The format you save an image in affects its file size, quality, and compatibility — sometimes dramatically. A photograph saved as PNG can be five times larger than the same photo saved as JPG, with no visible difference. A logo saved as JPG instead of PNG can look blurry around the edges.
Here’s how to choose without overthinking it.
The quick answer
Use JPG for: photographs, anything with lots of colors, images for email.
Use PNG for: screenshots, logos, graphics with a transparent background, anything where text sharpness matters.
Use WEBP for: images on a website, anywhere you want the smallest possible file with good quality.
Have an iPhone photo in HEIC? Convert it to JPG for sharing — most apps and websites don’t support HEIC.
If you just need a fast answer, that’s it. The rest of this post explains the reasoning.
When to use JPG
JPG is a lossy format, which means it achieves small file sizes by discarding some image data. At normal quality settings — around 75-85% — the difference is invisible to the human eye. A 6MB photo from your phone can typically become a 1MB JPG with no perceptible quality loss.
Use JPG when:
- The image is a photograph or contains lots of color gradients
- You’re sending photos by email or text
- You’re uploading to social media (Instagram, Facebook, Twitter all work with JPG)
- File size matters more than pixel-perfect accuracy
- Transparency is not needed
Avoid JPG when:
- The image contains text or fine lines (JPG compression makes edges look blurry)
- You need a transparent background
- You’re saving a logo or icon that needs to look crisp at any size
When to use PNG
PNG is a lossless format — it never discards image data, so quality is always preserved exactly. The trade-off is larger file sizes compared to JPG for photographic content.
Use PNG when:
- The image has a transparent background (logos, icons, stickers, anything that overlays other content)
- It’s a screenshot, especially one containing text or UI elements
- Sharpness around edges and text matters
- You need pixel-perfect accuracy for design work
Avoid PNG when:
- The image is a photograph with no transparency — JPG or WEBP will be much smaller
- You’re uploading to a website and load speed matters
When to use WEBP
WEBP is a modern format developed by Google that outperforms both JPG and PNG on file size at similar quality. It supports both lossy and lossless compression, and it supports transparency.
Use WEBP when:
- You’re optimising images for a website and want the smallest possible files
- You want to replace JPG images with something smaller at the same quality
- You want transparency support with smaller files than PNG
The catch with WEBP:
Browser support is now excellent — Chrome, Safari, Firefox, and Edge all handle WEBP. But some older software and email clients still can’t open WEBP files. If you’re sending to someone else rather than publishing to a website, JPG is safer for compatibility.
What about HEIC?
HEIC is Apple’s format for iPhone photos. It produces smaller files than JPG at the same quality, which is why iPhones use it by default.
The problem is compatibility. Windows, most websites, and many apps can’t open HEIC files without extra software. If you’re sharing photos with people who don’t use Apple devices, converting to JPG first avoids the “I can’t open this” problem.
nosend.io converts HEIC to JPG directly in your browser, with no upload required.
A note on re-saving files
One practical thing worth knowing: every time you save a JPG, you lose a little quality. If you open a JPG, edit it, and save it again as JPG, you’re compressing an already-compressed file. Over multiple saves, the quality degrades noticeably.
If you’re doing any editing, work in PNG or a lossless format and convert to JPG as the final step. Never re-save a JPG as JPG multiple times.
Choosing a format in nosend.io
nosend.io compresses images in your browser without uploading them anywhere. When you drop files onto the page, you can choose JPEG, PNG, or WEBP as the output format regardless of what you dropped in. Drop an iPhone HEIC, output a WEBP. Drop a PNG screenshot, output a JPG. The conversion happens locally on your device.
The bottom line
- Photos going to email or social media: JPG
- Screenshots and logos: PNG
- Images going on a website: WEBP
- iPhone photos you want to share: convert HEIC to JPG
The format choice takes five seconds and can make a meaningful difference in file size, quality, and whether the recipient can open the file at all.
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