Check a file's size and format before you change anything
Before shrinking, converting or re-sending a file, find out two facts: how big it is, and what format it really is. This method shows where to read those facts on Android and on Windows, explains the common formats in plain words, and only then changes anything.
Reviewed 9 Nov 2026
Who it suits
- A website, form or email has refused your file for its size or its format
- You are not sure whether your file is a JPG, a PNG or a PDF
- You want to fix the actual mismatch instead of converting files at random
Who it doesn’t suit
- The file is damaged or will not open at all — size and format checks cannot repair a file
- The receiving service itself is down or your account with it has a different problem
Start guided mode or read all 6 steps below — guided mode is never mandatory.
Before you start
Preparation
- Have the file itself ready on the device you will check it on.
- Find out the limit or required format the service asked for — its upload page or error message usually states both.
▲ Caution — possible effects
- Re-exporting or re-saving an image creates a new file; your original stays unchanged if you save the new one under a new name or in a different place.
- Making an image smaller or converting it can reduce its quality — always check the new copy before sending it.
⬢ Stop if…
- Never rename a file's extension (for example changing .png to .jpg) to make it 'fit'. That changes the label, not the format inside, and usually makes the file unopenable.
- Stop if the site asking for the file is unfamiliar or its demands look suspicious — do not upload personal documents to services you do not trust.
Original sources
- Find & delete files on Android — Android Help (Official documentation — accessed 9 Nov 2026)
- Free up drive space in Windows (finding file sizes in File Explorer) — Microsoft Support (Official documentation — accessed 9 Nov 2026)
- Related free browser-local PDF tools page (Fact Techz) (Official documentation — accessed 9 Nov 2026)
Steps
See the size and format on Android
Open the Files app, find the file, touch and hold it, and open its details or info (often under the three-dot menu). You will see the file's size and its type — also shown by the extension, the letters after the dot in its name, such as .jpg or .pdf.
See the size and format on Windows
In File Explorer, switch the folder to Details view to see a Size column for every file, then right-click the file and open Properties for its exact size and its 'Type of file'. Sorting a folder by size puts the largest files at the top, as Microsoft's storage help describes.
Read the format honestly
The extension is a label for the format inside the file. JPG and PNG are both picture formats: JPG photos are usually smaller, while PNG keeps sharp edges and transparency but is often larger. PDF is a document format that keeps the layout fixed. A service asking for a PDF will not accept a photograph of the document unless it has genuinely been turned into a PDF.
Compare with what was asked
Put the two facts next to the requirement: your file's size against their maximum size, and your file's format against the formats they accept. Only change something if one of these two does not match — changing both 'just in case' wastes effort and can ruin quality.
If an image is too large, re-export a smaller copy
One way: open the photo in your gallery or photo app and look for an edit, export or share option that saves a smaller version; or open it in an image editor and export a copy as JPG with slightly smaller dimensions. Keep the original, and check the copy still looks acceptable before sending it.
If it is a PDF task, use a browser-local PDF tool
For combining, splitting, rotating or lightly compressing a PDF, a related free browser-local PDF tools page is available at fact-techz.pages.dev/pdf-tools, where the file is processed in your own browser rather than uploaded to a server. Afterwards, check the new file's size and format again, and keep your original.
How to check success
Finishing the steps is not the same as fixing the problem. You are done if these practical checks pass:
- Check: Can you state your file's exact size and its format (its extension)?
- Check: Do the size and the format now match what the service asked for?
- Check: Does the new copy open correctly before you send it?
If it fails
- If the format is right and the file is small enough, but one particular device or app still refuses it, the problem may be how that device handles the format. For photos and videos, the related method explains extensions and codecs in plain words. Related method: Understand a media file's format before converting it ›
- If you cannot make the file small enough without ruining it, ask the receiver whether they accept a link to the file in cloud storage instead of an attachment — many services do.
Evidence, review and results
- Source
- Official documentation
- Testing
- Not team-tested
- Reports
- No reviewed results yet — be the first to record yours.
An official source means the maker documents this procedure — it does not mean our team has run it, and one person’s success is not a guarantee for everyone. Public counts appear only when reviewed reports exist; none are published yet.
Record your result
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About this method
Change note: First published version. Where one team did the writing, reviewing and (when done) testing, the same name appears in each role — we say so rather than invent separate people.