How to Convert File Formats: The Complete Guide (Images, PDFs, Docs, Audio, Video)

JPG vs PNG vs WebP. PDF vs DOCX. CSV vs XLSX. MP4 vs MOV. People search "how to convert X to Y" millions of times every month because file format compatibility is genuinely confusing, and getting it wrong means rejected uploads, blurry images, broken documents, or files that won't open.

This guide explains what each common format is for, when to convert between them, and which conversions are safe versus which ones destroy quality. By the end you'll know the right format for any situation, plus how to convert in your browser without uploading anything.

The two big categories: lossy vs lossless

Before any specific format, understand this one concept, it's the difference between "looks identical to the original" and "looks the same most of the time."

Lossless formats preserve every bit of the original. Saving a lossless file 100 times produces a file identical to the first save. Examples: PNG, GIF, TIFF, WAV, FLAC, ZIP.

Lossy formats throw away data the algorithm thinks you won't notice, to make the file smaller. Saving a lossy file repeatedly degrades it slightly each time (generational loss). Examples: JPG, WebP (lossy mode), MP3, AAC, MP4 video.

For documents and source files: use lossless. For final-output sharing where size matters: use lossy. Never re-save a lossy file as a lossy file if you can avoid it, go back to the original.

Image formats: when to use what

JPG (or JPEG)

The format of photographs. Lossy, small files, no transparency support. Use for: photos, social media images, anything where the file is going to be looked at once and discarded.

Don't use for: logos, screenshots, illustrations with hard edges (text gets fuzzy artifacts around it), any image you'll re-edit multiple times.

PNG

The format of screenshots and graphics. Lossless, larger files than JPG, supports transparency. Use for: logos, icons, screenshots, anything with text or sharp edges, any image that needs a transparent background.

Don't use for: photographs you're publishing to web (file is 3-5x larger than JPG with no visible quality benefit).

WebP

The modern format that combines the best of both. Lossy and lossless modes, transparency support, 25-50% smaller than JPG at the same visual quality. Use for: web images, where you can serve different formats to different browsers.

Compatibility note: WebP is supported by all modern browsers (Chrome, Firefox, Safari 14+, Edge), but some older apps and certain enterprise software still don't accept it. When uploading to a system that rejects WebP, convert it to JPG or PNG first.

GIF

Animated images. Outdated for everything except short loops. For static images use PNG. For better-quality animation use MP4 or WebM.

SVG

Scalable vector graphics. Not really a "format" in the same sense, it's XML that describes shapes. Use for: logos, icons, illustrations with no photographic detail. Scales perfectly to any size. Tiny file sizes.

Common image conversions and when each makes sense

• PNG → WebP, for web use, cut file size by half. Convert here.
• PNG → JPG, when you need smaller files and don't have transparency. Quality hit is small for photos, noticeable for screenshots.
• JPG → PNG, only useful if you've already added a transparent background somehow (e.g., after removing background) and need to preserve transparency. Convert here.
• HEIC → JPG, iPhone photos in HEIC format don't open in older Windows or non-Apple apps. Conversion to JPG fixes compatibility.
• WebP → JPG, for systems that reject WebP. Convert here.
• Any → PDF, for combining images into a single document. Convert here.

Document formats: the PDF and Word ecosystem

PDF

The universal "this is what the document looks like, finalized" format. Cross-platform, preserves layout exactly, supports text, images, forms, signatures, and encryption.

Use PDF for: finalized documents going to others (contracts, invoices, reports, forms to fill in), anything that needs to look identical on every device, anything you're publishing or printing.

Don't use PDF for: documents you're still editing (PDFs are hard to edit). For editing, use DOCX and export to PDF when done.

Common PDF operations: merge, split, compress, protect with password, sign.

DOCX

Microsoft Word document. Editable. Used for collaboration, drafts, anything that's being worked on. Compatible with Word, Google Docs, LibreOffice, Pages.

Convert DOCX → PDF when sharing a finalized version. Convert PDF → DOCX only when you need to edit and don't have the original (lossy in terms of layout, formatting can break).

TXT

Plain text, no formatting. Use for: notes, code snippets, anything where formatting doesn't matter. Always opens in any app. The lowest common denominator.

RTF

Rich Text Format. Halfway between TXT and DOCX. Mostly legacy. Use when sending formatted text to someone whose software you don't know.

Spreadsheet formats

XLSX

Microsoft Excel format. The standard for spreadsheets. Supports formulas, formatting, multiple sheets, charts.

