Key takeaways
- Lossy formats such as MP3 and JPG are small but lose some detail.
- Lossless formats such as WAV, FLAC and PNG keep all the detail but take more space.
- Convert from a high-quality original, never from a low-quality copy.
The short answer
A file format is the way information is stored. Choosing the right one affects the quality, the size and what devices can open the file. This guide explains the formats you meet most often, with simple advice for each kind of file.
Audio formats
| Format | Type | Best for |
|---|---|---|
| WAV | Uncompressed, large | Recording, mixing and masters. Roughly 10 MB per minute at CD quality. |
| FLAC | Lossless compressed | Keeping full quality while saving space |
| MP3 | Lossy compressed | Sharing and playing everywhere. A 128 kbps file is about 1 MB per minute, and 320 kbps about 2.4 MB per minute. |
| AAC | Lossy compressed | Streaming and many phones |
| AIFF | Uncompressed | Apple’s equivalent of WAV |
Never convert an MP3 back to WAV and expect better quality. The detail that was removed does not return. Send WAV files to mixing engineers. See prepare your song for mixing.
Image formats
| Format | Best for | Notes |
|---|---|---|
| JPG | Photographs | Small, but repeated saving lowers quality |
| PNG | Logos, screenshots and images with transparency | Lossless but larger |
| WebP | Websites | Usually smaller than JPG or PNG at similar quality. See compress and resize images. |
| GIF | Simple animations | Limited colours |
| SVG | Logos and icons | Scales to any size without blurring |
| HEIC | iPhone photos | Efficient, but not every device opens it, so convert when sharing |
Video formats
- MP4: the most widely supported format for sharing and uploading.
- MOV: common on Apple devices and used in editing.
- MKV: flexible, often used for downloads and long videos.
- Higher resolution and frame rate mean larger files. See video editing on a phone for export settings.
Document formats
| Format | Best for |
|---|---|
| Sharing documents that must look the same everywhere | |
| DOCX | Editable documents in Word |
| TXT | Plain text with no formatting |
| CSV | Simple tables that open in spreadsheets. See spreadsheet basics. |
| XLSX | Spreadsheets with formulas |
Choosing the right format
- Ask what the file is for: sharing, editing, printing or archiving.
- Keep an original in the highest quality you have.
- Make smaller copies for email and websites.
- Check what the receiver can open.
- Name files clearly, with a version number or date.
Converting safely
- Use trusted software or websites, and avoid unknown apps. See fake apps and malware.
- Do not upload private or unreleased files to free online converters.
- Keep the original until you have checked the converted copy.
- Remember that file size affects mobile data. See saving mobile data.
Quick checklist
- Keep high-quality originals
- Use WAV or FLAC for masters and MP3 or AAC for sharing
- Use JPG for photos and PNG for logos
- Use PDF for fixed documents
- Convert from originals, not copies
- Protect private files
Key points to remember
Formats are tools. Once you know what each is good at, you can keep quality where it matters and save space where it does not. For managing the files themselves, read recover deleted files and photos.
This guide is general information to help you decide and act with confidence. Features, prices and settings change, so confirm current details with your device maker or service provider before you act. Last reviewed October 2026. Read our editorial standards.
