Image Converter
Convert images between PNG, JPG, WebP, BMP and ICO. Quality control and before/after size comparison included: everything is processed locally in your browser.
Only applies to JPEG and WebP
How to use
- Drop an image onto the dashed zone, or click it to pick a file from your device.
- Choose PNG, JPEG, WebP or BMP from the "Output format" dropdown.
- When converting to JPEG or WebP, drag the quality slider to tune compression: lower values make smaller files with lower quality.
- Click "Convert & download": the converted file is saved automatically and the before/after sizes are shown.
- Click "Clear" to reset and start over.
FAQ
Is my image uploaded to a server?
What happens to transparent areas?
Can I convert to GIF or ICO?
When should I use WebP?
How to use
- Import the image
Click the dashed zone or drop a file onto it. PNG, JPG, WebP, GIF and BMP inputs are accepted, one file at a time, fully in your browser.
- Pick the target format
Open the output-format dropdown and choose PNG, JPEG, WebP or BMP. The hint line above shows the source format and pixel dimensions so you can double-check.
- Tune quality for lossy output
The quality slider only affects JPEG and WebP. The default 90% balances quality and size; drop to around 70% for smaller files when converting photos.
- Convert and download
Press the convert button and the file saves at once. Original size, converted size and the change percentage appear below for comparison.
- Reset before the next file
Click Clear to reset the panel and drop leftover settings, then load the next image. The same routine works through small batches quickly.
About this tool
Each format has its own job. PNG is lossless and keeps transparency, which suits screenshots and icons. JPEG compresses photos heavily with slight quality loss. WebP usually gives the smallest files and still supports transparency. BMP stores raw pixels and shows up mostly in legacy systems. Converting decodes the file and re-encodes it in the new format, right on a Canvas in your browser. Nothing touches a server, and there is no upload size ceiling.
Office workers convert design PNGs to JPEG to meet upload limits. BMP exports from old software become universally accepted files after one conversion. Site owners standardize on WebP for faster loading. The reverse direction is common too, for example a JPG converted to PNG before retouching or background removal. The before-and-after size comparison shows whether each format change paid off.
How it works
Size changes after conversion come from the encoders themselves; the pixels stay the same and only the coding changes. PNG applies prediction filters followed by DEFLATE entropy coding, a pairing that works best on flat color areas, text and interface screenshots. The filter shrinks differences between neighboring pixels first, then DEFLATE squeezes repeated byte runs. Lossless WebP codes the same pixels with a smarter scheme and often lands another 20-30% smaller on photos. BMP barely compresses at all. At 32-bit color every pixel costs 4 bytes, so a 1920×1080 frame runs about 8.3MB whatever it shows. That fixed cost is a large part of why the format has faded.
Two rules keep conversions safe. Lossy-to-lossless output never improves quality: it freeze-frames the file as it currently looks while the size grows. Lossless-to-lossy conversions deserve restraint too, because every JPEG re-save reruns quantization and the ringing deepens each time. Decide the target format first and convert once. Keep either the converted result or the original for the long term. An untouched source file is the escape hatch that lets any conversion be redone.
When to use it
- Passing format whitelists
Many internal upload forms accept only JPG or PNG extensions and reject WebP outright. Convert to JPEG, check the size comparison, and the file passes while also revealing whether the platform enforces a separate size cap.
- Rescuing legacy BMP exports
Older finance and industrial software exports BMP files of several megabytes that many viewers handle badly. Converting to PNG typically shrinks them dozens of times over with zero quality loss, easing sharing and archiving alike.
- Moving icons onto the web
Transparent PNG icons convert to WebP with the alpha channel intact and roughly 30% smaller still. That lightens every page referencing them. The before-and-after numbers show file by file whether the switch paid off.
Tips & tricks
- Animated GIFs export only their first frame; keep the original file if the motion matters.
- JPEG and BMP have no alpha channel, so transparent regions turn white. Pick PNG or WebP output when transparency must survive.
- WebP typically runs about 30% smaller than JPEG at similar quality. Standardizing a site on WebP pays off quickly.
Things to watch
- Lossless output adds no sharpness
Lost detail cannot be recovered: converting to a lossless format only freezes the current quality while the file grows. Real improvement requires going back to a higher-quality original, not another conversion pass.
- Repeated JPEG re-saves compound loss
Each save reruns quantization, deepening ringing around edges and blocky textures a little further. Settle on a format, convert once, then keep PNG or the original as the working copy.
- BMP size ignores the picture
BMP stores raw pixels, four bytes each at 32-bit color, so 1920×1080 costs about 8.3MB even for a blank image. Pick any other format as an intermediate whenever file size matters.