Choose the exact file you intend to send
Start with the saved copy, not a preview inside an editor. An export setting describes what you asked an application to create; the saved file is the result that matters. Select that result in the inspector and compare its name with the attachment you intend to submit.
Downloads can contain several versions with suffixes such as copy, compressed or a number. Check the folder and modification time if the names are similar. A correct size measurement of an old attempt will not tell you whether the latest copy fits.
The basic inspector is intended for supported images and PDFs and has a 25 MiB input cap. For a larger file or a different kind of material, your device's file information can provide its storage size without requiring this browser workflow to process it.
Bytes are the underlying measurement
The browser provides a file size in bytes. KB and MB are easier ways to display that number, but the conversion convention matters. Decimal kilobytes and megabytes use powers of 1,000. Binary kibibytes and mebibytes use powers of 1,024. Interfaces do not always label this distinction clearly.
Make My Files Work's current display and maximum-MB control use the binary calculation. One unit in that MB field represents 1,048,576 bytes. The display rounds the result for readability; the comparison uses the stored byte count and the calculated limit. It does not compare only the rounded text on screen.
If a receiving service states an exact byte allowance, use that as the authority. A decimal 2 MB cap is 2,000,000 bytes, while 2 MiB is 2,097,152 bytes. A file between those values can satisfy one interpretation and fail the other. This arithmetic is why apparently similar labels can disagree.
Enter a limit only when you know what it means
Read the instructions beside the destination's upload field. Check whether the figure applies to each attachment or to the combined submission. This inspector evaluates the chosen file against the maximum you supply; it does not automatically discover the recipient's rules.
Leave an unknown limit blank rather than making up a value. You will still obtain file facts, but a compatibility verdict without the destination's requirements is incomplete. A file that is small in general can still exceed a particularly restrictive form.
The current input checks a maximum, not a minimum byte count. If a portal requires a range, check the lower bound independently. Exact thresholds expressed in bytes may need careful conversion before entering the MB value; where possible, keep sufficient headroom that rounding is not the deciding factor.
Read file size separately from image dimensions
A 1200 × 800 photograph and another picture at the same dimensions can have different byte sizes. The format, content and encoding affect storage. Dimensions describe the pixel grid, while file size describes how much encoded data is saved. Neither measurement can stand in for the other.
A small preview on a web page may still represent a large original. Likewise, a heavily compressed image may have large dimensions but poor detail. Use the dimensions checker when a form specifies width or height, and inspect quality with your eyes.
PDF page size is another separate property. An A4 PDF is not inherently smaller in bytes than a Letter PDF, and a long text document may occupy less storage than one scanned colour page. If the form mentions pages or paper dimensions, use the appropriate PDF check.
Why your device and a website may disagree
Besides unit conventions, displays can round to different decimal places. A label that looks exactly on the limit may represent a value slightly above it. Inspect the actual file information when a strict boundary matters rather than relying on the icon label in a file picker.
A device may also show size on disk, which concerns allocated storage space rather than just the file's logical byte length. Upload limits normally concern the data being sent, so do not substitute a disk-allocation figure for the attachment's size.
An upload request can include more than the file itself. Several attachments, other form data and request packaging may be counted by a receiving server. A local per-file check cannot measure that website's full request. If the file fits but a 413 error remains, investigate the request limit separately.
Use the result to choose a sensible next step
If the file is already comfortably below the stated cap, do not compress it merely because an upload failed. Check format, image dimensions, document protection or the current session. Unnecessary reduction can lower quality without addressing the real rejection.
If an image is too large, consider whether its dimensions exceed what the destination requires. A supported smaller export may help. For a PDF, the available compressor attempts lossless repacking; it does not promise a large reduction in scanned pages.
If a target is unreachable without losing information, ask the recipient about an approved alternative. Splitting a document is useful only if separate files are permitted. Renaming the file changes neither its stored size nor the information it contains.
Recheck the downloaded output
Compression and conversion create a different file, so inspect that output rather than assuming it meets the target. A conversion can sometimes increase storage. Select the download, review the measured comparison and open it to check that the contents remain complete.
Keep the original while you review. For a document, inspect small text, signatures and page order. For a photograph, check clarity and orientation. A lower byte count is not a sufficient result if important details are missing or unreadable.
When the output fits, return to the destination and choose that exact copy. Clear an earlier selected attachment if necessary. Keep any confirmation from the receiving service; the file size checker measures a property and does not submit the document on your behalf.
Questions that come up
Does checking size upload my file?
The inspector reads the selected file in your browser and does not transfer its contents to our server. Returning to another website and submitting it there is a separate action under that service's own handling rules.
Can the checker tell me how long the upload will take?
File size is only one factor. Connection performance, the receiving server and the site's processing also matter. This checker does not test that transfer path or promise an upload duration.
Why is zero bytes a problem?
A zero-byte file contains no data to submit. It may be an empty placeholder or a failed export. Return to the source and save or download a complete copy rather than trying to compress the empty file.