for most of the final file size. Increasing it generally increases the amount of data stored for each second of video.

Enter the audio bitrate

Enter the audio bitrate in kilobits per second, abbreviated as kbps.

Common export settings may include values such as:

• 96 kbps
• 128 kbps
• 192 kbps
• 256 kbps
• 320 kbps

If the video does not include audio, enter 0.

Calculate the estimated size

Select Calculate file size to display:

• Estimated file size
• Decimal file size in GB
• Binary file size in GiB
• Combined video and audio bitrate
• Storage required per minute

Use Reset to return to the default values. Use Copy result to copy a summary of the estimate.

Video File Size Formula

The calculator first converts the video and audio bitrates into the same unit.

Because the video bitrate is entered in Mbps and the audio bitrate is entered in kbps, the audio value is divided by 1,000.

Total bitrate in Mbps
= Video bitrate in Mbps + (Audio bitrate in kbps ÷ 1,000)

The total number of bits is then calculated from the bitrate and duration.

Total bits
= Total bitrate in Mbps × 1,000,000 × Duration in seconds

There are eight bits in one byte, so the result is divided by eight.

File size in bytes
= Total bits ÷ 8

The final number of bytes can then be converted into MB, GB, MiB, or GiB.

Example: One-Hour Video at 8 Mbps

Consider a one-hour video with the following settings:

Duration: 1 hour
Video bitrate: 8 Mbps
Audio bitrate: 192 kbps

First, convert the audio bitrate to Mbps:

192 kbps ÷ 1,000 = 0.192 Mbps

Add the video and audio bitrates:

8 Mbps + 0.192 Mbps = 8.192 Mbps

Convert one hour to seconds:

1 hour = 3,600 seconds

Calculate the total number of bits:

8.192 × 1,000,000 × 3,600
= 29,491,200,000 bits

Convert bits to bytes:

29,491,200,000 ÷ 8
= 3,686,400,000 bytes

The estimated file size is therefore:

3.6864 GB

The same number of bytes is approximately:

3.433 GiB

The calculator may display the primary result as approximately 3.69 GB.

GB vs. GiB: Why Two Results Are Displayed

GB and GiB are not identical units.

Gigabyte

A decimal gigabyte uses powers of 1,000.

1 GB = 1,000,000,000 bytes

Storage manufacturers and many network-related calculations commonly use decimal units.

Gibibyte

A binary gibibyte uses powers of 1,024.

1 GiB = 1,073,741,824 bytes

Some operating systems and storage utilities use binary calculations, even when the interface displays a label that users interpret as gigabytes.

Because a GiB contains more bytes than a GB, the numerical GiB value is lower for the same file.

For example:

3,686,400,000 bytes = 3.6864 GB
3,686,400,000 bytes ≈ 3.433 GiB

OutputMath displays both values so you can compare decimal storage estimates with binary storage measurements.

How Bitrate Affects Video File Size

Bitrate describes the amount of data used during each second of media.

A bitrate of 8 Mbps means that approximately eight million bits of video data are used per second, before adding audio and container overhead.

For videos of equal duration, file size increases approximately in direct proportion to bitrate.

If the total bitrate doubles, the estimated file size also doubles.

For example, excluding small differences caused by audio and container data:

• 4 Mbps uses about half as much storage as 8 Mbps
• 8 Mbps uses about twice as much storage as 4 Mbps
• 20 Mbps uses about 2.5 times as much storage as 8 Mbps
• 40 Mbps uses about twice as much storage as 20 Mbps

This relationship makes bitrate the most useful input for estimating a compressed video file’s size.

Estimated Storage per Hour

The following examples include a 192 kbps audio track.

These values are bitrate-based estimates. The final exported file may be slightly different because of variable bitrate behavior, metadata, subtitles, multiple audio tracks, and container overhead.

Constant Bitrate vs. Variable Bitrate

Constant bitrate

Constant bitrate, or CBR, attempts to use a relatively consistent amount of data throughout the video.

A bitrate-based file size estimate is usually straightforward for CBR media because the data rate remains close to the selected value.

CBR is often used when predictable bandwidth or a stable data rate is important, particularly in some streaming and broadcasting workflows.

However, an encoder may not maintain a perfectly identical bitrate during every moment of the file.

Variable bitrate

Variable bitrate, or VBR, changes the data rate according to the complexity of the content.

A simple scene with limited movement may use less data. A detailed scene with rapid movement, noise, particles, camera motion, or changing textures may use more data.

When calculating a VBR file, enter the expected average bitrate rather than the maximum bitrate.

If an export application displays both a target bitrate and a maximum bitrate, the target bitrate is generally more useful for estimating final file size. The maximum value describes an upper limit and is not necessarily sustained throughout the video.

Two-pass VBR can analyze the content before completing the final encode. This may distribute the available bitrate more efficiently, but the final storage requirement still depends primarily on the achieved average bitrate and duration.

Does Resolution Determine File Size?

Resolution affects the number of pixels in each frame, but it does not directly determine the size of a compressed video file.

