NAS, RAID and Backup Storage
Backup window calculator.
Backup time is data size divided by effective bandwidth: 500 GB over a 1,000 Mbps link at 70% efficiency is 700 Mbps, which takes about 1 hour 35 minutes. Enter the data size, the link speed and how much of it you really get, plus an optional window to see what fits. Runs in your browser; nothing is sent or stored.
Your backup
Backup time
Fill the form and press Calculate.
Worked example
500 GB over a 1,000 Mbps link where you get 70% of the speed: 1,000 x 0.70 = 700 Mbps = 87.5 MB/s. 500 GB x 8 = 4,000 gigabits, and 4,000,000 megabits / 700 Mbps = 5,714 seconds = 1 h 35 min. In a 2 hour window you can move at most 630 GB, so this backup fits.
How it works
Time = data x 8 bits per byte / (link speed x efficiency). With decimal units, 1 GB is 8,000 megabits. The efficiency figure is your own assumption, since the real rate depends on the slowest part of the chain: source disk, network, protocol, encryption and the destination.
Backups are usually much smaller after the first full run, so size the window for your incremental data too. Plan how big each run is with the 3-2-1 backup storage calculator. For a general download estimate see the game download time calculator.
Estimates only. RAID is not a backup: it keeps an array running through a drive failure but does not protect against deletion, malware, fire or theft. Real arrays and drives vary, so use this for planning and check your own drive datasheets.
Sources and basis (opened 2026-10-08):
- Data Backup Options (CISA, Ruggiero and Heckathorn): Backup methods and copies; the transfer-time division on this page is plain arithmetic on the numbers you enter, and no link speeds or efficiencies are assumed.
FAQ
How long will my backup take?
Divide the data in bits by your effective speed. 500 GB at an effective 700 Mbps takes 5,714 seconds, about 1 hour 35 minutes.
What efficiency should I use?
Measure it. Copy a large file and compare the speed to the link speed. 70% is only a starting assumption; overhead, disk speed and shared traffic all change it.
How much data fits in my backup window?
Effective speed x window length. At 700 Mbps a 2 hour window moves about 630 GB.
Why is my first backup so slow?
The first run copies everything. Later runs copy only changes, so they are usually far smaller and fit the window more easily.
Does this work for cloud uploads?
Yes. Enter your upload speed as the link speed. Home internet upload speeds are often much lower than download speeds, which makes cloud seeding slow.