CSV

Comma-Separated Values. Plain text. Each row is a line, columns separated by commas. No formulas, no formatting, no merged cells. Use for: data exchange between systems, importing into databases, exporting from one tool to another.

Convert XLSX → CSV when you're exporting data for another program to read. You lose formulas and formatting, only the values remain.

Convert CSV → XLSX when you want to add formatting, formulas, or charts to raw data.

TSV

Tab-Separated Values. Same idea as CSV, but tab characters separate columns instead of commas. Useful when your data contains commas (which would break CSV parsing).

Video and audio formats

MP4

The universal video format in 2026. Plays everywhere. Use for any video you're sharing or uploading.

MOV

Apple's QuickTime format. Common from iPhone recordings and Mac apps. Many Windows applications don't play MOV natively, convert to MP4 for compatibility.

WebM

Web-optimized video. Smaller than MP4 at similar quality. Used by YouTube internally. Some platforms still don't accept it for upload, use MP4 if unsure.

MP3

The universal audio format. Lossy, small files, plays everywhere.

WAV

Uncompressed audio. Huge files, perfect quality. Use as source format for editing; export to MP3 for sharing.

FLAC

Lossless compressed audio. Audiophile-grade. Smaller than WAV, perfect quality. Most consumer apps support it; some don't.

Archive formats

ZIP

Universal compressed archive. Every operating system can open it. Use for: bundling multiple files for email or download.

RAR

Older proprietary format. Often used by software pirates (which is why some email systems block it). Use ZIP unless you specifically need RAR.

7Z

Newer, better compression than ZIP. Requires 7-Zip or similar app to open. Use only when you need maximum compression and you know the recipient has 7-Zip.

TAR.GZ

Standard on Linux. Common for distributing software source code. Most users won't encounter this.

The conversions that destroy quality (avoid)

• JPG → JPG (re-save), every save loses quality. Edit from the original, save once at the end.
• Compressed video → re-encoded video, same issue, generational loss. Edit from highest-quality source.
• PDF → DOCX → PDF, layout breaks twice. Edit the DOCX original if you have it.
• PNG → JPG → PNG, once you've gone lossy, going back to lossless doesn't recover the data.
• WebP (lossy) → PNG, file gets larger but quality doesn't improve. The damage is already done.

The rule: always keep the highest-quality original. Convert from the original to whatever final format you need, never from a derivative.

How to convert files free in your browser

For all the common image and PDF conversions, our tools page has dedicated converters that run entirely in your browser. The advantages over generic "online converter" sites:

• No upload, your files stay on your computer
• No file size limits, process whatever your browser can handle (typically up to 1-2 GB depending on RAM)
• No watermark on output
• No queue, instant processing
• No signup

Most conversions are one click: drop the file, pick the output format, download.

Common questions

What's the best format for web images?

WebP if your audience uses modern browsers (99% of internet users in 2026). JPG as a fallback for photos, PNG for screenshots and graphics with transparency. Modern websites serve WebP with JPG/PNG fallback automatically via the <picture> element.

What's the best format for printing?

PDF for documents. For images going to a print shop: TIFF (lossless, full color depth) at 300 DPI. PNG also works at 300 DPI for digital prints. Don't send JPG to professional printers unless they specifically request it.

Can I convert files on my phone?

Yes, all browser-based converters work on mobile. The Files app on iOS and the Downloads folder on Android can both receive converted files. Just open the converter in Safari or Chrome and use the same drag-and-drop interface (or "select file" picker on mobile).

Do conversions reduce quality?

Lossless → lossless: no quality change. Lossless → lossy: quality reduction (visible at high compression, invisible at moderate). Lossy → lossless: file gets bigger but quality doesn't improve. Lossy → lossy: quality reduction every time. The rule: convert once, from the highest-quality original.

How do I know what format a file actually is?

The extension can lie, someone can rename a file from .docx to .pdf and it won't actually open as a PDF. To check the real format, you can right-click and look at file info on most operating systems, or upload to any reputable file identifier tool. On Linux, the file command tells you the actual format regardless of extension.

The bottom line

For images: use JPG for photos, PNG for graphics, WebP for web. For documents: PDF for final, DOCX for editing. For data: CSV for exchange, XLSX for analysis. Convert once from the highest-quality original to the final format you need. Use browser-based converters so your files stay private. Save the bookmark.

Browse free file conversion tools →