Resize
Free Online Image Converter — HEIC, WebP, PNG, JPG, AVIF & 20+ Formats
How to Convert Images Online
1Upload your image
Click the upload button or drag and drop your image. JPG, PNG, WebP, AVIF, GIF and HEIC are supported.
2Choose a width
Enter a target width in pixels or pick a preset. The height is calculated automatically to keep your image's proportions.
3Download
Click Resize and download your resized image. For multiple files you get a ZIP archive.
Supported Image Formats
HEIC
Apple photo format used by iPhone and iPad. High quality with small file size.
HEIF
High Efficiency Image Format — same as HEIC, used on Apple devices.
WebP
Modern image format by Google. Up to 30% smaller than JPG with the same quality.
PNG
Lossless format that preserves every pixel. Best for screenshots and logos.
JPG
Universal format for photos. Supported everywhere, great balance between quality and file size.
GIF
Classic format for simple animations. Supports transparency and up to 256 colors.
BMP
Uncompressed bitmap format. Maximum quality but very large file size.
TIFF
Professional lossless format used in printing and photography.
AVIF
Next-gen format with excellent compression. Up to 50% smaller than JPG.
PPM
Portable Pixmap format used in Unix/Linux environments.
HDR
High Dynamic Range format storing extended brightness data.
FITS
Flexible Image Transport System used in astronomy and science.
PDF
Portable Document Format. Convert PDF pages to JPG, PNG or WebP images.
AVIF vs WebP vs HEIC vs JPG
Quick comparison to help you choose the right format
AVIF
- Size: Up to 50% smaller than JPG
- Browsers: Chrome, Firefox, Safari
- Transparency: ✓
- Best for: Web performance
WebP
- Size: 25-35% smaller than JPG
- Browsers: All modern browsers
- Transparency: ✓
- Best for: Web compatibility
HEIC
- Size: ~50% smaller than JPG
- Browsers: Safari only
- Transparency: ✓
- Best for: iPhone storage
JPG
- Size: Baseline
- Browsers: All browsers & apps
- Transparency: ✗
- Best for: Universal sharing
Frequently Asked Questions
- How do I resize an image without losing quality?
- Make it smaller, not larger. Downscaling with a high-quality algorithm (Convertify uses libvips with a Lanczos3 final pass) produces a result that's visually identical to the original at the new size. Enlarging an image past its original dimensions is what causes visible quality loss, because the missing detail can't be recreated.
- How do I resize an image to a specific width in pixels?
- Upload your image, enter your target width (or pick a preset like 1920, 1280, 800, or 640 pixels), and Convertify resizes it to exactly that width. The height is calculated automatically to keep your image's proportions.
- Does resizing an image reduce its file size?
- Yes, significantly. Because file size tracks the total pixel count, reducing the width cuts the file weight sharply. In our tests, resizing a 4.5 MB photo to 1920 pixels wide cut it to about 524 KB, an 88% reduction, and to 800 pixels brought it under 110 KB.
- What's the difference between resizing and compressing an image?
- Resizing changes the pixel dimensions (how wide and tall the image is). Compressing keeps the dimensions the same but reduces file weight by storing the pixels more efficiently. If your image's dimensions are already fine and you only need a smaller file, use compression. If the image is physically too large, resize it.
- What width should I resize my image to for a website?
- For full-width hero and banner images, 1920 pixels is the standard, and it matches the most common desktop resolution. For blog and article body images, 1200 pixels works well. For smaller in-content images, 800 pixels is usually enough.
- Will resizing keep my image's aspect ratio?
- Always. Convertify resizes by width and calculates the matching height automatically, so your image is never stretched or squashed. The proportions are always preserved.
- Why can I only set the width and not the height?
- Setting only the width guarantees your image keeps its exact proportions, and the height follows automatically. Forcing both a specific width and height would either distort the image or require cropping. For exact width-by-height dimensions with cropping, a dedicated crop tool is coming.
- Can I enlarge (upscale) an image with Convertify?
- Convertify is built for making images smaller. Enlarging an image beyond its original size can't recover detail that was never captured, so the result would look soft or blurry. For genuine enlargement you'd need a dedicated AI upscaling tool.
- What image formats can I resize?
- JPG, PNG, WebP, AVIF, GIF, and HEIC. Your image keeps its original format after resizing: a JPG stays a JPG and a PNG stays a PNG.
- Is it safe to upload my images?
- Yes. Files are processed on our server and automatically deleted within a few hours. They're never shared or used for any other purpose, and there's no signup required.
- How do I resize a photo to fit under an upload size limit?
