Guides
Guides
The questions a converter cannot answer. Which format to pick, what the trade-offs actually cost, and what happens to a file when you upload it somewhere.
Privacy and safety
- Is it safe to convert files online?What happens to your file when you upload it to a converter, what the real risks are, and how to tell whether a tool uploads at all.
- How to convert files without uploading themThree ways to convert a file without sending it to a server, what each costs you, and how to verify that nothing was uploaded.
Which format should I use?
- HEIC vs JPGHEIC is about half the size of JPG at the same quality. JPG opens everywhere. When each one is the right answer, and how to convert.
- WebP vs AVIFAVIF is 56% smaller than WebP on our test image, but far slower to encode. Measured figures, and a rule for choosing between them.
- PNG vs JPGPNG for screenshots, logos and transparency. JPG for photographs. Measured file sizes, and the failure modes of getting it backwards.
- The best image format for your websiteAVIF with a WebP fallback, for almost everything. Measured file sizes across five formats, and the exceptions worth knowing.
How it works
Practical how-tos
- How to open HEIC files on WindowsWhy Windows won't open your iPhone photos, the three ways to fix it, and which one is worth bothering with.
- How to reduce image file sizeFour ways to make an image smaller, in the order that actually works. Resize first, then change format, then compress.
- How to make a PDF smallerWhere PDF file size actually comes from, what genuinely reduces it, and an honest account of what this site cannot do.