5 checks before sending large files: compression, time and sharing
When an upload fails or a transfer takes too long, check size limits, compression, expected time, sharing method and the received file in order.
Sending a large file takes more than pressing Send. Destination limits, upload speed, available apps and the information inside the file affect the workflow. Zipping an already compressed video may barely reduce its size, and a completed transfer does not prove the result opens correctly. Use these five checks and follow the relevant existing tools.
Check real size and destination limits
Read the actual file size and distinguish a per-file limit from the total upload allowance. MB and MiB can represent different byte counts. Renaming an extension does not convert the file or reduce its size.
For several files, collect only the needed copies and check names and count. Review personal information, internal documents and photo location metadata. Establish what you may share and with whom before optimising size.
Decide whether compression will help
Archiving documents or many small files with 7-Zip can be convenient. JPEG, MP 4 and existing ZIP files may shrink little because they are already compressed. Re-encoding video and creating an archive have different quality and compatibility effects.
Choose a format the recipient can open, then inspect the archive and test extraction. Plan password delivery if used; a lost password can be hard to recover. Keep originals until you have checked that nothing was omitted.
Estimate time with matching units
Use the transfer-time calculator with file size and expected speed. Mbps usually means megabits per second; MB/s means megabytes per second. They differ by eight bits per byte. Separate upload and download speed measurements.
Actual time depends on sender upload, recipient download, service limits, Wi-Fi and other traffic. An efficiency setting is your assumption, not a universal network average. Allow time for retries and recipient confirmation before a deadline.
Choose local or remote sharing
For devices on the same local network, consider LocalSend and check both devices, apps and network requirements. If discovery fails, follow official permission guidance rather than disabling the entire firewall. People on another network need a remote method.
For remote services such as Wormhole, read current size, expiry and download conditions. A link can contain access information: check the recipient and keep it out of public posts. Encryption claims do not guarantee anonymity or safety in every context. Expiring links are not long-term backups.
Open the received file and compare hashes if needed
The recipient should check count, names and sizes, extract archives and open the files in their actual applications. For video, check picture and sound at the beginning, middle and end. A completion message alone will not catch an incomplete file or wrong version.
If exact identity matters, compare SHA-256 values calculated before sending and after receiving. A mismatch warrants checking file, version and transfer. Matching hashes confirm matching bytes, not sender identity or absence of malware. Exchange the comparison value through a trusted channel.
Keep originals and work with a delivery copy. Confirm that the recipient opened the file before tidying temporary links and retained material. An estimated time, actual completion, matching bytes and file safety are separate checks.
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Sources
Based on public documentation; not a full functional or security audit.