Search-intent guides
Guides
One page per intent — what a format is, which format to pick, how to open a file, and how to fix common problems. Format vs format lives on Compare; conversions live under Converters. Compare; Converters.
Entity guides for each format
Decision guides by job
Compatibility on Windows, Mac, phone
Troubleshooting long-tail fixes
Best format for…
Decision intent — pick a format for a job, then convert.
For modern websites, WebP or AVIF usually win on size. Keep JPG for maximum compatibility, PNG for UI/transparency, and SVG for logos that must scale.
JPG remains the universal photo share format. HEIC saves space on iPhones. WebP/AVIF are better for websites. PNG is usually the wrong photo delivery format.
SVG is the best logo format for the web. PNG is the best raster fallback with transparency. Avoid JPG for logos — it blurs edges and cannot do transparent backgrounds.
PNG and WebP (and AVIF) support transparency. JPG and most HEIC share paths do not. SVG can also be transparent for logos.
Use JPG/WebP/AVIF for lifestyle photos, PNG/WebP for cutouts with transparency, and SVG for brand marks. Optimize for PDPs and category grids.
JPG and PNG are the safest email image formats. Avoid relying on SVG or HEIC. Animated GIF still works for simple motion; MP4 support in email is uneven.
TIFF and high-quality PDF pipelines dominate professional print. PNG works for sharp graphics; JPG is acceptable for photos at high quality. WebP/AVIF are web formats — convert before print.
JPG is the safest social photo upload. PNG for graphics with text or transparency. Convert HEIC before posting from desktop tools. Platforms often recompress everything anyway.
AVIF and WebP usually beat JPG for photos. Lossless WebP often beats PNG for simple graphics. SVG wins for simple logos. Compress smartly — do not just switch formats blindly.
For masters, prefer TIFF/PNG/lossless pipelines (or HEIC/AVIF carefully). For delivery, high-quality JPG/WebP/AVIF can look excellent — lossless is not always required for human viewing.
MP4 (H.264/AAC) is the safest website video format. WebM is excellent for open/controlled stacks. Convert MOV/AVI uploads to MP4 before embedding.
MP4 is the social video default. Convert MOV/MKV/AVI/WebM to MP4 for schedulers and ads managers.
MP4 with H.264/AAC is the compatibility king. Use it when sending to clients, smart TVs, and mixed devices.
Efficient codecs in MP4/WebM beat ancient AVI/MOV ProRes for delivery size. Resolution and bitrate matter as much as the container.
Edit in WAV (or high-quality AAC). Deliver MP3 for maximum podcast-app compatibility; M4A/AAC is excellent for modern feeds.
FLAC/ALAC for lossless libraries; WAV for studio bounces; MP3/AAC for everyday listening and sharing.
M4A/AAC and Opus are excellent for speech. MP3 remains the share default. WAV for editing.
Opus/AAC beat MP3 at low bitrates; MP3 still wins raw compatibility. Never use WAV/FLAC for tiny chat clips.
WAV/AIFF for production PCM; FLAC/ALAC for lossless libraries; high-bitrate AAC/MP3 only for delivery.
PDF for final shared reads and signatures. DOCX when people must edit. Avoid relying on ODT/DOC/RTF unless you know the audience.
DOCX is the default editable business format. ODT for open suites. Convert PDF to Word only when a text layer exists — scans need OCR.
PDF is the print handoff standard. Export from DOCX/PPTX when layout is final.
CSV for values and pipelines. XLSX when humans need sheets, formulas, and formatting. TSV when commas fight your data.
JSON is the default API payload. XML when standards require it. YAML/TOML for human-edited config — convert to JSON for strict APIs.
ZIP is the best everyday folder share. 7Z/RAR compress more for technical audiences. TAR.GZ for Unix/source workflows.
WOFF2 is the best default for websites. Keep WOFF as a legacy fallback. Use TTF/OTF for design and desktop installs — convert to WOFF2 before shipping to the browser.
How to open…
Open unfamiliar files on desktop or mobile, then convert if needed.
HEIC opens natively on iPhone and Mac. On Windows and Android, install a HEIF viewer or convert to JPG — the fastest fix for sharing and uploads.
Modern browsers open WebP fine. Older Windows viewers, printers, and some CMS tools still want JPG or PNG — convert when compatibility matters more than file size.
AVIF is tiny and sharp, but support is still catching up outside modern browsers. Convert to JPG or WebP when a device or CMS blocks AVIF.
MKV is a flexible container, not a codec. VLC plays almost every MKV. For Apple devices, TVs, and upload forms that demand MP4, convert MKV → MP4.
EPUB opens in Apple Books, Calibre, and most e-reader apps. On Windows without a reader, install one — or convert EPUB → PDF for a familiar page layout.
ODT is LibreOffice/OpenOffice’s document format. Word can import many ODTs, but formatting can shift — convert ODT → DOCX when colleagues live in Microsoft Word.
7Z needs 7-Zip or a compatible archiver. Windows Explorer and macOS Archive Utility often fail. Install 7-Zip (Windows) or Keka/The Unarchiver (Mac) — or ask the sender for ZIP.
