How big will my video file be?

Multiply your video bitrate plus audio bitrate (in Mbps) by the duration in seconds, then divide by 8 to get megabytes. An 8 Mbps 1080p video with 128 kbps audio for 10 minutes comes out to roughly 610 MB.

What is Bits-Per-Pixel (bpp) and what is a good value?

Bits-Per-Pixel (bpp) measures compression density: bpp = bitrate (bps) / (width × height × frame rate). Values below 0.05 often show visible compression artifacts, 0.07 to 0.10 provide good web streaming quality, and 0.10 to 0.18 deliver excellent YouTube/Vimeo upload quality.

What's the best bitrate for 4K YouTube?

YouTube's current guidance is roughly 45 Mbps for 4K (2160p) SDR at 24-30fps and around 68 Mbps at 48-60fps; the corresponding HDR figures are about 56 and 85 Mbps. Use the Platform Presets tab for the recommendation matching your resolution and frame rate, and recheck YouTube's help page before a major upload.

How much smaller is H.265 than H.264?

At the same visual quality, H.265 (HEVC) typically needs about half the bitrate of H.264, so the file is roughly half the size. AV1 goes further, often needing 30-50% less than H.265.

Is AV1 always the better choice?

AV1 produces the smallest files at a given quality, but it encodes much slower than H.264 or H.265 and has less universal hardware playback support. For maximum compatibility, H.264 is still the safest choice; H.265 is a good middle ground.

Does the audio track add much to the file size?

Usually only a small amount. A typical 128-384 kbps audio track adds roughly 1-3 MB per minute, far less than the video track at typical bitrates — but it's still counted in every size calculation here.

Video Bitrate & File Size Calculator

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Walk-through

How to Use This Calculator

5 steps

1

Pick a mode

Choose File Size & Quality to calculate size and Bits-Per-Pixel compression density, Target Size Solver to work backward from an upload limit (like Discord or WhatsApp), Platform Presets for recommended streaming bitrates, or Storage & Recording Time to see how much footage fits on a memory card.

2

Set resolution, frame rate, and duration

These live in the Video Settings card and apply across every mode — pick your resolution, frame rate, and duration in minutes or hours/minutes/seconds. Higher resolutions and frame rates require more bitrate to maintain clear motion.

3

Enter your bitrate, target size, or storage capacity

On File Size, enter the video bitrate or click a bpp quality target; on Target Size Solver, click an upload limit preset (such as Discord 10 MB or Email 25 MB); on Storage & Recording Time, pick your SD card or SSD size (like 128 GB).

4

Read the result and quality gauge

The result card shows estimated file size, required bitrate, or available recording hours, plus compression density (Bits-Per-Pixel) and data rate per hour.

5

Compare codecs and export

Review the scenario comparison table to see how H.264, H.265 (HEVC), AV1, VP9, and Apple ProRes 422 compare, and export your calculations to CSV or copy a summary to your clipboard.

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Reference

Formula & Methodology

5 formulas

File size from bitrate and duration

size (MB) = ((video Mbps + audio Mbps) × duration in seconds) ÷ 8

Bitrate is measured in megabits per second; dividing total bits by 8 converts to megabytes. Audio bitrate (typically 128-384 kbps) is converted to Mbps and added to the video bitrate before multiplying by duration.

Target size to required bitrate

required video Mbps = (target size MB × 8 ÷ duration in seconds) − audio Mbps

This inverts the file size formula to solve for the video bitrate that hits a specific upload cap, after subtracting out the audio track's share. If the target size is too small for the duration and audio alone, the required bitrate clamps to zero.

Bits-Per-Pixel (bpp) compression density

bpp = video bitrate (bps) ÷ (width × height × frame rate)

Bits-Per-Pixel measures how much data is allocated to each pixel in every second of video. Values below 0.05 bpp indicate heavy compression with potential motion blocking; 0.07 to 0.10 bpp provides good web streaming quality; 0.10 to 0.18 bpp delivers high-fidelity YouTube/Vimeo upload quality; and values above 0.20 bpp represent near-lossless archival quality.

Storage media recording time

recording time (hours) = (usable storage GB × 8000) ÷ (total bitrate Mbps × 3600)

The calculator uses decimal SI units: 1 GB = 1,000 MB = 1,000,000,000 bytes, and 1 Mbps = 1,000,000 bits per second. Convert usable GB to megabits by multiplying by 8,000, then divide by total Mbps × 3,600. The safety margin is a planning allowance; actual formatted capacity and overhead vary.

