"Compress without losing quality" is the SEO version of a lie. Every compression either throws information away (lossy) or works within strict mathematical limits (lossless). You can't have both a dramatically smaller file and bit-exact output. What you can have is a smaller file whose quality loss is imperceptible.
Lossless vs lossy, in one sentence each
- Lossless: shrinks the file by finding clever ways to encode the exact same pixels. Usually gives modest savings (~20–40%).
- Lossy: throws away pixel detail that the eye is unlikely to miss. Gives dramatic savings (often 90%+) but you can't un-throw it.
When to pick which
If you're going to re-edit, re-crop, or layer this image again — lossless. Repeated lossy compression degrades images quickly (every re-save loses more information).
If this is the final version that will just be viewed — lossy is fine. Web photos, email attachments, and social media posts are all end-of-the-line uses.
Format choices ranked by compression
- WebP — smallest, both lossy and lossless modes. Modern browsers only.
- JPG — good lossy compression for photos. Universal support.
- PNG — lossless, larger, supports transparency.
- TIFF / BMP — essentially uncompressed. Don't use these unless you have a specific reason.
Practical workflow
- Start with the highest-quality source you have. You can always make it smaller — you can't make it bigger without blurring.
- Decide: final use? → lossy. Working copy? → lossless.
- Convert to the appropriate format via Formatly. For lossy targets (JPG, WebP) the conversion uses sensible default quality settings.
- Check the output. If it's too small in quality, keep the source and go up a quality tier; if the file is larger than you need, go down.
Don't stack lossy conversions
Each lossy save loses some detail. If you take a JPG, convert it to PNG, edit it, then convert back to JPG, you've done two lossy steps plus whatever the editor did — the output is meaningfully worse than the original. For editing, stay in a lossless format (PNG, TIFF) until the final export.
Converting with Formatly
- JPG → PNG (lossless preservation)
- PNG → JPG (shrink for sharing)
- For WebP targets or other pairs, drop the file on the home page and pick from the dropdown.