Quick answer
File size in bytes = bitrate (bits per second) × duration (seconds) ÷ 8. A 128 kbit/s stream of 3 minutes 30 seconds is 3,360,000 bytes: 3.36 MB or 3.204 MiB.
Enter a bitrate and a duration in hours, minutes and seconds. The calculator returns the size in several units. Use this media file size calculator to check your own figures.
Related tools: Bitrate Calculator: Average bitrate of a file from its size and duration. Data Transfer Calculator: Amount of data moved at a speed over a time. Download Time Calculator: Time to download a file at a given speed.
How to use the Media File Size Calculator
- Enter bitrate (0.001 or more).
- Choose bitrate unit: kilobits per second and megabits per second.
- Enter hours (a whole number, between 0 and 999). It starts at 0.
- Enter minutes (a whole number, between 0 and 59). It starts at 0.
- Enter seconds (between 0 and 59.999). It starts at 0.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Bitrate | A number | ≥ 0.001 |
| Bitrate unit | Choose one: kilobits per second; megabits per second | Starts at kilobits per second |
| Hours | A whole number | ≥ 0, ≤ 999, starts at 0 |
| Minutes | A whole number | ≥ 0, ≤ 59, starts at 0 |
| Seconds | A number | ≥ 0, ≤ 59.999, starts at 0 |
Formula and method
Formula
size (bytes) = bitrate (bits/s) × duration (s) ÷ 8
IEEE-754 double precision; shown to at most 6 decimal places.
The size of a constant-bitrate stream: bits per second times seconds, divided by 8 bits per byte. Decimal units (kilo = 1,000, as on drive labels) and binary units (KiB = 1,024) are both shown. Variable-bitrate files use the average bitrate; container overhead, subtitles and extra tracks add a little, so real files are slightly larger.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Bitrate = 128; Bitrate unit = kilobits per second; Hours = 0; Minutes = 3; Seconds = 30.
| Result | Value |
|---|---|
| File size | 3.36 MB |
| Gigabytes (decimal) | 0.0034 GB |
| Mebibytes (binary) | 3.204 MiB |
| Gibibytes (binary) | 0.0031 GiB |
| Bytes | 3,360,000 |
Example 2
Inputs: Bitrate = 8; Bitrate unit = megabits per second; Hours = 1; Minutes = 30; Seconds = 0.
| Result | Value |
|---|---|
| File size | 5,400 MB |
| Gigabytes (decimal) | 5.4 GB |
| Mebibytes (binary) | 5,149.841 MiB |
| Gibibytes (binary) | 5.0291 GiB |
| Bytes | 5,400,000,000 |
Example 3
Inputs: Bitrate = 320; Bitrate unit = kilobits per second; Hours = 0; Minutes = 0; Seconds = 59.5.
| Result | Value |
|---|---|
| File size | 2.38 MB |
| Gigabytes (decimal) | 0.0024 GB |
| Mebibytes (binary) | 2.27 MiB |
| Gibibytes (binary) | 0.0022 GiB |
| Bytes | 2,380,000 |
The first line is the headline result (file size). Below it the media File Size Calculator lists gigabytes (decimal), mebibytes (binary), gibibytes (binary) and bytes, which describe the same case from other angles. IEEE-754 double precision; shown to at most 6 decimal places.
Worked example
128,000 bit/s × 210 s = 26,880,000 bits, and ÷ 8 = 3,360,000 bytes. In binary units that is 3.204 MiB.
What it leaves out
Only a constant average bitrate is covered, and container overhead (headers, metadata) is not included. Use the Audio File Size or Video File Size pages if you want separate audio and video rates.
How the result changes with bitrate
Holding every other input at the first worked example, this table changes only bitrate. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Bitrate | File size | Gigabytes (decimal) | Mebibytes (binary) |
|---|---|---|---|
| 64 | 1.68 MB | 0.0017 GB | 1.602 MiB |
| 128 | 3.36 MB | 0.0034 GB | 3.204 MiB |
| 256 | 6.72 MB | 0.0067 GB | 6.409 MiB |
| 512 | 13.44 MB | 0.0134 GB | 12.817 MiB |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Bitrate: left empty shows "Enter bitrate." beside that field and no result.
- Seconds: entering "0" shows "Enter a duration above zero." beside that field and no result.
Choosing between the Media File Size Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Bitrate Calculator](/technology/bitrate-calculator/) | file size, size unit and duration | Average bitrate |
| [Data Transfer Calculator](/technology/data-transfer-calculator/) | speed, speed unit and duration | Data transferred |
| [Download Time Calculator](/technology/download-time-calculator/) | file size, size unit and connection speed | Time |
| [Bandwidth Calculator](/technology/bandwidth-calculator/) | data size, size unit and time allowed | Bandwidth required |
| [Audio File Size Calculator](/technology/audio-file-size-calculator/) | bitrate and duration | File size |
Background: networking and display
Network speeds are quoted in bits per second and file sizes in bytes, and a byte is 8 bits, so a 100 Mbps link moves at most 12.5 megabytes per second; real throughput is usually below the advertised rate. Pixel density is the diagonal in pixels divided by the diagonal in inches: a 1920×1080 display of 24 inches is about 92 pixels per inch, and a 3840×2160 display of 27 inches about 163.
Assumptions and limitations
- Constant (average) bitrate only
- Container overhead is not included
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for bitrate and seconds to confirm this.
Frequently asked questions
How big is an hour at 128 kbit/s?
128 kbit/s × 3,600 s ÷ 8 = 57.6 MB for an hour.
Is the size decimal or binary?
Both are shown: decimal MB/GB and binary MiB/GiB, e.g. 3.36 MB is 3.204 MiB.
Does variable bitrate change it?
The average bitrate still gives a close estimate.
What does the Media File Size Calculator calculate?
File size of an audio or video stream from its bitrate and duration. It returns File size, Gigabytes (decimal), Mebibytes (binary), Gibibytes (binary) and Bytes.
What formula does the Media File Size Calculator use?
size (bytes) = bitrate (bits/s) × duration (s) ÷ 8. The size of a constant-bitrate stream: bits per second times seconds, divided by 8 bits per byte.
What do I need to enter in the media File Size Calculator?
You enter Bitrate, Bitrate unit, Hours, Minutes and Seconds.
How is the result rounded or limited?
IEEE-754 double precision; shown to at most 6 decimal places. Constant (average) bitrate only.
What are the limits of this calculator?
Constant (average) bitrate only. Container overhead is not included.
What does the “Bitrate unit” option change?
It sets how the media File Size is worked out. The choices are kilobits per second and megabits per second.
What is an example of a media File Size result?
With bitrate 128, bitrate unit kilobits per second, hours 0, minutes 3 and seconds 30, the file size is 3.36 MB.
Where does the method come from?
The method follows: Definition of bit rate; decimal prefixes (SI) and binary prefixes (IEC 80000-13).
Related calculators
- Bitrate Calculator — Average bitrate of a file from its size and duration.
- Data Transfer Calculator — Amount of data moved at a speed over a time.
- Download Time Calculator — Time to download a file at a given speed.
- Bandwidth Calculator — Bandwidth needed to move a file in a given time.
- Audio File Size Calculator — File size of audio at a constant bitrate.
- Video File Size Calculator — File size of video with audio at constant bitrates.
- Screen Size Calculator — Width, height and area of a screen from its diagonal and aspect ratio.
- Binary Calculator — Add, subtract, multiply, divide or apply bitwise operations to binary numbers.
Sources
- Definition of bit rate; decimal prefixes (SI) and binary prefixes (IEC 80000-13)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.