Codec efficiency comparison

equivalent bitrate = (entered bitrate ÷ codec multiplier) × target codec multiplier

H.265 typically needs about half the bitrate of H.264 for the same visual quality (multiplier 0.5), and AV1 needs roughly 30-50% less than H.265 (multiplier 0.4). The calculator normalizes your entered bitrate to an H.264-equivalent baseline, then scales it to each codec to show what the same visual quality would cost in bitrate and storage.

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Glossary

Key Terms Explained

9 terms

Bitrate The amount of data processed per second of video or audio, usually measured in megabits per second (Mbps) for video and kilobits per second (kbps) for audio. Higher bitrate preserves finer detail and smoother motion at the expense of larger file size.

Bits Per Pixel (bpp) A standard video engineering metric that normalizes bitrate across different resolutions and frame rates. Calculated as video bitrate (in bits/sec) divided by (horizontal pixels × vertical pixels × frames/sec). It allows fair quality comparisons between a 1080p 30fps clip and a 4K 60fps clip.

Apple ProRes An intra-frame compression codec developed by Apple for video editing and post-production. Unlike inter-frame delivery codecs (H.264/H.265), ProRes compresses each frame independently, delivering exceptional visual fidelity and smooth timeline scrubbing at the cost of much larger file sizes.

VP9 An open and royalty-free video coding format developed by Google, widely used on YouTube and modern web browsers. VP9 provides roughly 40-50% bitrate reduction compared to H.264 at equivalent visual quality, serving as the bridge to AV1.

CBR vs. VBR Constant bitrate (CBR) keeps the data rate fixed throughout the video, making bandwidth and storage predictable — the standard choice for live streaming. Variable bitrate (VBR) dynamically allocates more data to high-motion scenes and less to static scenes, yielding smaller files at equivalent average quality.

Resolution The pixel dimensions of the video (e.g., 1920×1080 for 1080p Full HD, 3840×2160 for 4K UHD). Higher resolution displays more visual detail but requires proportionately more bitrate to prevent compression artifacts.

Frame rate The number of distinct images displayed per second (fps). Standard cinematic video runs at 24 fps, broadcast and web video at 30 fps, and gaming or sports at 60 or 120 fps. Higher frame rates require 30-50% more bitrate to maintain the same visual quality.

Codec The compression algorithm used to encode and decode video, such as H.264, H.265, AV1, or ProRes. More efficient codecs compress video into smaller files at equivalent quality, but require more processing power to encode and play back.

Storage Headroom A reserved buffer (typically 5% to 15%) subtracted from total storage card capacity to account for filesystem formatting, partition overhead, and camera metadata, preventing unexpected card-full errors during recording.

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Scenarios

Real-World Examples

4 worked examples

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YouTube creator exporting a 1080p video

File Size mode — checking upload size and compression density before exporting

Resolution 1080p FHD Frame rate 30 fps Video bitrate 8 Mbps Duration 10 min

At 8 Mbps video plus 128 kbps audio for 10 minutes, the file comes out to about 610 MB. The Bits-Per-Pixel density is 0.129 bpp, placing it firmly in the High Quality upload tier recommended by YouTube and Vimeo.

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Uploader with a 500 MB Discord Nitro cap

Target Size Solver mode — fitting a 30-minute gaming clip under 500 MB

Target file size 500 MB Duration 30 min Audio bitrate 128 kbps

To land precisely under 500 MB over 30 minutes, encode at roughly 2.09 Mbps video bitrate. For a 1080p 60fps clip this will show compression artifacts, so dropping the resolution to 720p or switching to H.265 is strongly recommended.

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Editor comparing H.264 against H.265 and AV1

Codec comparison — maximizing quality while minimizing storage

Video bitrate (H.264) 8 Mbps Codec H.264 → H.265 / AV1 Duration 10 min

Re-encoding an 8 Mbps H.264 video into H.265 at equivalent visual quality requires only 4 Mbps, reducing file size from 610 MB down to roughly 310 MB. Encoding in AV1 drops it even further to about 250 MB.

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Videographer planning card storage for an event shoot

Storage & Recording Time mode — checking how many hours fit on a 128 GB SD card

Media capacity 128 GB Recording bitrate 100 Mbps (4K 60fps All-I) Safety margin 5% Audio bitrate 0 kbps

With 121.6 GB of usable space and a total bitrate of 100 Mbps, the card holds about 2 hours and 42 minutes. Data consumption is 45 GB per hour using decimal units.

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Reference

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Use either format to cite this calculator in a paper, report, or resource list.

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Deep Dive

The Complete Guide to Video Bitrates, File Sizes, and Encoding Quality

5 chapters · 5 min read

Whether you are exporting a short social media clip to meet a strict 25 MB email limit, configuring OBS for a smooth 1080p 60fps Twitch stream, or calculating how many hours of 4K footage will fit on a 128 GB memory card, the relationship between resolution, frame rate, bitrate, and codec efficiency governs everything. This calculator provides a unified workspace for all four sides of video data planning.

