NAS, RAID and Backup Storage
Hard drive cost per TB calculator.
The real cost of a hard drive is its price plus the electricity it uses while running. A $250, 12 TB drive that draws 6 W for 5 years at $0.15 per kWh uses 262.8 kWh worth $39.42, for $289.42 in total, or $24.12 per TB and $4.82 per TB per year. Runs in your browser; nothing is sent or stored.
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Worked example
One $250, 12 TB drive that averages 6 W, runs 24 hours a day for 5 years at $0.15 per kWh. Energy = 0.006 kW x 8,760 h x 5 years = 262.8 kWh x $0.15 = $39.42. Total = $250 + $39.42 = $289.42, which is $24.12 per TB and $4.82 per TB per year. Electricity is 13.6% of the total.
How it works
Energy cost = watts / 1,000 x hours per day x 365 x years x price per kWh x drives. Total cost = drives x price + energy cost. Cost per TB = total / raw TB, and per TB per year divides that by the years of service.
The tool uses only the numbers you enter: it assumes no drive prices, wattage or electricity rates. Spin-down, idle versus active power and shorter run hours all change the energy line; enter an average. To turn raw TB into usable TB for your RAID level, use the RAID calculator; to cost any other device see the appliance electricity cost 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):
- RAID (Wikipedia): Background on drives, arrays and redundancy; the cost model here is arithmetic on your own price, wattage and electricity rate.
FAQ
How much does it cost to run a hard drive 24/7?
Watts / 1,000 x 8,760 hours x your price per kWh. A 6 W drive uses 52.56 kWh a year, which is $7.88 a year at $0.15 per kWh.
What is a good cost per TB for a hard drive?
There is no fixed figure because prices change. Use this tool to compare any two drives on the same basis: total cost per TB over the years you will run them.
Does a bigger drive save money overall?
Often yes per TB, because the fixed power and bay cost is spread over more capacity. Enter two drives and compare their cost per TB per year.
How do I find my drive wattage?
Check the datasheet for idle and active power, or measure with a plug-in power meter. Use an average that reflects how much the drive sits idle.
Should I count RAID overhead?
If you want cost per usable TB, divide the total by the usable TB from the RAID calculator rather than the raw TB.