Free Video File Size Calculator
Estimate video file size from bitrate and length, or the bitrate that fits a size limit.
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How to use this tool
Export settings list bitrate in Mbps and kbps, while upload limits and storage are in MB, so it’s hard to know whether a render will fit before you hit export. This calculator works both ways: it estimates file size from duration and bitrate, or solves the highest video bitrate that fits a target size after audio. It helps editors planning exports, creators working within upload limits and anyone sizing storage for a shoot.
- 01
Choose what to calculate
In Calculate, pick File size to estimate MB from a bitrate, or Video bitrate to find the bitrate that fits a target size. The form shows only the fields that mode needs.
- 02
Enter duration, audio and your known value
Fill in Duration (seconds) and Audio bitrate (kbps), such as 60 and 128. Then add Video bitrate (Mbps) for a size estimate, or File size (MB) for a bitrate target.
- 03
Calculate and adjust
Select Calculate to see Estimated size in MB or Video bitrate in Mbps, with the formula. Change one value to compare export settings, then select Copy.
How video file size is calculated
File size (MB) = (video bitrate in Mbps + audio bitrate in kbps ÷ 1,000) × duration in seconds ÷ 8. Bitrate is how much data each second of video uses. Adding video and audio gives the total bitrate, multiplying by duration gives total megabits, and dividing by 8 converts to megabytes. Worked example: a 10-minute (600-second) video at 8 Mbps with 128 kbps audio is 8.128 × 600 ÷ 8 = 609.6 MB.
Find the bitrate for a target file size
Video bitrate (Mbps) = target size in MB × 8 ÷ duration in seconds − audio bitrate in kbps ÷ 1,000. This tells you the highest average video bitrate that fits a size limit once audio is accounted for. Worked example: to fit a 90-second clip into 50 MB with 128 kbps audio, 50 × 8 ÷ 90 − 0.128 ≈ 4.32 Mbps. Set your encoder a little lower to leave room for container overhead. If audio alone uses up the budget, the calculator asks you to change the values.
Reference bitrates for common resolutions
YouTube’s recommended upload settings for SDR video at standard frame rates (24–30 fps), at the time of writing: • 720p: 5 Mbps • 1080p: 8 Mbps • 1440p: 16 Mbps • 4K (2160p): 35–45 Mbps High frame rates (48–60 fps) use roughly 1.5 times more, and YouTube suggests 384 kbps for stereo audio. Other platforms and editors use different targets, so check the platform’s own guidance.
Why the exported file may differ
• Variable bitrate: encoders spend more data on busy scenes and less on static ones, so the average can drift from your setting. • Container overhead: MP4 or MOV wrappers and metadata add a little on top. • Units: this calculator uses decimal MB (1 MB = 1,000,000 bytes); some operating systems display binary units, which look slightly smaller. • Encoder settings: quality-based modes like CRF don’t target a bitrate at all. Treat the result as a planning estimate and check the real file after export.
Frequently asked questions
What is a video file size calculator?
A video file size calculator estimates how much storage a video will take from its length and bitrate. This one also works in reverse, solving the video bitrate that fits a target file size after subtracting audio. Both results are planning estimates in decimal MB and Mbps.
How do I calculate video file size from bitrate?
1. Convert audio bitrate to Mbps by dividing kbps by 1,000. 2. Add it to the video bitrate. 3. Multiply by the duration in seconds. 4. Divide by 8 to get MB. For example, (5 + 0.128) × 120 ÷ 8 = 76.92 MB for a 2-minute 720p clip.
How do I calculate the bitrate for a target file size?
Switch Calculate to Video bitrate, then enter the duration, target File size (MB) and Audio bitrate (kbps). The tool multiplies MB by 8, divides by seconds and subtracts the audio share. For a 60-second, 100 MB target with 128 kbps audio, that’s about 13.21 Mbps of video.
How big is a 1-minute 1080p video?
It depends on the bitrate. At YouTube’s recommended 8 Mbps for 1080p plus 128 kbps audio, one minute is about 61 MB; at 12 Mbps for 60 fps it’s about 91 MB. Phone recordings often use different bitrates, so check the actual export settings.
What’s the difference between Mbps, kbps and MB?
Mbps (megabits per second) and kbps (kilobits per second) measure bitrate, and 1 Mbps equals 1,000 kbps. MB (megabytes) measures file size, and 1 byte is 8 bits. That’s why the formula divides by 8 when converting total megabits into megabytes.
Why is my exported video a different size than estimated?
Most encoders use variable bitrate, so the real average can land above or below your setting. Container overhead adds a little, and your computer may show binary units that look smaller. For a size closer to the estimate, use two-pass encoding with a target bitrate and check the result.
What audio bitrate should I enter?
Use the audio bitrate from your export settings. Many editors default to 128–320 kbps for stereo AAC, and YouTube’s upload guide suggests 384 kbps for stereo. If a video has no audio track, enter 0.
How do I enter a duration in minutes?
Multiply minutes by 60 and add any extra seconds. For example, 2:30 is 150 seconds and 10 minutes is 600 seconds. Enter that number in Duration (seconds).
Do I need to upload my video?
No. The calculator only uses the numbers you type and runs entirely in your browser, so no video file is opened or uploaded to a server. Read the duration and bitrate from your editor’s export settings or the file’s properties.
Is the video file size calculator free?
Yes. It’s free with no signup, login or download. Pick a mode, enter your numbers, select Calculate and compare as many export settings as you like.
For developers
Plan video content with public social data
Use SocQ APIs to pull public posts and profiles across Instagram, TikTok, YouTube and LinkedIn, so you can see which video formats perform before you settle on export settings. The APIs return public data only, not private account analytics.
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