Screen Recording File Size Calculator – Bitrate & Storage

How the Screen Recording File Size Calculator Works

The Screen Recording File Size Calculator estimates storage from:

• recording duration;
• average video bitrate;
• optional audio bitrate;
• container and metadata overhead;
• number of recordings.

It supports two calculation methods:

Known-bitrate mode is the better choice when a representative saved bitrate is already available.

Example: One Hour of Screen Recording at 8 Mbps

Suppose:

1. Combine Video and Audio Bitrates

Convert audio to Mbps:

160 kbps ÷ 1,000 = 0.16 Mbps

Combined media bitrate:

8 + 0.16 = 8.16 Mbps

2. Convert Bitrate Into Stored Bytes

One hour contains:

3,600 seconds

Because:

8 bits = 1 byte

the encoded media payload is:

8.16 × 1,000,000 × 3,600 ÷ 8

= 3,672,000,000 bytes

In decimal storage units:

= 3.672 GB

3. Apply Container and Metadata Overhead

At 2%:

3,672,000,000 × 1.02

= 3,745,440,000 bytes

Estimated file size:

• 3.75 GB
• approximately 3.49 GiB

The completed results are:

This calculation assumes that 8 Mbps reasonably represents the average video bitrate of the completed recording.

Calculate File Size From a Known Bitrate

Known-bitrate mode uses:

Combined bitrate = Video bitrate + Audio bitrate

Then:

Encoded payload bytes = Combined bitrate × Duration seconds ÷ 8

Finally:

Estimated file size = Encoded payload × (1 + Overhead % ÷ 100)

When audio is disabled:

Audio bitrate = 0

A representative bitrate can come from:

• a finished recording;
• a realistic test recording;
• a CBR target;
• an expected VBR average;
• recording-software statistics.

For variable-bitrate or quality-based recording, a representative average is generally more useful than a maximum bitrate.

The average can vary with:

• rate-control method;
• screen activity;
• visual complexity;
• encoder preset;
• codec implementation;
• quality settings.

A test recording should resemble the intended workload. A static desktop sample may not represent a future session dominated by gameplay, animation, or full-screen video.

Do Not Apply Screen-Setting Factors Twice

Once the complete average video bitrate is known, do not multiply it again by:

• resolution;
• frame rate;
• codec factor;
• quality factor;
• activity factor.

Those effects should already be reflected in the saved bitrate.

Use the Correct Bitrate Units

The video input is measured in:

Mbps = megabits per second

This differs from:

MB/s = megabytes per second

Because:

8 bits = 1 byte

then:

1 MB/s = 8 Mbps

For example:

1.5 MB/s × 8 = 12 Mbps

If software reports 1.5 MB/s but the value is entered as 1.5 Mbps, the storage estimate will be too low by a factor of eight.

For kilobits:

Mbps = kbps ÷ 1,000

So:

6,000 kbps = 6 Mbps

The calculator uses decimal bitrate conversions.

Estimate Bitrate From Screen Settings

When no representative bitrate is available, screen-settings mode builds a planning estimate from:

• screen activity;
• quality level;
• codec reference;
• resolution;
• frame rate.

The reference point is:

• 1920 × 1080
• 30 fps
• H.264
• balanced quality

Screen activity sets the starting reference:

The estimate is:

Estimated video bitrate = Activity reference × Quality factor × Codec factor × Pixel factor × Frame-rate factor

These values are transparent calculator planning assumptions, not guaranteed outputs from a specific encoder or recording application.

Calculate the Resolution Factor

Resolution is scaled from the 1920 × 1080 reference:

Pixel factor = (Selected width × Selected height) ÷ (1920 × 1080)

For UHD 4K:

3840 × 2160 = 8,294,400 pixels

For Full HD:

1920 × 1080 = 2,073,600 pixels

Therefore:

8,294,400 ÷ 2,073,600 = 4

So the calculator applies a:

4× pixel factor

to its 1080p reference.

Real compressed bitrate does not necessarily increase in exact proportion to pixel count, so this factor should be treated as a planning adjustment.

Calculate the Frame-Rate Factor

The frame-rate reference is:

30 fps

Use:

Frame-rate factor = Selected fps ÷ 30

For example:

60 ÷ 30 = 2

so the calculator applies a:

2× frame-rate factor

to the reference.

Real encoded bitrate may not scale in exact proportion to frame rate because neighboring frames can share substantial visual information.

Apply Quality and Codec Factors

Screen-settings mode provides three planning quality levels:

These multipliers create lower- or higher-data-rate planning scenarios. They are not standardized quality settings shared by all recording applications.

Codec reference factors are:

The codec factors are calculator planning references rather than guaranteed efficiency differences.

Actual compression behavior can vary with:

• encoder implementation;
• hardware or software encoding;
• preset;
• rate control;
• visual complexity;
• quality target;
• keyframe structure.

Codec Name Does Not Determine File Size by Itself

Storage follows the bitrate actually written.

If two recordings both average:

8 Mbps

for the same duration, their mathematical video payload is the same even if one uses H.264 and the other uses H.265.

A more efficient codec may allow a lower bitrate at a comparable quality target, but the codec name does not reduce storage after the bitrate is already fixed.

Understand Rate-Control Methods

Different rate-control methods affect how predictable the completed file size is.

Constant Bitrate

A CBR configuration attempts to remain near a selected bitrate, making:

bitrate × duration

a practical storage estimate.

