File size checker with extension rules
Use the file size checker to check selected files against a maximum size, allowed filename extensions, or both. Download a report showing which files pass your criteria. Free to use, with no sign-up required.
Files processed on your deviceFiles are read in this tab only. Nothing is uploaded.
01 How it works
- Choose one or more files.
- Set a maximum size, allowed extensions, or both.
- Download the JSON or CSV report.
02 Good to know
Size limits use MiB units (1 MiB = 1,048,576 bytes). Extension checks use filenames and do not inspect file contents. Choose at least one criterion. The selection is limited to 1,000 files and 1 GiB total.
03Set file size and extension rules
Choose files, then set at least one check: a maximum size, one or more allowed extensions, or both. The report marks each selected file against the criteria you entered and can be downloaded as JSON or CSV.
Size limits use MiB, where 1 MiB equals 1,048,576 bytes. Extension checks read the filename suffix. They do not inspect file contents or confirm that the file format matches its extension.
04Use the results as a selection check
This is useful when preparing files for a form, handoff, or upload with stated size and naming requirements. Compare the report with the recipient's actual requirements before sending; the tool does not know rules that you have not entered.
A file can pass an extension check while containing different data than the suffix suggests. Use a format validator when the file's internal structure must be verified.
05What gets checked
Only the files you select are checked. This tool does not inspect your folders or device. The selection limit is 1,000 files and 1 GiB total.
06 Questions
What does the extension check verify?
It compares the filename extension with the extensions you allow. It does not read file contents to certify the format.
What unit does the maximum size use?
MiB. One MiB is 1,048,576 bytes.
Can I check only a maximum size?
Yes. Set a maximum size, allowed extensions, or both. At least one criterion is required.
Can I download the results?
Yes. The report is available as JSON or CSV.