The calculation
A worked example
An 8-hour window at 20 Mbps and 85% efficiency can carry about 61.2 GB, with no reserved traffic.
Start with changed data
A routine incremental backup normally sends new or changed data, not the full size of your disk. Use an observed upload volume from the backup application when possible. Some systems transfer entire changed files, while others transfer blocks; deduplication and compression can reduce traffic, but already-compressed video may shrink little.
Do not confuse a daily job with the first backup
The first seed backup may be many times larger than a typical day. Calculate it separately with the transfer-time tool and keep the device powered and awake. Leave room for scan, encryption, verification and retries. A transfer that barely fits in ideal conditions is not a resilient schedule.
A completed upload is not the whole backup plan
Check retention, version history and your ability to restore. Test a small restore and make sure your recovery credentials are available. This tool evaluates network capacity only; it cannot verify data integrity, backup coverage or a recovery strategy.
Source & further reading
Model reviewed October 25, 2026. Read our methodology and limitations.