Formats, file sizes, and settings worth knowing before you use a tool.
12 guides
Not sure what quality number to use when compressing photos? See measured sizes at quality 75 and 60, when resizing beats lowering quality, and PNG tips.
A checklist for combining PDFs before you submit them: the recipient's file rules, password-protected files, what merging drops, page order and file names.
Three ways to turn iPhone HEIC photos into JPG: switch the camera to Most Compatible, convert as you move photos to a computer, or convert in your browser.
No-upload tools run in your browser with WebAssembly, Web Workers and WebCodecs. See what the page loads, what it never sends, and how to check.
Compare JPG, PNG, WebP and AVIF on compression, transparency and browser support, and see which format fits photos, logos, web images and iPhone photos.
MOV and MP4 are containers, and both can hold H.264 or HEVC video. See how they differ, when a MOV becomes MP4 without re-encoding, and when to re-encode.
128, 192 and 320kbps set how much data each second of an MP3 uses. See how to work out file size, what MDN recommends, and when to keep the original audio.
Match a photo to an online form's pixel, file size and format rules: what to check in the instructions, when not to edit, and why to resize first.
Combine phone photos of receipts and paperwork into one PDF, one photo per page: shooting tips, paper size, orientation, margins, HEIC and file size.
Save only the pages you need from a PDF as a new file. Choose one file or one per range, write ranges like 1-3, 5, 8-, and see how the results are named.
Video too big to send? Check the attachment limit first, then lower the resolution and bitrate to save a smaller MP4. See what each quality level does.
A GIF's size grows with its frame count and the pixels in each frame. See how fps, width, clip length and dithering affect it, with measured examples.