Compression knowledge
File compression guides
Practical answers about shrinking files — then open the matching Image, PDF, Video, or Audio compressor. Everything runs in your browser.
File compression shrinks how many bytes a file uses by removing redundancy or discarding detail. Lossless methods pack data so you can restore the original; lossy methods throw away information to get smaller delivery files.
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Lossless compression shrinks files without throwing away information — you can restore the exact original. Lossy compression removes detail humans are less likely to notice so files get much smaller for photos, video, and music.
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Image compressors decode pixels, then re-encode with a codec. JPEG and lossy WebP discard fine detail for smaller photos; PNG and lossless WebP pack pixels more efficiently without throwing detail away — but often stay larger.
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Video compression re-encodes frames with a codec (often H.264 in MP4). Lower quality or bitrate settings discard more detail and motion precision so uploads and shares fit size limits.
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Audio compressors re-encode sound at a target bitrate. MP3 and AAC remove quiet or masked detail so podcasts and music shares stay small; WAV and FLAC keep lossless masters that stay large.
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Compressed files lose quality when the encode is lossy — the algorithm permanently discards information to save bytes. You see softness, banding, or muffling; you cannot recover the discarded detail from the small file alone.
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Resize oversized dimensions first, then use a moderate quality encode (or lossless when files stay reasonable). Avoid repeated lossy saves and keep a master for future edits.
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Most bulky PDFs are image-heavy scans. Re-encoding page imagery at a lower JPEG quality shrinks them. Text-heavy vector PDFs shrink less — and aggressive compression can make text non-selectable.
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Bitrate is how many bits per second a media encode uses. Higher bitrate ≈ larger files and usually better quality; lower bitrate ≈ smaller files and more risk of artifacts.
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Compress with Format Convertly
Open a category hub, then pick a format tool such as JPG, PNG, MP4, or MP3.
Shrink photos and graphics in your browser — format-specific tools for JPG, PNG, WebP, HEIC, and AVIF.
Shrink large PDFs locally with a quality slider before email or upload.
Re-encode common video containers to a smaller MP4 in your browser.
Re-encode audio to a smaller MP3 — podcasts, voice notes, and music shares.