Free Online Video Compressor

Compress Video Files Without Sacrificing Quality

Reduce video file size by 50–90% using CRF-based H.264 or H.265 encoding. Perfect for email sharing, social media uploads, reduced storage, and faster streaming — all with full quality control.

Reduce size by up to 90% CRF quality control (High/Medium/Low) H.264 & H.265/HEVC compression

Drop your file here

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Up to 100 MB free • Outputs: MP4

Select quality to see size estimate

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Files deleted in 2h

Fast processing

No signup needed

Simple & Fast

How to Use Video Compressor

Convert your files in three simple steps — no software, no signup.

Upload Your Video

Upload any video file in MP4, MKV, AVI, MOV, WebM, or other format. The compressor accepts up to 500 MB as input.

Choose Quality Level

Select High (CRF 18 — near-lossless), Medium (CRF 23 — balanced), or Low (CRF 28 — maximum compression). A size estimate updates automatically based on your selection.

Download Compressed Video

Download your compressed MP4 file. Compare the original and output sizes to see your savings before downloading.

Features

Why Use Video Compressor?

Massive Storage Savings

A 1 GB video at High quality (CRF 18) typically compresses to 200–400 MB. At Low quality (CRF 28) it can drop to 50–100 MB — up to 90% smaller.

Email & Messaging Ready

Compress videos below common email attachment limits (10–25 MB) or messaging app limits so you can share videos without cloud storage links.

Social Media Optimised

Instagram, TikTok, and Twitter have file size and bitrate limits. Our Medium quality preset produces files well within platform limits at high visual quality.

Faster Streaming

Compressed videos buffer less and stream faster over slow or mobile connections, improving viewer experience on websites and self-hosted media.

H.265 HEVC Option

Choose H.265/HEVC compression to achieve the same visual quality at roughly half the file size of H.264, ideal for 4K and high-bitrate content.

Secure & Auto-Deleted

All videos are processed in an isolated environment and automatically purged from our servers within one hour.

Compatibility

Supported Formats

All the formats you need, all in one place.

Format	Description	Extension	Best Used For
MP4 HIGH (CRF 18)	Near-lossless compression, large reduction	`.mp4`	Archiving, professional delivery
MP4 MEDIUM (CRF 23)	Balanced quality and file size	`.mp4`	Social media, YouTube, general sharing
MP4 LOW (CRF 28)	Maximum compression, smaller quality	`.mp4`	Email attachments, messaging apps
H.265 HIGH (CRF 20)	H.265 near-lossless, 50% smaller than H.264	`.mp4`	4K archiving, streaming platforms
H.265 MEDIUM (CRF 26)	Balanced H.265 quality/size	`.mp4`	Mobile streaming, bandwidth-limited delivery
RESOLUTION DOWNSCALE	Reduce 1080p to 720p for smaller output	`.mp4`	Web thumbnails, preview copies

FAQ

Frequently Asked Questions

CRF (Constant Rate Factor) is a quality-based encoding mode in H.264 and H.265. A lower CRF number means higher quality and larger file size, while a higher number means more compression and smaller files. CRF 18 = near-lossless. CRF 23 = default balanced. CRF 28 = heavily compressed.

High (CRF 18) produces files visually indistinguishable from the original for most viewers. Medium (CRF 23) is the sweet spot for sharing — good quality, significantly smaller file. Low (CRF 28) is best for situations where file size must be minimised and some visual quality trade-off is acceptable.

Results vary by source material. A 1080p MP4 at Medium quality typically compresses by 40–70%. You'll see an estimated output size shown in the interface after selecting your quality level.

H.264 has universal device support and is the safe default. H.265 (HEVC) achieves the same quality at roughly half the file size but requires newer hardware for playback. Use H.265 for archiving or 4K; use H.264 for sharing and social media.

No, by default the original resolution is preserved. If you also want to reduce resolution (e.g., 1080p → 720p), a resolution downscale option is available in the settings for additional file size savings.

Yes, but there are diminishing returns. Re-compressing an already-compressed video will produce some quality loss and may not significantly reduce file size if the source is already well-compressed. Starting from a high-bitrate or lossless source yields the best results.

Real-World Uses

Who Uses Video Compressor?

From everyday users to professionals — see how people rely on this tool every day.

Office Workers

Email Attachments

Reduce video files below 25 MB email limits so they can be sent directly as attachments without cloud storage links.

Social Media Creators

Platform Upload Limits

Compress videos to meet Instagram (4 GB), TikTok (287.6 MB), and Twitter (512 MB) upload limits while maintaining visual quality.