- Start by resizing to a smaller width, which alone usually brings large photos well under common limits. Our data shows a 4.5 MB photo drops to about 250 KB at 1280 pixels and around 107 KB at 800 pixels. If you need to stay at full dimensions but reduce weight, use compression instead.
- Can I resize several images at once?
- Batch resizing is on the roadmap. For now, resize images one at a time, and each takes only a second.
What resizing an image actually does
Resizing changes your image's pixel dimensions, meaning how many pixels wide and tall it is. If you have a large photo straight from a phone or camera (often 4000+ pixels wide and several megabytes) and you need it smaller for a website, email, or upload form, resizing is what you want. Convertify resizes by width: you choose how wide the result should be, and the height is calculated automatically to keep the original proportions. Your image is never stretched, squashed, or cropped.
Resize or compress: which one do you need?
Before you resize, it helps to know whether you actually need smaller dimensions or a smaller file size, because they are not the same thing. If your goal is fewer pixels (for example, shrinking a 4284 pixel wide photo to 1920 pixels for a web banner), you are in the right place. If you need to keep the same dimensions but reduce the file's weight to fit an email or upload limit, that is compression: try compress JPG, compress PNG, or compress WebP instead. In practice resizing a large photo down also dramatically reduces its file size, often more effectively than compression alone, which is why most people uploading oversized camera photos only need this page.
Real data: how much file size drops at each width
We took 24 full resolution photos from an iPhone (4284 x 5712 pixels, averaging 4.5 MB each as JPEG) and resized them to common web widths through our own engine. The results below show how sharply file size drops as width decreases, because file size scales with the total pixel count, and pixel count falls with the square of the width.
File size by target width (measured on 24 real photos)
| Target width | Average file size | Reduction vs 4.5 MB original | Best for |
|---|---|---|---|
| 1920 px | 524 KB | -88% | Full width web banners, hero images |
| 1280 px | 249 KB | -94% | Email attachments, large content images |
| 800 px | 107 KB | -97% | In content, blog body, sidebar images |
| 640 px | 72 KB | -98% | Thumbnails, avatars, previews |
Why the file size drops so steeply
When you halve an image's width, you also halve its height (proportions are kept), so the total pixel count drops to roughly a quarter. File size for photographic content tracks pixel count closely, so going from 4284 pixels wide down to 1920 removes about 88% of the file weight in a single step. Cutting further to 800 pixels removes about 97%. This is why resizing is the most powerful first move for anyone dealing with oversized photos, because it does far more than tweaking compression quality ever could. If you also want to change the file type while you are at it, convert afterwards with tools like JPG to WebP or PNG to WebP for even smaller files.
Recommended widths by use case
Choosing the right width depends on where the image will be used. For full width hero and banner images on a website, 1920 pixels is the practical standard, since 1920 x 1080 is the most common desktop screen resolution worldwide, so a 1920 wide image covers the vast majority of displays without waste. For blog and article body images, 1200 pixels is a strong default: it suits most content columns and leaves headroom for high density (Retina) screens. For in content, sidebar, and supporting images, 800 pixels is usually plenty and keeps files light. For email, aim around 1280 pixels and a file under roughly 200 KB so the message stays deliverable. For profile photos and avatars, 400 to 640 pixels covers most platforms, which display them small. For thumbnails and previews, 150 to 300 pixels is enough.
Does resizing reduce quality?
When you make an image smaller (downscaling), the answer is essentially no, as long as a good algorithm is used. Convertify resizes through libvips, which performs the final stage of every reduction with a Lanczos3 filter, the same high quality method used in production image pipelines. At normal viewing sizes the resized image is visually indistinguishable from the original. Two honest caveats apply. First, most camera and phone photos are already JPEG compressed, so any re-save loses a tiny, generally invisible amount of detail. Second, enlarging an image beyond its original size (upscaling) cannot add detail that was never captured, so Convertify is built for making images smaller, not larger.
Why Convertify resizes by width, and what is next
Setting only the width and letting the height follow automatically guarantees the proportions stay correct and prevents the single most common resizing mistake: a stretched or squashed image. If you need an exact width and height, for example a perfect 1080 x 1080 square for a social profile or a 16:9 crop for a video thumbnail, that requires cropping away part of the image, which is a separate operation, and a dedicated crop tool is on the way. Your image keeps its original format after resizing, so a JPG stays a JPG and a PNG stays a PNG. Need to combine several resized images into one document? Try images to PDF. Files are processed on our server and automatically deleted within a few hours, with no signup, no watermark, and no limit on how many images you resize.