File size is simply bitrate times duration

Every digital video file's physical size is governed by one formula: data rate multiplied by time. Add your audio track's bitrate to your video bitrate (converting both to Mbps), multiply by duration in seconds, and divide by 8 to convert megabits to megabytes. The math is universal across all containers—whether MP4, MOV, MKV, or WebM—because the file wrapper does not alter the underlying compressed stream.

Bits-Per-Pixel: the true measure of compression quality

A common mistake among video editors is assuming an 8 Mbps bitrate means the same quality across all projects. An 8 Mbps bitrate looks pristine on a 720p 24fps interview, but heavily pixelated on a 4K 60fps sports sequence. Bits-Per-Pixel (bpp) normalizes data allocation across pixel volume and temporal frequency. Aim for 0.07 to 0.10 bpp for web streaming, and 0.10 to 0.18 bpp for high-fidelity master uploads to YouTube and Vimeo.

Solving backward from upload caps

Strict upload limits are a reality of modern workflows—whether a 10 MB Discord free-tier cap, a 16 MB WhatsApp limit, or a 25 MB email attachment threshold. Instead of test-rendering repeatedly to guess the file size, the Target Size Solver inverts the formula to calculate the exact maximum video bitrate your export can afford after accounting for audio.

Delivery codecs vs. production codecs: H.264, HEVC, AV1, and ProRes

Different codecs serve fundamentally different purposes in the pipeline. H.264 remains the universal standard for compatibility. H.265 (HEVC) and VP9 halve required bitrates for equivalent fidelity, and AV1 pushes efficiency even further. Conversely, production codecs like Apple ProRes 422 compress frames independently (intra-frame) to ensure zero editing latency and maximum color grading flexibility, resulting in file sizes 4 to 6 times larger than delivery formats.

Planning storage for camera cards and live streams

Camera operators and live streamers need to know when storage will deplete before pressing record. By calculating data throughput per hour against usable card volume (reserving a 5% to 10% safety margin for filesystem overhead), you can accurately forecast your card requirements for multi-camera productions and prevent unexpected recording dropouts.

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Questions

Frequently Asked Questions

8 questions

How do I calculate video file size from bitrate?+

Add your video bitrate and audio bitrate together in Mbps, multiply by the duration in seconds, and divide by 8 to convert megabits to megabytes. For example, an 8 Mbps video with 128 kbps audio over 10 minutes equals roughly 610 MB.

What is Bits-Per-Pixel (bpp) and what is a good target?+

Bits-Per-Pixel (bpp) evaluates compression density: bpp = bitrate (in bits per second) ÷ (width × height × frame rate). Values under 0.05 bpp show visible motion artifacts, 0.07 to 0.10 bpp provides good streaming quality, and 0.10 to 0.18 bpp is the recommended target for high-definition YouTube and Vimeo uploads.

How much recording time fits on a 128 GB SD card?+

With 121.6 GB of usable space and a total bitrate of 100 Mbps, the card holds about 2 hours and 42 minutes. Data consumption is 45 GB per hour using decimal units.

What is the best bitrate for 4K YouTube uploads?+

YouTube recommends roughly 45 Mbps for 4K (2160p) SDR at 24-30fps and 68 Mbps at 48-60fps. For 4K HDR, YouTube recommends approximately 56 Mbps at 24-30fps and 85 Mbps at 48-60fps.

What bitrate should I use for OBS and Twitch streaming?+

Twitch's standard streaming guidelines recommend 6000 kbps (6 Mbps) for 1080p 60fps, and 4500 kbps for 720p 60fps or 1080p 30fps, paired with 160 kbps audio.

How much smaller is H.265 (HEVC) compared to H.264?+

At the same visual quality, H.265 typically requires about 50% less bitrate than H.264, cutting the video portion of the file roughly in half. AV1 provides an additional 30% to 50% reduction beyond H.265.

Why is Apple ProRes so much larger than H.264 or H.265?+

Apple ProRes is an intra-frame editing codec that compresses each frame independently without temporal predictive compression. This allows smooth timeline scrubbing and color grading without taxing CPU/GPU decoders, but yields files 4x to 6x larger than H.264.

Does audio bitrate make a significant difference in file size?+

Audio typically represents only 1% to 5% of total file size at standard video bitrates. However, on long recordings or when solving for strict upload limits (like a 10 MB Discord cap), a 320 kbps audio track adds over 2.3 MB per minute and can easily push an export over the limit.

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