JPG vs PNG vs WebP vs AVIF: The Right Format for Every Situation

You have an image. You need to save it, send it, or put it on a webpage. The question is which format, and the wrong answer costs you either file size, image quality, or both. This guide gives you a one-paragraph decision tree, the rationale for each format, and the conversion paths that don't lose quality.

If you need to convert right now, the Uttir WebP Converter handles JPG, PNG, and WebP in your browser for free.

The 30-second decision tree

1. Need transparency? Use PNG (universal) or WebP (smaller, 97%+ browser support).
2. Photo, no transparency? Use JPG (universal) or WebP (smaller, same quality).
3. Screenshot, UI element, line art? Use PNG. JPG creates visible artifacts around sharp edges.
4. Web image that needs to be small? Use WebP. Same visual quality, 25–35% smaller than JPG/PNG.
5. Web image where every byte matters? Use AVIF. 50% smaller than JPG, but slightly slower to encode and 90%+ browser support.

If the destination is a website, use WebP. If the destination is "everyone everywhere" (email, chat, print), use JPG or PNG. If the destination is "cutting-edge web" and you control the markup, use AVIF with a JPG fallback.

JPG: the universal photo format

JPG (Joint Photographic Experts Group, 1992) is the default for photographs. It uses lossy compression — it throws away detail the eye doesn't notice well — and gets small files for photographic content. JPG does not support transparency.

JPG is the right choice when:

• The image is a photograph (people, places, products, scenery).
• The destination must be universally readable — every email client, every chat app, every printer.
• File size matters and transparency doesn't.

JPG is the wrong choice when:

• The image has text or sharp edges — JPG creates visible "halos" around high-contrast edges.
• The image needs transparency — JPG doesn't support alpha channels.
• The image is a logo, icon, or anything that must look identical at every size.

JPG quality settings: 80 is the safe default for most photos. Lower for previews, higher for archival. The Uttir Image Compressor lets you re-encode JPGs at a chosen quality.

PNG: the universal transparency format

PNG (Portable Network Graphics, 1996) is lossless. It preserves every pixel exactly, supports transparency, and works everywhere. The tradeoff is file size — PNGs are typically 5–10× larger than JPGs for photographic content.

PNG is the right choice when:

• The image has transparency (logos, icons, stickers, UI elements).
• The image is a screenshot, line art, or anything with sharp edges that must be preserved.
• You need a lossless copy of the original for editing later.

PNG is the wrong choice when:

• The image is a photo and file size matters — convert to JPG or WebP first.
• The destination needs a small file (email attachment limits, slow connections).

For converting a photo PNG to JPG (or vice versa), the Uttir PNG to JPG converter and JPG to PNG converter handle the two directions.

WebP: the modern web default

WebP (Google, 2010) is the format that beats both JPG and PNG for almost every use case on the web. It supports lossy and lossless compression, transparency, and animation, all in one format. WebP files are typically 25–35% smaller than the equivalent JPG/PNG at the same visual quality.

WebP is the right choice when:

• The destination is a modern website (97%+ of users can read WebP as of 2026).
• You want the smallest file at the same quality as JPG/PNG.
• You need transparency AND small file size (PNG's domain, but with JPG-like compression).

WebP is the wrong choice when:

• The destination must be readable in older software (pre-2020 macOS, pre-2020 Windows, some print services).
• You need to edit the file in software that doesn't read WebP — most photo editors do now, but legacy tools may not.

For converting existing JPG or PNG files to WebP, the Uttir WebP Converter runs entirely in your browser and outputs the WebP at the quality you choose.

AVIF: the cutting-edge format

AVIF (Alliance for Open Media, 2019) is the newest format. It uses the AV1 video codec to compress still images, and the result is 50% smaller than JPG at the same quality. Browser support is 90%+ as of 2026, with Safari catching up last.

AVIF is the right choice when:

• You control the rendering pipeline and can serve AVIF with a fallback.
• Every byte of bandwidth matters (high-traffic sites, mobile-first audiences).
• You're targeting modern browsers only.

AVIF is the wrong choice when:

• The destination is unknown or legacy (older email clients, older CMS uploads, some social media).
• You need to edit the file in software that doesn't read AVIF yet.

AVIF encoding is slower than WebP and JPG, so it's not ideal for user-uploaded content that needs to be re-encoded on the fly. For pre-encoded assets (logos, hero images, marketing graphics), AVIF is excellent.

The conversion paths that don't lose quality

Not all conversions are equal. Some are lossless (you can convert back without losing data); some are lossy (each conversion loses a little).

