Changing an image's format sounds simple, and it usually is. The tricky part is choosing the right format, because each one handles quality, file size and transparency differently. This guide walks through the conversion step by step, explains which format to pick for each job, and covers the mistakes that make a converted image look worse or come out larger than expected.
What does converting an image actually do?
An image file is a grid of pixels saved with a particular method of compression. Converting reads those pixels and writes them again using a different method. The picture you see stays the same size and shape unless you change it, but three things can change along the way:
- File size, because every format compresses differently.
- Quality, if the new format is lossy (JPEG and lossy WebP) and you choose a lower quality.
- Transparency, which survives in PNG, WebP and ICO but not in JPEG.
Renaming `photo.webp` to `photo.jpg` is not a conversion. The data inside is still WebP, and strict apps will still reject it. A real conversion rewrites the file.
How to convert an image online, step by step
- Open the image converter on your computer or phone.
- Choose an image or drop it on the page. The file is uploaded as soon as you choose it.
- Under Output format, pick JPEG, PNG, WebP, GIF, TIFF, BMP or ICO.
- For JPEG and WebP, set the Quality. The default is the highest setting; lower values make a smaller file.
- Optional: use Quick edits to crop, rotate or flip, and Dimensions (px) to change the width or height.
- Check the size estimate, then select Download.
The conversion runs on Convertola's server. The converted file is deleted automatically after 15 minutes, and location and other metadata are removed unless you choose to preserve them. Animated and multi-page images are not supported, so export a single frame first if you have a GIF animation or a multi-page TIFF.
If you already know the pair you need, the format pages preselect it for you: WebP to JPG, PNG to JPG, JPG to PNG, JPG to WebP and PNG to ICO.
Which image format should you choose?
| You want to... | Choose | Why |
|---|---|---|
| Share or upload a photo | JPEG | Opened by almost every app, form and printer |
| Keep a transparent background | PNG or WebP | Both store an alpha channel; JPEG does not |
| Save a screenshot with sharp text | PNG | Lossless, so edges stay crisp |
| Speed up images on your website | WebP | Usually smaller than JPEG or PNG at similar quality |
| Make a favicon or a desktop icon | ICO | The format browsers and Windows expect for icons |
| Send a file to older software | JPEG or BMP | Widely supported by older programs |
JPEG (JPG)
JPEG is the standard for photographs. It uses lossy compression, which throws away detail that is hard to see in order to keep files small. It does not support transparency. `.jpg`, `.jpeg` and `.jfif` are all the same format.
PNG
PNG is lossless: every pixel is saved exactly. That makes it ideal for screenshots, diagrams, logos and anything with text, and it keeps transparent areas. The trade-off is size. A photo saved as PNG is often several times larger than the same photo as a JPEG. Our JPG vs PNG guide goes deeper into the differences.
WebP
WebP was designed for the web. It can be lossy or lossless and supports transparency, so it can replace both JPEG and PNG on a website. Some older apps and upload forms still refuse it, which is why so many people need to convert WebP to JPG.
ICO
ICO is the icon format used for favicons and Windows shortcuts. On Convertola, larger images are scaled to fit inside 256 × 256 pixels and the icon stores a PNG, so transparency is kept. Start from a square image so the icon is not squeezed.
GIF, TIFF and BMP
GIF is limited to 256 colors and is best kept for simple graphics. TIFF is common in scanning and printing workflows. BMP is uncompressed and large, but very old programs still read it. You can convert to and from all three.
What happens to transparency when you convert?
Transparency only survives if the output format supports it. Converting a PNG, WebP or ICO with a transparent background to PNG, WebP or ICO keeps it. Converting it to JPEG cannot keep it, because JPEG has no transparency at all: on Convertola, those areas are filled with white.
If you need a transparent background that you don't have yet, start with the background remover, download the PNG, and only then convert it if you need another format that supports transparency.
How to reduce an image to 100 KB, 50 KB or 20 KB
Upload forms often set a limit such as "JPG under 100 KB". The size estimate updates as you change settings, so you can adjust until the file fits:
- Choose JPEG or WebP. They have a quality slider; PNG doesn't.
- Lower the Quality a little at a time and watch the estimate.
- If the file is still too large, reduce the width under Dimensions (px). With the aspect ratio locked, the height follows automatically.
- Download when the estimate is under your limit.
There is no automatic "target size" button, so you stay in control of the balance between size and sharpness. Small limits like 20 KB usually need both a lower quality and smaller dimensions. A passport-style photo or a profile picture rarely needs to be wider than a few hundred pixels.
Resize, crop, rotate and mirror while converting
You don't need a separate editor for simple fixes. The converter includes:
- Dimensions (px): type a width or height, or use the scale. Lock the aspect ratio to avoid stretching.
- Crop: drag on the picture to choose the area that stays. Useful for squares and favicons.
- Rotate: turns the image in quarter steps.
- Flip horizontal / Flip vertical: mirrors the image, for example to reverse a selfie or a transfer print.
All the edits apply to the file you download, whatever format you pick.
Does converting reduce quality?
It depends on the formats involved:
- To PNG (or lossless ICO): no further loss. The pixels are saved exactly as they are decoded.
- To JPEG or WebP at high quality: a small, usually invisible change.
- To JPEG or WebP at low quality: visible blockiness, especially around text and sharp edges.
Converting a lossy file into a lossless one (for example JPG to PNG) does not restore detail that was already lost. It only stops further loss when you edit and save again. For the best results, convert once from the original file rather than converting a converted copy.
Converting images on a phone
The converter works in the browser on iPhone, iPad and Android, with nothing to install. Choose the image from your photos or files, pick the format and download. Note that iPhone photos are often saved as HEIC, which this converter doesn't read. To get JPEG photos from new pictures, set Settings > Camera > Formats to Most Compatible on the iPhone.
Troubleshooting
| Problem | What to try |
|---|---|
| "This file is not a supported image" | Use JPEG, PNG, WebP, GIF, TIFF, BMP or ICO. HEIC and AVIF are not supported |
| "Animated and multi-page images are not supported" | Export a single frame, then convert it |
| The file is too large to upload | The limit is 10 MB per image; resize it first in another app if needed |
| The JPG has a white background | The original was transparent; choose PNG or WebP to keep it |
| The PNG is much bigger than the JPG | Normal for photos; use JPEG or WebP for photographs |
| The download link no longer works | Converted files are deleted after 15 minutes; convert again |
Frequently asked questions
Is the image converter free?
Yes. It is free to use and doesn't need an account.
Which formats can I convert?
You can convert from JPEG, PNG, WebP, GIF, TIFF, BMP and ICO to any of those same formats. HEIC and AVIF are not supported.
Are my images kept on the server?
Images are processed on Convertola's server to create your download. The converted file is deleted after 15 minutes.
Is JPG the same as JPEG?
Yes. They are two extensions for the same format. Choosing JPEG as the output gives you a .jpg file.
How do I convert an image to a favicon?
Crop the logo to a square, choose ICO as the output and download. Larger images are scaled to fit inside 256 pixels, and transparency is kept.
Can I convert several images at once?
The converter handles one image at a time, which keeps the settings and the size estimate clear for each file.
Sources
- MDN Web Docs: Image file type and format guide
- Google for Developers: An image format for the web (WebP)
- W3C: Portable Network Graphics (PNG) Specification
- Library of Congress: JPEG File Interchange Format
Ready to convert? Open the Convertola image converter and pick the format you need.
