How to Resize an Image Online — and Compress & Convert It Too
Almost every image problem on the internet is one of three things: the picture is the wrong size (too big in pixels for a form or profile), the file is too heavy (too many MB to upload or email), or it's the wrong format (a site wants JPEG and you have PNG). This guide fixes all three in a couple of minutes, for free, using PixTools — which works in your browser, so your pictures are never uploaded anywhere.
How to resize an image
- Open the PixTools home page and drop your image into the box (or tap to choose it). You'll see a preview with its current size in pixels and its file size.
- Stay on the Resize tab. Type the new width or height you need. With Lock aspect ratio on (recommended), the other side adjusts itself, so the picture never looks stretched.
- Or use a percentage preset — 50% makes the image half as wide and half as tall, which is a quarter of the pixels.
- Choose the output format (see the format guide below) and click Download resized image.
Tip: resizing smaller almost always makes the file lighter too. Resizing bigger than the original, on the other hand, can't add real detail — the picture will just get softer.
How to compress an image
- Load your image, then open the Compress tab.
- Move the quality slider. Start around 80: for most photos that's the sweet spot where the file shrinks a lot and your eyes can't tell the difference.
- Watch the result line — it shows the new file size and the exact percentage saved. Slide lower if you need an even smaller file (for example under a form's 200 KB limit), or higher if quality matters more.
- Download the compressed image.
JPEG vs WebP for compression? WebP usually wins — same look, smaller file. Choose JPEG when the place you're sending the picture to is old-fashioned about formats (some government and exam forms still are).
How to convert an image
- Load your image and open the Convert tab.
- Tap PNG, JPEG or WebP. The converted file size appears instantly.
- Download. The new file keeps your original's name with "-converted" added, so nothing gets overwritten or lost.
PNG vs JPEG vs WebP — when to use which
| Format | Best for | Transparency | File size |
|---|---|---|---|
| JPEG | Photos, and anywhere maximum compatibility matters (forms, older sites, email) | No — transparent areas become white | Small |
| PNG | Logos, screenshots, text, graphics with sharp edges; anything needing transparency | Yes | Larger (lossless) |
| WebP | Websites and blogs — photos and graphics at the smallest size, supported by all modern browsers | Yes | Smallest |
Simple rule: photo → JPEG, logo/screenshot → PNG, website image → WebP. And if a form or app rejects your file, convert to JPEG first — it's the format everything accepts.
The right sizes for social media
| Platform | Use | Size (px) |
|---|---|---|
| Square post | 1080 × 1080 | |
| Portrait post | 1080 × 1350 | |
| Story / Reel cover | 1080 × 1920 | |
| Shared photo | 1200 × 630 | |
| Cover photo | 1640 × 924 | |
| X (Twitter) | Post image | 1600 × 900 |
| YouTube | Video thumbnail | 1280 × 720 |
| Profile photo | 640 × 640 | |
| Post image | 1200 × 627 |
Resize to these numbers before posting and the platform won't crop or re-compress your picture as harshly.
Common questions
- A form says "image must be under 200 KB" — what do I do? Compress with the slider until the result line shows a size under the limit. If quality gets too low, resize the dimensions down a little as well — the two together shrink files fast.
- My PNG logo turned white-boxed in JPEG. That's expected: JPEG has no transparency, so transparent pixels are placed on white. Keep PNG or WebP if you need the transparent background.
- Will the website see my photos? No. PixTools processes everything inside your browser. Nothing is uploaded — you could even disconnect from the internet after the page loads and the tools would still work.