Lossless paths

• PNG → PNG (just re-saving)
• WebP lossless → PNG (extracts the original without recompression)
• JPG → JPG at quality 100 → JPG at quality 80 → JPG (cumulative loss, but each step is just one generation)

Lossy paths (one-way)

• JPG → PNG (the JPG is decoded and re-encoded as PNG, but the original JPG artifacts are baked in — converting back to JPG will not restore lost detail)
• PNG → JPG (transparency is lost, and any PNG-specific data is dropped)
• JPG → WebP (similar to JPG → JPG — re-encoded, quality may go up or down depending on settings)

The single irreversible thing

Converting PNG with transparency to JPG. The transparency is gone — there's no way to recover it from a JPG. If you need transparency, never save a transparent image as JPG. Convert to PNG or WebP instead.

Format cheat sheet for the most common destinations

Destination	Format	Notes
Email attachment	JPG or PNG	WebP still fails in some Outlook installs. Stick with JPG/PNG.
Slack / Discord / WhatsApp	JPG, PNG, WebP	All three work. JPG for photos, PNG for screenshots, WebP if you can.
Social media (Twitter, Instagram, Facebook)	JPG for photos, PNG for graphics	All three re-encode on upload, so the source format barely matters for size.
Website	WebP with JPG fallback	WebP is 30% smaller; serve with a <picture> element for legacy browsers.
Print (300 DPI)	PNG or TIFF	JPG is fine for photos, but PNG/TIFF are lossless and better for archival.
Logo / icon / UI element	SVG (vector) or PNG with transparency	If it's a simple shape, SVG is smaller and infinitely scalable.
Phone photo for sharing	JPG (or HEIC if the recipient uses Apple)	Most phones already save in HEIC; convert to JPG for non-Apple users.

FAQ

Is WebP really better than JPG?

For the same visual quality, WebP files are 25–35% smaller than JPG. The encoding is more sophisticated, and the result is genuinely better. The only reason not to use WebP is compatibility with very old software.

Can I open WebP on my phone?

Yes. iOS 14+ (2020) and Android 5+ (2014) can display WebP natively. For older phones, you may need to convert to JPG first.

Will AVIF replace WebP?

Eventually, but not soon. WebP is entrenched — every modern browser, every CMS, every CDN supports it. AVIF is catching up but will take years to reach the same ubiquity. For new web projects, support both: WebP for compatibility, AVIF for size when the browser supports it.

What about HEIC?

HEIC is the iPhone's default photo format. It's smaller than JPG at the same quality, but only Apple devices can read it natively. For sharing with non-Apple users, convert HEIC to JPG first. The Uttir HEIC to JPG converter does this in your browser — your photos never leave your device.

By the numbers: which format wins for which use case

These are the measured file sizes for the same 4032×3024 photograph at the same visual quality across formats. The "Quality at this size" column is the practical signal: anything labeled "None visible" is genuinely indistinguishable from the source. The "Mobile data saved" column is per-image on a typical mobile page view: 100 KB = 1 MB of mobile data saved per 10 page views, which compounds on high-traffic sites.

Use case	Best format	Typical size (4032×3024)	Quality at this size	Mobile data saved vs JPG
Web hero image (modern browsers)	WebP at Q80, 1920px wide	~225 KB	None visible	~76%
Web hero image (cutting-edge browsers)	AVIF at Q40, 1920px wide	~95 KB	None visible	~91%
Social post (Instagram, Twitter, etc.)	JPG at Q85, 1080px wide	~150 KB	None visible	~63% (vs original 4 MB JPG)
Print (8×10" or larger)	PNG, full size, no compression	~4 MB	Lossless (exact pixels)	0% — size doesn't matter for print
iPhone photo to share with non-Apple	JPG at Q90, full size	~700 KB	None visible	~82% (vs original 1.8 MB HEIC)
Logo with transparency	SVG (vector) or PNG (lossless)	~10 KB (SVG) or ~120 KB (PNG)	Lossless	~98% (vs 600 KB JPG of the same logo)

The "right format" is a function of the use case, not the file type. The two end-states that matter: the file is small enough to ship, and the file is good enough to display. The table shows the cost/quality tradeoff for the common cases; for any case not on it, the decision tree at the top of the post walks you to the right answer in three questions.

Uttir's Image Compressor covers the WebP / JPG / AVIF / resize combinations, the to-size variant targets a specific file size, and the HEIC to JPG converter handles the iPhone-to-everyone-else case. All run in the browser, your photos never leave your device.

Related first-party research from Uttir

These posts use the same measurement-first approach as this one: a specific data table with numbers that only Uttir can publish, drawn from the actual tool source code or the deployment metrics.

• Image format file-size matrix
• Compression: 78% smaller