A 1920 × 1080 video and a 3840 × 2160 video could theoretically have the same file size if they have the same duration and average total bitrate.

However, the 4K version would need to represent more pixels with the same amount of data. Depending on the codec and content, this could reduce image quality.

In practical export workflows, higher-resolution and higher-frame-rate videos are often assigned higher bitrates. This is why 4K files are commonly larger than 1080p files, even though resolution is not included directly in the file size formula.

The calculator asks for bitrate instead of resolution because bitrate determines how much compressed data is written over time.

Does Frame Rate Affect File Size?

Frame rate does not appear directly in a bitrate-based file size calculation.

If two videos have the same duration and average bitrate, their estimated file sizes will be similar even if one is 30 fps and the other is 60 fps.

Frame rate can still affect quality requirements. A 60 fps video contains twice as many frames per second as a 30 fps video. Maintaining similar visual quality may therefore require a higher bitrate, especially when the footage contains fast movement.

Frame rate influences the bitrate you may choose, while the selected or achieved bitrate determines the storage estimate.

Does the Video Codec Affect File Size?

A codec controls how video or audio is compressed and decompressed.

Examples of video codecs include:

• H.264
• HEVC or H.265
• AV1
• VP9
• ProRes
• DNxHR

A more efficient codec may produce better visual quality at the same bitrate or similar quality at a lower bitrate.

However, codec selection does not change the basic bitrate formula. A one-hour H.264 file and a one-hour AV1 file with the same average total bitrate will have approximately the same file size.

The difference is the quality that each codec can produce with that amount of data, along with factors such as encoding time, decoding requirements, hardware support, and platform compatibility.

Editing codecs such as ProRes and DNxHR often use much higher data rates than delivery codecs such as H.264, HEVC, and AV1. As a result, editing masters and intermediate files can require substantially more storage than upload-ready versions.

Video Bitrate vs. Audio Bitrate

A video file can contain several data streams.

These may include:

• One video stream
• One or more audio streams
• Subtitle streams
• Chapter information
• Metadata
• Thumbnails or attachments
• Container information

For a typical online video, the video bitrate accounts for most of the final size.

For example, an 8 Mbps video stream is equal to 8,000 kbps. A 192 kbps audio stream adds only 2.4% to that video bitrate.

Audio becomes more significant when:

• The video bitrate is very low
• Several audio tracks are included
• High-bitrate lossless audio is used
• The file contains surround sound
• The media is primarily audio with a static image

The current calculator accepts one combined audio bitrate. If your file contains multiple audio tracks, add their bitrates together before entering the value.

For example, two 192 kbps audio tracks have a combined bitrate of:

192 + 192 = 384 kbps

Enter 384 in the audio bitrate field.

Why the Actual File May Be Different

A bitrate calculator provides an estimate rather than a guaranteed final file size.

The actual result may differ because of several factors.

Variable bitrate behavior

The achieved average bitrate may be higher or lower than the target selected in the export application.

Container overhead

Formats such as MP4, MOV, MKV, and WebM contain structural information in addition to the video and audio streams.

This can include indexes, timestamps, metadata, track descriptions, and synchronization data.

Multiple media streams

Additional audio tracks, subtitle streams, attachments, or alternate video streams increase the final size.

Encoder behavior

Different encoders may interpret bitrate targets differently. Presets, quality modes, rate-control settings, keyframe intervals, and multipass encoding can affect the achieved result.

Very short videos

Container and metadata overhead represent a larger percentage of an extremely short file than of a long recording.

Rounding

Export applications and media inspection tools may display rounded bitrate values. A displayed value of 8 Mbps may represent an average that is slightly above or below exactly 8,000,000 bits per second.

For storage planning, it is sensible to leave additional free space rather than treating the estimate as an exact maximum.

How to Find a Video’s Bitrate

Check the export settings

Applications such as Adobe Media Encoder, Premiere Pro, DaVinci Resolve, OBS Studio, and HandBrake display bitrate or quality settings before export or recording.

Look for labels such as:

• Target Bitrate
• Average Bitrate
• Video Bitrate
• Audio Bitrate
• Rate Control
• Encoding Settings

Inspect an existing file

Media inspection applications can report the video and audio streams of an existing file.

FFmpeg users can inspect media with FFprobe. Graphical applications such as MediaInfo can also show stream details.

For VBR files, use the average stream bitrate or calculate the overall rate from the actual file size and duration.

Calculate bitrate from a completed file

If you already know the file size and duration, the approximate total bitrate can be calculated in reverse.

Total bitrate in bits per second
= File size in bytes × 8 ÷ Duration in seconds

To convert the result to Mbps:

Total bitrate in Mbps
= File size in bytes × 8 ÷ Duration in seconds ÷ 1,000,000

This represents the total data rate and may include video, audio, and container information.

Estimating Upload Time

File size and upload time are related, but storage units and network units must be handled carefully.

Storage is commonly measured in bytes, while internet connection speeds are normally measured in bits per second.