The final average can still differ slightly from the configured target.

Variable Bitrate

VBR allows the encoder to use more data for complex content and less for simpler content.

Use the expected or measured average bitrate, not only the maximum bitrate.

Constant Quality

In quality-oriented modes such as CQP, bitrate is an output of the selected quality and the recorded content rather than a fixed target.

A coding tutorial and fast gameplay can therefore produce substantially different file sizes under similar quality-oriented settings.

OBS’s official Advanced Recording Settings Guide documents Constant QP recording and notes that lower CQ values increase quality and file size.

For quality-based recording, a representative test recording can provide a stronger known-bitrate input.

Add Saved Audio to the Video Bitrate

When audio is included, enter the combined encoded bitrate of all saved audio tracks.

These can include:

• microphone audio;
• system audio;
• application audio;
• commentary;
• other independently saved tracks.

Suppose:

• microphone audio: 128 kbps
• system audio: 160 kbps

Combined audio bitrate:

128 + 160 = 288 kbps

If both tracks are saved, enter:

288 kbps

The calculator adds the combined audio bitrate to the video bitrate before calculating the encoded media payload.

For audio-only storage or PCM calculations based on sample rate, stored bit width, and channels, use the Audio File Size Calculator.

Apply Container and Metadata Overhead

A completed screen recording can contain data beyond the encoded video and audio payload.

The optional overhead percentage can represent scalable structures such as:

• indexes;
• timestamps;
• track information;
• codec headers;
• application metadata;
• other auxiliary structures.

Use:

Overhead bytes = Encoded payload × Overhead % ÷ 100

Then:

Final file size = Encoded payload + Overhead

or equivalently:

Final file size = Encoded payload × (1 + Overhead % ÷ 100)

The overhead value is an editable planning allowance, not a universal percentage for every MP4, MKV, MOV, WebM, or recorder implementation.

Entering:

0%

returns the theoretical encoded video-and-audio payload before this allowance.

Bitrate uncertainty and container overhead are separate assumptions. If the expected bitrate is uncertain, adjust the bitrate input rather than using the overhead percentage to compensate for it.

Understand Decimal and Binary Storage Units

The same byte total can be displayed in decimal or binary units.

The opening example contains:

3,745,440,000 bytes

which is:

• 3.75 GB
• approximately 3.49 GiB

Both figures represent the same stored data.

Scale the Recording Duration

The opening one-hour example requires:

3.74544 GB

At the same average bitrate, audio bitrate, and overhead:

Two Hours

3.74544 × 2 = 7.49088 GB

Approximately:

7.49 GB

Three Hours

3.74544 × 3 = 11.23632 GB

Approximately:

11.24 GB

These projections apply only while the recording assumptions remain unchanged.

Calculate Multiple Screen Recordings

For identical recordings:

Total storage = File size per recording × Recording count

Using the one-hour example:

3.74544 GB × 10

= 37.4544 GB

Equivalent to approximately:

• 37.45 GB
• 34.88 GiB

Recording count changes the total collection size, not the size of each individual recording.

Mixed Recording Groups

The recording-count feature assumes the selected recordings share the same:

• duration;
• video bitrate or screen-settings estimate;
• audio bitrate;
• overhead percentage.

If recordings differ materially, calculate similar groups separately.

For example:

• 20 coding tutorials at 4 Mbps;
• 5 gameplay recordings at 20 Mbps;
• 10 silent captures at 3 Mbps.

Add the resulting group totals instead of forcing materially different recordings into one average.

Long Recordings May Be Split Into Multiple Files

Some applications or storage systems divide long sessions into multiple files.

Splitting usually leaves the underlying encoded media payload at a similar overall scale, but repeated per-file structures can slightly change completed storage.

The calculator models the entered total duration and proportional overhead rather than a specific application’s file-segmentation behavior.

Use a General Video Storage Model When Needed

Screen-settings mode is designed specifically around screen-content assumptions such as:

• coding;
• documents;
• scrolling;
• application use;
• video playback;
• gameplay.

For camera recordings, professional recording profiles, card-capacity comparisons, or broader video-storage planning, use the Video Recording Storage Calculator.

Software Input Limits

These are calculator validation limits, not recommended recording settings.

Calculation Boundaries

The Screen Recording File Size Calculator estimates storage from the supplied assumptions.

It does not:

• inspect an actual recording;
• encode video;
• determine visual quality;
• verify whether a device can encode the selected settings;
• estimate CPU or GPU requirements;
• predict dropped frames;
• calculate upload time;
• include editing-project or temporary-cache storage;
• inspect remaining physical disk capacity;
• reproduce the exact behavior of a specific encoder.

Actual storage depends on how closely the saved recording matches the entered assumptions.

Calculation Method

Known-Bitrate Mode

Combined bitrate = Video bitrate + Audio bitrate

Encoded payload bytes = Combined bitrate × Duration seconds ÷ 8

Final file size = Encoded payload × (1 + Overhead % ÷ 100)

Screen-Settings Mode

Estimated video bitrate = Activity reference × Quality factor × Codec factor × Pixel factor × Frame-rate factor

Where:

Pixel factor = Selected pixel count ÷ 1080p pixel count

and:

Frame-rate factor = Selected fps ÷ 30

Multiple Identical Recordings

Total storage = File size per recording × Recording count

The calculator performs these calculations from the underlying values. Display precision changes only how the results are shown.