File format guides and how-tos
Plain-English guides to image and PDF formats: what they are, how they differ and how to convert between them. Each guide lists its sources, and the tools it mentions run in your browser.
AVIF vs WebP: myths, facts and which to pick
AVIF usually compresses harder than WebP, but WebP is older and better supported. Sort the myths from the facts and decide which suits your images.
Best image format for web, email, print and social
Which image format suits photos, logos and screenshots on websites, in email, for print and social media, using MDN, web.dev and Library of Congress guidance.
HEIC to JPG: why iPhone photos won't open
What HEIC is, why iPhone photos fail on some apps and sites, and ways to get JPG: the iPhone setting, Apple's import behaviour, and our planned HEIC tool.
How to convert a PDF to JPG, page by page
Turn each page of a PDF into a JPG image in your browser: pick the resolution, know the limits, and learn when PNG is the better choice for text pages.
How to convert JPG to PDF: your questions answered
Combine one or many JPG photos or scans into a single PDF in your browser. Covers page size, image order, limits and why the text is not searchable.
How to convert JPG to PNG (and what it can't fix)
How to turn a JPG into a PNG in your browser, plus the honest answers: it cannot restore lost detail, files usually grow, and transparency is not added.
How to convert PNG to JPG in your browser
Step-by-step: turn a PNG into a JPG in your browser, what happens to transparent areas, how file size changes and how to avoid a poor-looking result.
How to convert PNG to WebP (and when it backfires)
Convert PNG to WebP in your browser and keep transparency. We measured three test images: the photo shrank sharply, the small logo grew. Know before you switch.
How to convert WebP to JPG in your browser
Steps to turn a WebP image into a JPG in your browser, plus what happens to transparent areas, file size and quality, and when to keep the WebP.
How to extract pages from a PDF: a decision guide
Save only the pages you need from a PDF as a new file. Work out which route fits, how to type page ranges such as 1, 3-5, and what to check afterwards.
How to merge PDF files into one, step by step
Combine several PDFs into one file in your browser: choose the order, check the limits, and see what Mac Preview and Microsoft 365 offer instead.
Image format file sizes compared (we measured)
Exact byte sizes for one photo, one screenshot and one logo saved as PNG, JPEG, WebP and AVIF, with the method, tool versions and what the numbers do not show.
Is online file conversion safe? A checklist
A practical checklist for judging any online file converter: what HTTPS proves, where your file is processed, how long it is kept, and what to download.
JPG to WebP: a checklist before you convert
Check these points before turning a JPG into a WebP: browser support, double compression, file size that can grow, and a measured example at three settings.
Lossless vs lossy compression for images explained
Lossless compression restores every pixel; lossy compression throws detail away for a smaller file. See real test figures and when each approach is right.
PNG to PDF: what really happens to your images
Turn PNG screenshots and graphics into one PDF in your browser. Myths about lossless quality, transparency and file size, checked against a small test.
PNG vs JPG: which should you use?
PNG keeps every pixel and supports transparency; JPG discards detail to stay small. See a side-by-side table and a simple rule for picking the right one.
SVG vs PNG: vector or pixels for logos and icons?
SVG scales to any size because it stores shapes, not pixels; PNG stores pixels and suits screenshots and complex images. Answers to the questions people ask.
WebP to PNG: keep transparency, expect bigger files
Convert WebP to PNG in your browser and keep transparency. Includes a decision flow, what PNG cannot restore, and measured size changes on test images.
WebP vs JPEG: which should you choose?
WebP vs JPEG compared: file size claims from Google's own study and their limits, transparency, browser support, and the cases where JPEG still wins.
WebP vs PNG: a decision flow for choosing
WebP can be smaller than PNG and keeps transparency, but PNG opens everywhere. Follow a short decision flow to choose the right format for each image.
What is a GIF? Colours, animation and why it lasts
GIF stores up to 256 colours per image and can hold simple animations. Learn how it works, its limits, and when a video or a newer format is the better choice.
What is a PDF? Origins, uses and limits
PDF explained: who created it, how it became an ISO standard, what it is good for, how accessibility and passwords work, and what it is not.
What is AVIF? Strengths, support and caveats
AVIF stores images using the AV1 video codec, with transparency, HDR and strong compression. Check where it works, where it does not and what fallback to keep.
What is HEIC? The iPhone photo format explained
HEIC is a HEIF image file that uses HEVC compression, the default iPhone photo format. Learn how it differs from JPEG, why it fails to open and what to do.
What is JPEG (JPG)? How lossy compression works
JPEG and JPG are the same format: a lossy way to store photographs. See how it works, what quality settings do and what artefacts and repeated saving mean.
What is PNG? History, transparency and limits
PNG is a lossless image format with transparency, built as a patent-free replacement for GIF. Learn how it works, its bit depths, and when to avoid it.
What is SVG? Vector images explained
SVG describes pictures as shapes in text rather than pixels, so they stay sharp at any size. See how it works, where it fails and when to export a PNG instead.
What is WebP and when should you use it?
WebP is an image format from Google that handles lossy, lossless, transparency and animation. Here is what it does, where it works and when to avoid it.
Why is my PNG so big? Causes and ways to shrink it
A PNG can be huge because of photo content, high colour depth, pixel dimensions or metadata. Work through this checklist to find the cause and shrink it.