TL;DR:
The best image optimization plugins for WordPress balance compression quality, format conversion, and lazy loading to fix Core Web Vitals failures—but choosing the right one depends on whether you need granular control or an all-in-one solution.
If you’ve got improperly sized images on your website, it can tank your loading speed and LCP scores on desktop and mobile. And considering that a page that loads between 1-3 seconds has a bounce rate of 32% (90% for websites that take five seconds to load a page), you’ll need to optimize to get those times down.
Thankfully, there’s a ton of plugins that can help.
Some people think that compressing the images is all they need to do, but that’s very far from the truth, and all experts know this.
The best image optimization plugins that actually improve your Core Web Vitals scores tackle three separate problems:
- File size (through compression and WebP conversion)
- Delivery timing (lazy loading that doesn’t break your hero image),
- Dimension handling (responsive sizing that prevents layout shifts).
We tested the most popular options on real WordPress sites, tracking before-and-after results in PageSpeed Insights and GTmetrix. Some delivered dramatic improvements. Others barely moved the needle despite impressive marketing claims.
This comparison cuts through the noise with actual compression results, pricing breakdowns, and warnings about conflicts that waste your time. Let’s go.
Why WordPress image optimization plugins matter
Images make up over 60% of your page weight and are the primary reason mobile LCP scores fail. While WordPress compresses images automatically on upload, it’s not enough to deliver pages fast. It doesn’t convert to modern formats, handle responsive sizing, or implement lazy loading—leaving you with bloated files that slow everything down.
Proper optimization delivers faster load times, better Core Web Vitals scores, improved search rankings, and lower bounce rates.
Do you need a plugin for proper image optimization, though? It depends. You can resize everything in Photoshop manually or run files through TinyPNG before uploading. But TinyPNG’s free tier limits you to 20 images at a time with a 5MB cap. For sites with hundreds of images, that’s unsustainable. For this reason, WordPress plugins are generally the best and easiest way to achieve image optimization.
Advanced optimization methods that fix speed audits
Compression alone doesn’t fix slow images. You’ll also have to deal with three other audit features that can affect your Core Web Vitals score:
- Properly size images: Gets fixed by responsive sizing and adaptive delivery that serves the right dimensions to each device—mobile users don’t download desktop-sized files.
- Defer offscreen images: Lazy loading is the solution here. Just make sure you don’t apply it to your hero image, because you can destroy LCP. Smart plugins automatically exclude above-the-fold images.
- Serve images in next-gen formats: Look for plugins that provide WebP conversion as a baseline. WebP files are 25-35% smaller than JPEGs at equivalent quality with zero visual compromise.
💡 Extra method: CDN delivery
We mentioned three audit features, but it’s a crucial feature to add. That’s because it provides images from servers close to visitors, speeding up load times globally regardless of where your hosting sits.
When all four work together, you can actually fix the technical failures that tank PageSpeed scores. Smaller file size isn’t the full picture… pun definitely intended.
Best image optimization plugin: quick comparison
Before diving into individual tools, let’s run you through how we tested them first.
We installed the free version of each plugin on a demo WordPress site and optimized a single page containing a mix of photographic JPEGs, PNG graphics, and hero images. Settings were kept at default recommended levels (typically lossy compression around 80% quality) to reflect what most users would actually implement.
We then measured file size reductions, checked PageSpeed Insights scores, and noted any warnings or conflicts.
Quick comparison table:
| Plugin | Free Tier | WebP Support | AVIF Support | Lazy Loading | CDN Included | Starting Price |
| NitroPack | 1,000 pageviews/month | Yes | No | Yes | Yes | $8/month |
| EWWW Image Optimizer | Unlimited lossless | Yes (free local / paid cloud) | No | Yes | No | $7/month |
| Smush | Feature-limited | Yes (Pro only) | No | Yes | No | $6/month |
| Imagify | 20MB/month (~200 images) | Yes | Yes | No | No | $4.99/month |
| Optimole | 5,000 visitors/month | Yes | No | Yes | Yes | $22.50/month |
| ShortPixel | 100 images/month | Yes | Yes | Yes | Optional add-on | $4.99/month |
The results were revealing. Some plugins delivered exactly what they promised. Others had hidden limitations that only became obvious after installation.
⚡ Five tools focus specifically on image optimization—compression, format conversion, and file size reduction. They excel at making images smaller and faster to load, but they don’t handle caching, code optimization, or other site-wide performance issues. If you need those features, you’ll need additional plugins or an all-in-one service (like NitroPack).
Want to see immediate results?
Best image optimization plugins tested
Now for the in-depth reviews.
We used each tool’s default settings and recommendations, and ensured that settings like lazy loading and WebP conversions were enabled (if available on the free trial), so we could show each plugin’s capabilities fully. We’re also running the test five times and taking the best numbers.
Here’s our baseline for desktop:
And for mobile:
1. EWWW Image Optimizer
EWWW is one of the quickest plugins to set up, but it took the longest time to optimize images (around ten minutes). However, for a free plan, it allowed us to optimize every single image on the demo site, making it a decent choice for cash-strapped websites that need a quick fix for their web vitals.