Storage-Conscious Users

Free Up Disk Space

Compress a video library to H.265 Medium quality and typically cut storage requirements in half with no perceptible quality difference.

Web Publishers

Faster Web Streaming

Compress background and hero videos for websites to reduce bandwidth costs and improve page load times for mobile visitors.

Videographers

Client Delivery Files

Deliver compressed web-quality copies to clients via WeTransfer or Dropbox while keeping the original high-bitrate master for yourself.

Mobile Users

WhatsApp & Messaging

Compress videos to under 16 MB for WhatsApp or under 25 MB for Telegram file sharing without quality that looks noticeably degraded.

Why TransmuteBox?

TransmuteBox vs. Alternatives

See how we compare to desktop software and other online converters.

Feature	Our Tool TransmuteBox	HandBrake	Other Online
CRF quality control			Limited
H.264 & H.265 compression			H.264 only
Resolution downscale option
File size estimate preview
No install required
Batch processing
Auto-delete after processing			Varies

Under the Hood

Technical Specifications

Built on industry-standard open-source tools for maximum quality and reliability.

Limits & Restrictions

Max input size: 500 MB (free)
Max resolution: 4K (2160p)
Output: MP4 container

FFmpeg H.264 H.265 HEVC CRF Video Compression Reduce Size

Conversion Engine

FFmpeg 6.x · libx264 · libx265 · CRF-based encoding

Output Quality

High: CRF 18 · Medium: CRF 23 · Low: CRF 28 · H.265 Medium: CRF 26

Average Speed

Multi-threaded · typical 5-min 1080p at Medium in 40–60 s

Data Security

HTTPS transfer · isolated temp dir · auto-purged in 2 h

Typical size reduction

40–80% vs original

Max resolution

4K UHD preserved

Quality presets

High · Medium · Low

Complete Guide

Video Compression Guide: CRF, Bitrate, and Getting the Best Results

Video compression is the art of making video files smaller while preserving as much visual quality as possible. Unlike audio compression, which is relatively straightforward, video compression involves sophisticated per-frame analysis. Here's what you need to know to compress video intelligently.

How Video Compression Works

Video compression algorithms exploit two types of redundancy: spatial redundancy (areas within a frame that are similar) and temporal redundancy (areas between frames that don't change). H.264 and H.265 use a combination of intra-frame (spatial) and inter-frame (temporal) prediction to compress video data by 100–1000× compared to raw video.

A key-frame (I-frame) stores complete frame data. Subsequent frames store only the differences (P-frames and B-frames). This is why video is harder to edit at arbitrary frame positions compared to audio.

CRF vs Bitrate: Which Should You Use?

There are two main approaches to controlling video file size:

CRF (Constant Rate Factor): Targets a consistent visual quality level. Bitrate adapts frame-by-frame — complex scenes use more data, simple scenes use less. Best for archiving and general compression when quality matters most.
Target Bitrate (ABR/VBR): Targets a specific average bitrate regardless of scene complexity. Better when you need to hit a specific file size or network delivery constraint.

For most users compressing personal videos, CRF is the right tool — it automatically allocates bits where they're needed most.

H.265 vs H.264: The Compression Efficiency Comparison

H.265 (HEVC) provides approximately 40–50% better compression than H.264 at the same visual quality. In practice:

A 500 MB MP4/H.264 file → ~250 MB as H.265 at the same quality.
A 4K 1-hour recording of ~50 GB raw → ~4 GB H.265 at high quality.

The trade-off: H.265 encoding takes 2–3× longer and H.265 playback requires hardware support (all post-2015 devices have this). For archiving and 4K, H.265 is almost always the better choice.

Common Compression Mistakes to Avoid

Over-compressing already-compressed video: Each re-encode compounds quality loss. Compress only once from the highest-quality source you have.
Using the wrong preset: CRF 28 for archival or CRF 18 for social media are both wrong choices. Match the preset to your use case.
Ignoring resolution: Compressing a 4K video to Medium quality still produces a large file. Consider also downscaling to 1080p if 4K resolution isn't needed by the recipient.
Forgetting audio: Audio rarely needs to be higher than 192 kbps AAC. Including a high-bitrate audio track on a heavily compressed video wastes space.

Target File Sizes for Common Platforms

Use these targets when compressing video for specific delivery platforms:

WhatsApp: Under 16 MB — use Low quality (CRF 28) at 720p.
Email: Under 25 MB — use Low quality at 480p or 720p.
TikTok: Under 287 MB — Medium quality (CRF 23) at 1080p is fine.
YouTube: No practical limit for upload — use High quality (CRF 18) at original resolution.
Slack/Teams: Under 50 MB — Medium quality at 720p.

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