Slow pages make people wonder if the site is trustworthy, modern, and well-maintained. Fast pages feel confident. They feel like the business behind them has things under control. And because images are often the heaviest thing on the page, image formats are one of the simplest places to win back speed without redesigning your whole life.
By the time you finish this article, you’ll know which format to use (AVIF, WebP, JPEG, PNG), when to convert, and how to serve modern images for your web project.
Table of Contents
Table of Contents
First: why images matter for conversion (yes, really)
Most visitors don’t think, “This site’s LCP is bad.” They think, “This feels slow.” And slow often turns into “I’ll come back later,” which is the polite version of “goodbye forever.”
Images affect that feeling more than you might expect because they are usually large files (especially hero banners and product photos), which are loaded early (e.g above the fold) and which are repeated across pages (category pages, galleries, blog feeds.)
When your images are lighter, pages snap into place sooner. That reduces friction, which helps keep people moving, scrolling, reading, and buying. It’s not magic. It’s just fewer bytes, delivered smarter.
The formats, explained like a normal person
There are four formats you’ll see constantly in modern web work. Each has a role. The trick is not picking one “best” format, but using the right one for the job.
JPEG: the classic photo format
JPEG is the old reliable. It works everywhere and it’s still fine for photos. The downside is that JPEG usually needs a bigger file size than newer formats to look equally good. In 2026, JPEG is often what you keep around as a fallback, not what you lead with.
Think of JPEG as the comfortable pair of sneakers you keep by the door. You might not wear them to a formal event, but you’re glad they’re there.
PNG: sharp edges and transparency, but often chunky
PNG is great when you need crispness: logos, diagrams, screenshots with text, images with transparency where edges need to stay clean.
PNG is also very good at being large. Use it for graphics, not big photographic images, unless you enjoy unnecessary page weight.
WebP: the practical modern default
WebP is a modern format that usually makes images significantly smaller than JPEG while still looking great. It can also handle transparency, which means it can sometimes replace PNG too.
If you want a “safe modern pick” that works in most workflows and improves performance quickly, WebP is often the answer.
AVIF: the “tiny file, great quality” option
AVIF can deliver excellent quality at very small sizes, especially for large photos like hero images and editorial photography. It’s often the best choice when you want maximum size reduction.
The trade-off is that some conversion workflows can be a bit slower or fussier than WebP, depending on your tools. That’s not a dealbreaker, it just means AVIF is best when you have a consistent process, not a one-off scramble.
If you only remember one rule, make it this: for photos, start with AVIF or WebP. For text-heavy graphics, keep PNG (or use lossless WebP). Keep JPEG as a reliable fallback.
The biggest mistake people make: converting without resizing
Here’s the truth that fixes more “slow site” problems than any fancy format debate: an oversized image is still oversized, even if it’s WebP.
If you upload a 4000px wide image and display it at 900px, visitors still download a file that was built for a billboard. Compression helps, but resizing is the real heavyweight move.
The order that works is:
- Resize to the dimensions you actually need
- Convert to a modern format
- Choose a sensible quality level
When you resize first, everything else gets easier. Smaller dimensions plus a modern format is where the big savings live.
What should you use where? Real-world answers
Let’s match formats to the places where they matter for UX and conversion.
Hero images and landing page banners
These are the first impression images. They’re usually big, and they load early, so they matter a lot. This gives you the best chance of a fast, polished first paint, especially on mobile.
Blog images and content marketing
Blog posts often have multiple images, and those add up quickly. WebP is typically the easiest win because it shrinks files without much drama. AVIF can shrink them further for large photos if your workflow supports it.
If you publish regularly, the best solution is the one you can repeat every week without thinking.
WooCommerce product images
Product pages are image factories: main image, gallery, thumbnails, related products, sometimes zoom images too.
The goal here is “fast but still premium.” Aggressive compression that makes products look smudgy can hurt trust. Customers may not know why, but they’ll feel it.
Screenshots, diagrams, and anything with text
Text inside an image is picky. Lossy compression loves to turn crisp letters into fuzzy outlines.
For screenshots and graphics with text:
- PNG is often the safest choice
- lossless WebP can work well if PNG is too heavy
- avoid low-quality JPEG here, unless you want “Why does this look blurry?” messages
Logos and icons
If you can use SVG, do it. It stays sharp at any size.
Compression settings that keep things looking good
You do not need to obsess over perfect settings. You need a starting point that works most of the time. You can even use online compression tools which will set things up optimally for you.
The simplest quality test is refreshingly low-tech: compare the original and the compressed image at normal viewing size. Then zoom in on areas that usually reveal problems: faces, gradients, text on signs, product edges. If you can’t tell the difference, ship the smaller one.
For text-heavy graphics: keep it crisp. A slightly larger image that looks clean is often better for trust than a smaller one that looks mangled.
The usual “we optimized images but it’s still slow” culprits
If you’ve optimized and nothing changed, it’s usually one of these:
The images weren’t resized, only converted. That’s the big one.
The most important image wasn’t optimized. Often the worst offender is the hero image or a large product photo above the fold.
Images got compressed multiple times. A designer exports a compressed JPEG, then someone compresses it again, then a plugin compresses it again. Quality drops, and file size improvements get smaller each time.
The fix is not more random compression. It’s a consistent system.
Final thought: fast feels trustworthy
People do not give your website a performance score in their head. They give it a feeling. Smooth, quick pages feel modern. Slow, heavy pages feel uncertain. And uncertainty is where conversions go to take a long nap.
Modern image formats are a rare win in website work: practical, measurable, and surprisingly impactful. Pick the right format, resize before you convert, keep fallbacks, and your site will feel faster in the only way that matters, to the humans using it.
