You switch your WordPress site to AVIF for the smaller files and faster scores, and it looks great, until a visitor on an older iPhone sends a screenshot of broken image icons where your photos should be. The format is not the villain here. A missing fallback is.
AVIF and WebP both shrink images far below JPEG, and both are widely supported in 2026. The confusion, and the occasional broken image on Safari, comes from how you deliver them, not which one you pick. Here is how the two formats actually compare today, why the “iOS Safari break” happens, and how to set up either one in WordPress so it breaks for nobody.
The short version
WebP is effectively universal now, supported by more than 97 percent of browsers including Safari since 2020, so it works with no fallback needed. AVIF is a bit newer, supported by around 95 percent including Safari 16.4 and up, and it produces even smaller files. The broken images on older iPhones happen only when a site serves AVIF with no fallback for the small share of devices that cannot read it. The fix is simple: never serve a single next-gen format alone. Use a fallback chain, and either format is safe.
Table of Contents
A quick primer on the two formats
Both AVIF and WebP are modern image formats built to be much smaller than JPEG or PNG at the same quality. WebP is the older of the two, well established and boringly reliable. AVIF is newer and generally compresses better, especially for photographs, where it can be meaningfully smaller than WebP at similar quality. For a photo-heavy page, AVIF’s savings can run 40 percent or more below a baseline JPEG, with WebP a step behind. In short: WebP is the safe workhorse, AVIF is the newer, leaner option.
The 2026 support picture
This is where the fear comes from, and it is mostly outdated. According to browser support data, WebP now works in over 97 percent of browsers, having been supported in Safari since version 14 in 2020, so it needs no fallback at all. AVIF has caught up fast, reaching around 95 percent, with support in Safari 16.4 and later, which covers the large majority of active iPhones. The gap is the small remainder on older iOS versions, and that gap is the entire source of the “AVIF breaks on Safari” reputation.
Where the Safari break actually comes from
Here is the real cause, and it is not AVIF’s fault. If you serve an AVIF image directly, with no alternative, then any device too old to decode AVIF, such as an iPhone stuck on an older iOS, has nothing to show and renders a broken image. That is not the format failing; it is the delivery skipping a safety net. WebP rarely shows this because almost nothing modern lacks WebP support. AVIF shows it only when a site treats a 95-percent format as if it were 100 percent and forgets the other five.
The fix: never serve one format alone
The reliable pattern is to offer the browser a choice and let it take the best format it understands. In HTML that is the picture element: you provide an AVIF source, optionally a WebP source, and a standard JPEG as the final fallback, and the browser silently picks the first one it can read. A visitor on a current phone gets tiny AVIF, an older one quietly falls back to WebP or JPEG, and nobody sees a broken image. Done this way, AVIF-first delivery is safe for everyone, and the choice of format stops being a risk.
How to set it up in WordPress
You rarely need to hand-write that markup, because WordPress and its plugins handle it. WordPress core has supported WebP since version 6.1 and added AVIF in 6.5, so the platform can generate these formats natively. For automatic delivery with fallbacks, image plugins like ShortPixel, Imagify, EWWW, or Converter for Media will create the next-gen versions and serve them with the right fallback, no coding required. Alternatively, a CDN or a service like Cloudflare can negotiate the format per request based on what the browser advertises it supports, delivering AVIF or WebP automatically. Either route gives you the savings without the breakage.
So which should you use?
If you want the simplest, zero-risk setup, WebP is the safe default, because its near-universal support means it works even served alone. If you want the best performance and smallest files, use AVIF, but only with a proper fallback through the picture element or a plugin or CDN that negotiates formats. The honest verdict is that this is not really AVIF versus WebP. It is single-format versus fallback. Pick AVIF for the savings, keep WebP or JPEG behind it as the safety net, and you get speed with no broken images.
Frequently asked questions
Is AVIF or WebP better for WordPress?
AVIF usually produces smaller files, especially for photos, while WebP has slightly wider support and works even without a fallback. For most sites, AVIF served with a fallback gives the best performance, but WebP alone is the simplest safe choice.
Why do AVIF images break on Safari?
Only on older Safari and iOS versions that predate AVIF support, and only when the image is served with no fallback. Safari 16.4 and later handle AVIF fine. Using a picture element or a plugin that adds a WebP or JPEG fallback prevents any break.
Does WebP work on all browsers?
Effectively yes. WebP is supported by more than 97 percent of browsers, including Safari since version 14 in 2020. That near-universal coverage means you can serve WebP without a fallback and expect it to display for almost everyone.
Does WordPress support AVIF?
Yes. WordPress core added WebP support in version 6.1 and AVIF in 6.5, so it can generate both natively. For automatic delivery with fallbacks, an image optimization plugin or a CDN that negotiates formats handles the details for you.
How do I add an AVIF fallback?
Use the HTML picture element with an AVIF source, an optional WebP source, and a JPEG image as the final fallback, so the browser picks what it supports. In practice, a WordPress image plugin or CDN generates and serves this automatically without you writing the markup.
The bottom line
The AVIF-versus-WebP debate misses the real point: broken images on Safari come from serving a next-gen format with no fallback, not from the format itself. WebP is the safe, near-universal default you can serve alone, and AVIF is the smaller, faster option as long as you keep a fallback behind it. Let a WordPress plugin or CDN handle the delivery, and you get the speed with none of the breakage. For more on building faster, better sites, browse The Other Stream’s Web Design and Tech sections.