Install Microsoft HEIF/HEVC extensions, or convert HEIC → JPG once. Conversion is faster when you need email, Slack, or website uploads to just work.
Newer Android and Google Photos often open HEIC. Older devices may not — convert to JPG before sideloading from a PC or chat app.
Browsers open WebP. Windows Photos support varies by build. For Paint, printers, and older Office workflows, convert WEBP → JPG or PNG.
QuickTime often refuses MKV. Use VLC/IINA, or convert MKV → MP4 (or MOV) for Apple-native playback and editing.
Use Calibre, Edge (where supported), or another reader — or convert EPUB → PDF if you want a familiar document window.
Why won’t…
Fix common file problems, then convert to a friendlier format.
Won't open
HEIC is Apple’s efficient photo format. Many Windows PCs, older Android apps, email clients, and websites only accept JPG/PNG — so the file isn’t broken, the destination lacks a HEIC decoder.
MOV is a QuickTime-friendly container. Windows and many web uploads prefer MP4. Convert MOV → MP4 for playback and sharing.
AVIF is efficient but still unevenly supported outside modern Chrome/Firefox. Convert AVIF → JPG or PNG for universal sharing while keeping AVIF for the web.
File too large
PNG is lossless and stores every pixel. Photos saved as PNG stay huge. Use JPG or WebP for photos; keep PNG for UI, logos, and transparency.
Long duration, high resolution, and high bitrate drive size. Convert to MP4 if needed, then re-encode with a video compressor — remuxing alone rarely shrinks much.
Scans and embedded images dominate PDF weight. Compress pages, remove extras, and keep a master with selectable text when you need it.
WAV is usually uncompressed PCM. Convert to MP3 (or M4A) for sharing; keep WAV/FLAC as the archive master.
TIFF often stores uncompressed or lightly compressed print masters. Convert to JPG/WebP for sharing, or PDF for multi-page delivery — keep TIFF for archival print work.
BMP is typically uncompressed raster data. Convert BMP → PNG for screenshots/UI or JPG for photos — size drops dramatically with no practical downside for sharing.
GIF is an old 256-color animation format with weak compression for long clips. Prefer MP4/WebM for motion, or shorten/resize the GIF.
PDF can embed images with little extra compression — or re-encode poorly. Resize images first, then JPG/PNG → PDF, and use a PDF compressor for email limits.
Quality issues
MP3 is lossy. Converting WAV/FLAC → MP3 discards detail on purpose. MP3 → MP3 again stacks generational loss. Convert once from a master at a sensible bitrate.
True SVG stays sharp when it’s real vectors. Blur usually means the “SVG” embeds a raster image, was exported tiny, or you’re viewing a rasterized PNG/JPG stand-in.
JPG is lossy and can’t store transparency. Softness and checkerboard flattening are expected. Use higher JPG quality or keep PNG/WebP for sharp UI.
GIF is limited to ~256 colors and often lower frame rates. Short clips at smaller size look better; for quality motion, keep MP4 instead of forcing GIF.
PDF→image sharpness depends on render DPI/resolution. Low export resolution looks blurry; raise output size, or keep PDF/SVG for vector text when possible.
HEIC often carries Display P3 / HDR-ish phone color. JPG on sRGB screens can look less vivid after conversion. Convert carefully and preview on the target device.
Compatibility
Scanned PDFs are pictures of pages. Without OCR, there’s no text to search or copy. Add a searchable text layer or convert via OCR to Word/TXT.
Many upload pipelines still whitelist only JPG/PNG. The WebP isn’t invalid — the server validation is old. Convert WebP → JPG or PNG for that channel.
Many PDFs are fixed layouts or scans. Convert PDF → Word for text edits when the PDF has a text layer; use OCR when it’s only images.
Sites need web font formats (usually WOFF2). Convert TTF/OTF → WOFF2 and serve with correct CSS @font-face rules and licensing.
MKV is a flexible container many phones don’t handle in stock apps. Convert MKV → MP4 (H.264/AAC when possible) for reliable mobile playback.
WebM is common on the web but historically weak on iPhone. Convert WebM → MP4 for AirDrop, camera roll, and most editors.
FLAC is lossless and widely supported on desktop, but mobile/auto ecosystems often prefer AAC/MP3. Convert FLAC → MP3 or M4A for phones, keep FLAC as the archive.
Conversion surprises
JPG already discarded detail. PNG stores the remaining pixels losslessly — often using more bytes. Size goes up; sharpness beyond the JPG does not come back.
PDF freezes a layout using available fonts and page metrics. Missing fonts, different printers, or complex objects cause drift. Embed fonts and review before sending.
CSV is plain delimited text — one grid, no formulas, no formatting, typically one sheet. Flatten values first and export the sheet you need.
If fonts aren’t available at convert time, PDF substitutes. Use standard fonts or embed/outline critical text before converting PPT → PDF.
CSV is plain text — Excel guesses separators and types. Prefer XLSX for Excel work, or import CSV with explicit delimiter/UTF-8 settings.
What is…
Learn what each format is, then jump to a converter.