Practical file preparation guides

When you convert a file, the conversion tool reads the source file, interprets its structure and content, and then writes that content into the rules of the target format. The original file is not altered — the converter creates a new file in the chosen format.

Not all formats store information the same way. A PDF can contain fixed layout with embedded fonts. A DOCX file stores styled paragraphs in XML markup. When you convert between them, the tool tries to translate one set of rules into another — and some details inevitably get approximated or lost.

Elements that commonly change during conversion include page margins and spacing, fonts (especially if the target format doesn't support them), image quality, table alignment, and document metadata. For simple documents, conversion usually goes smoothly. For complex layouts — tables within tables, multi-column designs, embedded objects — the output should always be reviewed.

The most reliable habit when converting any file is to keep the original and review the output before relying on it for anything important.

Lossless compression reduces file size without discarding any information. The file is encoded more efficiently so that when it is uncompressed the original data is perfectly restored. PNG images use lossless compression. A compressed PNG will look identical to the original — it is just stored more compactly.

Lossy compression works differently. It permanently removes data that a human is unlikely to notice — smoothing out fine detail in images, for example, or discarding audio frequencies that are difficult to hear. JPEG is a lossy format. Each time a JPEG is re-compressed at a lower quality setting, some detail is permanently gone.

The trade-off is always size versus quality. Moderate compression usually produces an acceptable balance. Very aggressive compression — targeting an extremely small file size — can introduce visible artefacts: blurring on text, banding in gradients, pixellation around edges.

Before compressing any file you want to keep, compress a copy rather than the original, and compare the output at full size. What looks acceptable as a small thumbnail can look obviously degraded at full resolution.

PDF is the most reliable format for sending documents by email. It preserves layout and fonts across all devices and operating systems, does not require the recipient to have a specific application to open it, and is widely accepted by email providers. If you are sending a form, invoice, letter, or report, PDF is almost always the right choice.

For photos and images, JPEG is practical for most purposes. It keeps file sizes manageable and is universally supported. If you need a transparent background — for a logo, for example — PNG is the better option, though PNG files are generally larger than JPEG at equivalent dimensions.

ZIP archives are useful when you need to send multiple files at once or when individual files are close to the size limit. Compressing a batch of images or documents into a single ZIP can significantly reduce total size and simplifies the recipient's download.

Be aware that executables (.exe, .bat), scripts, and certain archive types (.zip files containing executables) are sometimes blocked by mail servers or spam filters. When in doubt, rename or re-archive to ensure delivery. Total attachment limits vary by provider — most allow between 10 MB and 25 MB, but the recipient's mail server may impose tighter limits.

PDF is the format most commonly required by official portals. Government forms, legal submissions, and compliance documents are routinely expected in PDF because it preserves the exact layout and can be digitally signed. If a form asks for a 'scanned document', a PDF of your scan is almost always appropriate.

For identity documents and photographs, JPEG is usually specified. Portrait photos for visa applications, for example, often come with precise resolution requirements (such as 600×600 pixels) and maximum file sizes. It is worth reading the platform's requirements carefully — a photo that is even slightly outside the specified dimensions can cause an automated rejection.

PNG is sometimes requested for documents that contain text or line art, where the sharpness of lossless compression is preferred over JPEG's smoothing. Some platforms also accept TIFF for scanned documents, though this is less common in consumer portals.

FormatOS can help you hit specific format requirements — converting documents to PDF, resizing images to required pixel dimensions, or compressing files below a maximum size threshold. However, each platform sets its own rules, and meeting those rules is the responsibility of the person submitting.

WebP is a modern image format designed specifically for the web. It typically produces smaller file sizes than JPEG and PNG at comparable visual quality, which means pages load faster for visitors. Most modern browsers — Chrome, Firefox, Safari, Edge — support WebP. If your website builder or CMS accepts WebP, it is a practical choice for photographs and graphics.

JPEG remains a solid choice for photographs where transparency is not needed and the image will be displayed at a fixed size. Compressing a JPEG to 70–80% quality usually provides a good balance between visual fidelity and file size without introducing obvious artefacts.

PNG is the better option when you need a transparent background — for logos, icons, or interface elements that sit on top of other content. PNG files tend to be larger than JPEG, so it is worth sizing them to the exact pixel dimensions they will be displayed at rather than relying on HTML/CSS to scale them down.

SVG is the right choice for logos, icons, and simple illustrations. Because SVG is a vector format rather than a pixel grid, it scales to any size without becoming blurry, and the file size is typically very small. FormatOS includes an SVG-to-PNG converter for cases where a rasterised version is needed.

In photographs taken with a smartphone or camera, metadata typically includes the date and time the photo was taken, the device model, and often GPS coordinates. This means that a photo of your home, shared online or sent to a stranger, may include the precise location where it was taken — even if the image itself gives nothing away.

Office documents — Word files, PDFs, spreadsheets — can carry metadata such as the author's name, the organisation the software is registered to, revision history, comments, and the dates the file was created and last edited. This information may be visible to anyone who receives the file.

Metadata removal tools strip out the most commonly recorded fields. FormatOS includes metadata removal for images (EXIF/IPTC data) and PDFs. These tools reduce the most obvious identifiers — but metadata can be complex. Some formats store information in multiple locations, and some applications re-add metadata when a file is saved.

For most everyday file sharing, built-in metadata removal is sufficient. If you are handling genuinely sensitive files — legal documents, photos with location data, or materials where identifying details could cause harm — verify the output carefully and consider using a specialist tool in addition to a general-purpose converter.

If a file is legally or professionally significant — a signed contract, a certified translation, a court submission, a medical record — converting it can alter the layout or formatting in ways that affect its meaning or validity. A converted document may look similar but contain subtle differences in spacing, line breaks, or typography that matter in a formal context. Always verify legal or official documents before submitting a converted version.

Password-protected or encrypted files are another case where caution applies. FormatOS does not unlock or decrypt protected files. If you convert a protected PDF, the output may not preserve the original content correctly. Make sure you understand what a file contains and whether protections are in place before attempting a conversion.

Very large or high-resolution files can also be risky to convert without thought. A 200 MB video, a 300 DPI print-ready PDF, or a multi-gigabyte archive may produce unexpected results in a browser-based tool — either failing silently, timing out, or producing a degraded output. For production files at scale, purpose-built desktop software is often a better choice.

Finally, if you are not sure what a file is or where it came from, it is worth understanding it before uploading it anywhere. FormatOS is built for files you own. Uploading files you do not have the rights to use, or files from untrusted sources, is outside the intended use of the service and may expose you to legal risk.

Start with the file type you have, not the outcome you want. FormatOS is built around an upload-first approach: you upload your file, and the workspace shows the actions that genuinely apply to it. This reduces the chance of choosing a tool that is mismatched to the file.

For PDF work, the choice between tools depends on what you are changing: page structure (split, merge, reorder, rotate, extract), page content (add page numbers, watermark), or metadata (remove PDF metadata). Each of these is a distinct operation — doing them all in sequence requires multiple passes.

For images, the distinction between format conversion (JPG to PNG, PNG to WebP), quality adjustments (compression, resize), and metadata handling (EXIF removal) matters. You can chain these — for example, resize first, then convert format, then compress — but the order affects the final quality.

For sending files to other people, the key question is usually format compatibility and file size. Convert to a format the recipient can open without special software (usually PDF for documents, JPEG or PNG for images) and compress if the file exceeds your email provider's attachment limit. A ZIP archive handles multiple files cleanly.