Key features:
- Unlimited lossless compression (free, local processing).
- WebP conversion (paid cloud service only).
- Lazy loading included.
- Works with images on external CDNs.
- Privacy-focused local processing option.
Pricing: Free for local processing. Cloud service starts at $7/month for compression credits.
Page Speed Insights
PageSpeed scores didn’t change much on desktop, improving our overall score by just two points. Additionally, our LCP was reduced by 0.3 milliseconds, which still wasn’t enough to put us into the green.
There was some improvement in our base mobile scores. LCP time was reduced, sitting between 8 and 9 seconds, though FCP didn’t change by much. While it’s improved our baseline scores, it’s not enough to make any real difference.
2. Smush
Smush is one of the most popular plugins with 1 million+ installations, but the free version showed minimal compression in our tests.
Key features:
- Lazy loading (free).
- WebP conversion (Pro only).
- CDN delivery (Pro only).
- Unlimited optimization (Pro only).
- Strong security and code quality.
Pricing: Free version available. Pro starts at $6/month (billed annually) for unlimited sites.
PageSpeed Insights
Desktop results largely mirror EWWW, though with a better LCP on average after five tests.
For the mobile site, the overall score was 61, with LCP just under 10 seconds and FCP around the five-second mark.
🙂 Looking for green scores on both desktop and mobile?
The first two tools delivered modest improvements—but still not enough to fix failing Core Web Vitals scores. Desktop performance stayed relatively stable, but mobile LCP remained stuck above 8 seconds across both plugins.
If you need real fixes rather than incremental gains, one tool on this list actually delivered green scores on mobile and near-perfect desktop performance in our tests.
Or keep reading to see how the remaining standalone image optimizers performed first.
3. Imagify
From the W3 Rocket Team, Imagify comes with a fairly restrictive free plan (only optimizing about 11% of our images) based on credits.
Key features:
- Three compression levels: Normal (lossless), Aggressive (lossy), Ultra (maximum).
- WebP and AVIF conversion (both formats).
- Bulk optimization with one click.
- Automatic backup of originals.
- Detailed before/after statistics.
- Seamless WP Rocket integration.
No lazy loading or CDN—this is purely image optimization. You’ll need separate plugins for other performance features.
Pricing: Free 20MB/month (~200 images). Paid plans: $4.99/month for 5,000 images or $9.99/month unlimited. One API key for unlimited sites.
PageSpeed Insights
Desktop remains much the same, with LCP fluctuating between 1.6 and 1.8 seconds. Overall scores remained around 92.
The mobile site has an overall score of 73, though LCP scores ranged from 9 to 10 seconds, and FCP remained around 2 seconds across 5 tests. All in all, a good score despite the restrictive free plan.
4. Optimole
Optimole is a cloud-based service with real-time optimization and built-in CDN. And that’s all included on the free plan. That being said, it’s difficult to figure out how long it takes Optimole to optimize… we just know that it took the longest out of every tool. The only indication you get that your images are being optimized is a blank icon on your pages.
Key features:
- Adaptive delivery (adjusts to the visitor’s device and connection).
- Built-in CDN included.
- Intelligent cropping and watermarking.
- Responsive image sizing without configuration.
- Network-based optimization (lower quality on slow connections).
Pricing: Free for 5,000 visitors/month. Paid from $22.50/month for 25,000 visitors.
PageSpeed Insights
Desktop remained consistent, with a score of 92, and an LCP that stuck around 1.8 seconds.
In mobile performance, Optimole performed significantly worse. It had an overall score between 62 and 65, with LCP being consistently over 10 seconds. FCP never fell below five.
5. ShortPixel
ShortPixel has a free trial and gives a familiar story. It’s very limiting, as it only allows us to optimize 11 images. That being said, the dashboard is clean and easy to use, and it’s simple to set up before bulk optimizations begin.
Key features:
- Lossy, glossy, and lossless compression options.
- WebP and AVIF format support (both next-gen formats).
- Cloud processing offloads server work.
- Lazy loading included.
- Monthly optimization reports.
- Original images backed up separately.
- No file size limits.
Pricing: Free 100 images/month. $4.99/month for 5,000 images or one-time credit packages available.
PageSpeed Insights
Because of the limited image optimization, the desktop and mobile numbers are very close to our benchmark tests. Desktop sits at 92 overall score, with a marginally better LCP.
Mobile scores also tell a similar story. General score hovers between 62 and 64, and the LCP is between 8 and 11 seconds.
All-in-one speed optimization services
You may have noticed that, even if a free plan allowed us to optimize all images, it still couldn’t give us green scores on mobile or reduce LCP on desktop.
That’s because image optimization is just one piece of the puzzle. If you’re dealing with multiple performance issues—slow caching, render-blocking JavaScript, unoptimized fonts—stacking separate plugins gets messy fast.
This is where all-in-one services like NitroPack make sense.
6. NitroPack
NitroPack differs from the tools above. It’s a complete site speed optimization service that handles image optimization as one component within a broader 60+ feature stack.