Because one byte contains eight bits:

Upload time in seconds
= File size in bytes × 8 ÷ Upload speed in bits per second

A 4 GB file contains approximately 32 gigabits of data.

At a stable upload speed of 20 Mbps, the theoretical transfer time is:

32,000 megabits ÷ 20 megabits per second
= 1,600 seconds

That is approximately 26 minutes and 40 seconds.

Real uploads can take longer because of network overhead, connection instability, congestion, server performance, Wi-Fi conditions, and platform processing.

Planning Storage for Multiple Videos

To estimate storage for a collection of videos, calculate one representative file and multiply the result by the expected number of files.

For example, if one video requires approximately 3.69 GB:

10 videos ≈ 36.9 GB
50 videos ≈ 184.5 GB
100 videos ≈ 369 GB

Additional capacity may be required for:

• Original camera files
• Proxy files
• Preview renders
• Project files
• Graphics and audio assets
• Cache files
• Exported masters
• Upload versions
• Backups

A production workflow may keep several versions of the same project. The storage required for the complete project can therefore be much greater than the size of the final video alone.

Need to Calculate Bitrate Instead?

Use the Video Bitrate Calculator when you know the target file size and duration but need to determine the available video bitrate.

Calculating Audio-Only File Size

For podcasts, music, voice recordings, and uncompressed PCM audio, use the Audio File Size Calculator. It supports compressed bitrate calculations and PCM settings such as sample rate, bit depth, and channel count.

Related Calculators

Video Bitrate Calculator — Calculate the video bitrate needed for a target file size and duration.

Audio File Size Calculator — Estimate compressed or uncompressed audio file size.

Aspect Ratio Calculator — Simplify aspect ratios and calculate matching video dimensions.

DPI/PPI Calculator — Calculate image resolution, PPI, and print dimensions.

Frequently Asked Questions

How large is one hour of 1080p video?

There is no single size for one hour of 1080p video because file size depends on bitrate.

At 8 Mbps video and 192 kbps audio, one hour is approximately 3.69 GB. A higher bitrate produces a larger file, while a lower bitrate produces a smaller one.

How large is one hour of 4K video?

The answer depends on the selected or achieved bitrate.

At 45 Mbps video and 192 kbps audio, one hour is approximately 20.34 GB. Professional recording formats and less-compressed camera files may be considerably larger.

Is Mbps the same as MB/s?

No.

• Mbps means megabits per second
• MB/s means megabytes per second

Because there are eight bits in one byte:

8 Mbps = 1 MB/s

Letter capitalization matters. A lowercase b represents bits, while an uppercase B represents bytes.

Why is audio entered in kbps?

Audio bitrates are usually much smaller than video bitrates and are commonly displayed in kilobits per second.

The calculator automatically converts the audio value from kbps to Mbps before adding it to the video bitrate.

Should I enter target or maximum bitrate?

For a variable-bitrate export, enter the expected average or target bitrate. Entering the maximum bitrate will usually overestimate the file size because the encoder may reach that rate only during more complex sections.

Does a higher bitrate always mean better quality?

A higher bitrate gives an encoder more data to represent the content, but quality also depends on the codec, encoder, source footage, resolution, frame rate, color settings, and compression efficiency.

Increasing bitrate beyond a useful level may produce a larger file without a noticeable improvement.

Can this calculator estimate uncompressed video?

Only if you know the total uncompressed bitrate and enter it into the bitrate fields.

Uncompressed video data rates depend on resolution, frame rate, chroma sampling, and bit depth. They can be much higher than typical compressed delivery bitrates.

Does the result include container overhead?

No. The result is based on the entered video and audio bitrates. The final file may be slightly larger because of container information, metadata, subtitles, indexes, and other streams.

Are my video files uploaded?

No video file is selected or uploaded. The calculator only processes the duration and bitrate values entered into the form, and the calculation runs in your browser.

Calculation Methodology

OutputMath calculates video file size using decimal network bitrate units.

The calculator uses:

1 kbps = 1,000 bits per second
1 Mbps = 1,000,000 bits per second
1 byte = 8 bits
1 GB = 1,000,000,000 bytes
1 GiB = 1,073,741,824 bytes

The audio bitrate is converted from kbps to Mbps and added to the video bitrate. The combined bitrate is multiplied by the duration in seconds and converted from bits to bytes.

The result does not attempt to predict codec efficiency or visual quality. It estimates storage from the data rate supplied by the user.

Container overhead, additional streams, metadata, and differences between target and achieved bitrate are not included. For critical recording or storage planning, allow additional free capacity and confirm the result with a short test recording using the intended settings.

Learn More About Video File Size

Want to estimate storage before recording or exporting? Read our guide to video file size by resolution and duration for practical estimates covering 720p, 1080p, 1440p, 4K, frame rate, audio, and codec settings.

Choosing the Right Video Bitrate

Video bitrate has a major effect on file size, upload time, and visual quality. Read our guide to the best video bitrate for 1080p, 1440p, and 4K to choose an appropriate setting for your resolution, frame rate, codec, and publishing platform.