“I have scoured the net for the best website optimisation tool, from WP Rocket to Cloudflare, W3 Total Cache, to EWWW Image Optimizer, WP Fastest Cache to Lightspeed Cache, and so on, but the best happened with Nitropack.” – Write Wing Media
Key features:
- Lazy loading with automatic LCP exclusion (Plus+ plans).
- Preemptive image sizing adds width/height attributes to prevent CLS.
- Adaptive image sizing serves device-appropriate dimensions (Plus+ plans).
- WebP conversion (automatic, with fallback).
- Lossy and lossless compression options.
- Built-in global CDN (100+ countries, no extra cost).
- Video facades for YouTube/Vimeo embeds.
- Advanced caching, code minification, and font optimization.
Before-and-after testing shows meaningful improvements. According to NitroPack’s test data, 69.91% of NitroPack-optimized sites pass Core Web Vitals, compared to 52.1% of non-optimized origins. This was evident when we ran our demo site with NitroPack.
First, here are the desktop results: 99 on overall performance – easily the highest of the bunch.
And on top of that, we finally got into the green with our mobile site.
Getting your vitals right can make a huge difference to your web business, too. A case study with OfficeRnD showed site speed improvements directly correlating with a 12.5% conversion rate increase.
Limitations to note:
- No AVIF support (only WebP).
- No per-image control or granular optimization settings.
- No detailed image-specific statistics.
- Pageview-based pricing can get expensive at scale.
- Requires disabling other optimization plugins to avoid conflicts.
Pricing: Free plan with 1,000 pageviews/month. Paid plans start at $8/month for Starter (8,000 pageviews) or $22/month for Plus (40,000 pageviews) with advanced features.
You can see exactly what NitroPack can do for your website, even before opting for a free plan.
Test NitroPack yourself
Common mistakes that waste your time
Even the best image optimization plugin won’t help if you configure it wrong. Here are the traps that kill performance despite proper compression:
- Lazy loading the hero image: This destroys LCP scores because your largest above-the-fold element loads late. NitroPack automates this exclusion on Plus+ plans, but with free plugins or basic plans, you need to manually exclude the hero filename in settings.
- Running two plugins that both convert to WebP or handle lazy loading: This creates conflicts where both plugins try to process the same images. NitroPack replaces 3-5 separate plugins (caching, image optimization, CDN, minification, lazy loading), so disable other optimization tools if you’re using it.
- Expecting big gains from free lossless-only compression: Lossless barely moves the needle—typically 10-15% reduction. Real performance improvements require lossy compression or next-gen formats.
- Ignoring upload and bandwidth limits. Optimole’s 5.7MB upload cap means you can’t even upload the oversized images it’s supposed to fix. NitroPack’s Starter plan includes 5GB/month CDN bandwidth, which image-heavy portfolios or ecommerce sites can exhaust quickly. Check limits before committing.
- Trusting vague “X% savings” claims without checking for yourself: Marketing numbers don’t reflect your specific images. Run PageSpeed Insights before and after to verify actual improvements.
Final verdict: Which is the best image optimization plugin for WordPress?
The right choice depends on your constraints.
Imagify works well for photographers needing AVIF support and per-image control. Smush Free covers basic optimization without monthly costs. ShortPixel’s unlimited plan ($9.99/month) offers good value for agencies.
For users who want one service fixing all image-related audits—properly sizing images, lazy loading, next-gen formats—plus coordinated caching and code optimization, NitroPack is the best option.
Whatever you choose, verify results with PageSpeed Insights before and after. Real metrics beat marketing claims.
⚡ Ready to fix all speed issues at once?
Try NitroPack’s free plan—no credit card required.
FAQs
Can I use two image optimization plugins?
No, and you shouldn’t try. Running two plugins that both handle WebP conversion or lazy loading creates conflicts where both attempt to process the same images. This breaks functionality, slows your site, and wastes server resources.
Stick with one comprehensive solution or carefully disable overlapping features if you must combine tools. For example, if you’re using NitroPack, disable WebP conversion in ShortPixel to prevent conflicts.
How do I speed up images in WordPress?
Start with compression—use lossy mode for most images to reduce file sizes by 70-90%. Convert to WebP format for better compression than JPEGs and then enable lazy loading for below-the-fold images (but never your hero image). Use responsive sizing so mobile visitors don’t download desktop-sized files.
Finally, deliver through a CDN to reduce geographic latency. Most image optimization plugins automate these steps once configured.
Is AVIF better than WebP?
Yes, technically. AVIF provides 20-30% better compression than WebP at equivalent quality levels. However, browser support still lags—Safari only added full AVIF support in 2023, and older browsers don’t support it at all.
WebP has universal modern browser support and remains the practical choice for most sites. If your plugin offers AVIF (like Imagify or ShortPixel), enable it alongside WebP as a progressive enhancement.
Which image optimizer is free?
All the plugins in this comparison offer free tiers. EWWW provides unlimited lossless compression for free. Smush Free includes basic optimization and lazy loading. Imagify gives you 20MB monthly (about 200 images). ShortPixel offers 100 images per month. Optimole provides 5,000 visitors monthly. NitroPack’s free plan includes 1,000 pageviews. However, free tiers have limitations—expect minimal compression savings and missing features like WebP conversion or bulk optimization.
