HDD vs SSD NAS Running Cost Calculator: What's the Real Electricity Difference?

This calculator compares what hard drives and SATA SSDs cost to buy and to run in a NAS over 1 to 10 years. It uses the data sheet power figures for each drive's part number, the hours a day your drives spend active, idle and spun down, an Australian electricity rate by state or your own, and NTK's current market prices or yours.

An SSD draws far less than a hard drive only when it can drop into its low power state, which depends on your NAS. Drive prices move, so the answer moves too: the calculator works out the break-even from today's figures, and only when both sides hold the same raw capacity.

Hard drives

Drive

Number of hard drives

Price per hard drive

SSDs

SSD

Number of SSDs

Price per SSD

My NAS enables SATA link power management (DIPM) for SSDs

Hours a day: active, idle, spun down

Starting profiles to edit, not measurements. If your NAS reports how long its drives spend spun down, use that.

Comparison period

Your state (electricity rate)

Electricity rate (c/kWh)

Enter your setup above to see the running cost.

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Hard drives: electricity a year

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SSDs: electricity a year

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Running cost difference

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Break-even

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	Hard drives	SSDs
Raw capacity
Drive cost
Electricity ()
Total
Per TB: drives + electricity

Power used

Not in the money

This compares drive prices and electricity only. Noise, speed, heat and how much you write to the drives are separate questions it does not price.

Worked Example: Equal Capacity

4 x Seagate IronWolf 4TB (ST4000VN006) against 4 x Samsung 870 EVO 4TB: both hold 16 TB raw. Moderate profile: 6 hours active, 13.2 idle and 4.8 spun down a day.

Hard drives: (4.8 W x 6 h + 3.96 W x 13.2 h + 0.5 W x 4.8 h) x 365 days x 4 = 121.9 kWh a year.
SSDs without DIPM (idle hours at the 2.5 W writing figure, an NTK planning figure because Samsung publishes no idle figure without DIPM): 87.6 kWh a year.
SSDs with DIPM (idle hours at 0.035 W): 22.8 kWh a year.
Seagate IronWolf 4TB: NTK market price $352 (2026-10-23). Samsung 870 EVO 4TB: NTK market price $1,999.

What these drives cost to run, and whether the SSDs pay back, depends on your electricity rate and today's prices, so the calculator works it out: open this example in the calculator, or with DIPM, then pick your state or enter your rate.

How We Calculate

Energy per drive. (Operating W x active hours + idle W x idle hours + spun down W x spun down hours) x 365 days, divided by 1,000 for kWh. A year is 8,760 hours.

SSDs do not spin down, so their idle and spun down hours are all idle hours. An SSD's data sheet idle figure is often published only with SATA link power management (DIPM) on. Unless you tick DIPM, NTK counts those hours at the SSD's writing figure. That is an NTK planning figure, not a published one: the data sheet gives no idle figure without DIPM, so the real draw is not known. With DIPM ticked it uses the data sheet low power figure and shows its condition.

Cost = drives x kWh per drive x your rate. Totals = drive prices + electricity over the period. Break-even = the SSDs' extra upfront cost divided by the yearly running cost they save, with four cases: they pay back after N years, they are ahead from day one, the hard drives catch up after N years, or they never pay back. A break-even and a verdict are given only when both sides hold the same raw capacity; otherwise compare the per TB figures.

Prices are NTK's market price for the drive (the median across at least three Australian retailers with fresh listings), or the price you enter. A drive without a current market price needs your price before its totals and break-even appear.

Drive power figures

Drive	Part number	Operating W	Idle W	Spun down or low power W	Source
Seagate IronWolf 4TB	ST4000VN006	4.8	3.96	0.5	Seagate data sheet, checked 2026-10-07
Seagate IronWolf 8TB (ST8000VN002)	ST8000VN002	5.3	4.0	0.25	Seagate data sheet, checked 2026-10-07
Seagate IronWolf 8TB (ST8000VN004)	ST8000VN004	10.1	7.8	1.0	Seagate data sheet, checked 2026-10-07
Seagate IronWolf 12TB	ST12000VN0008	7.3	5.1	1.17	Seagate data sheet, checked 2026-10-07
WD Red Plus 4TB (WD40EFPX)	WD40EFPX	4.7	3.1	0.3	Western Digital data sheet, checked 2026-10-07
WD Red Plus 4TB (WD40EFZZ)	WD40EFZZ	4.5	2.9	0.3	Western Digital data sheet, checked 2026-10-07
WD Red Plus 8TB	WD80EFPX	5.2	3.4	0.4	Western Digital data sheet, checked 2026-10-07
WD Red Pro 12TB	WD122KFBX	8.8	6.1	0.3	Western Digital data sheet, checked 2026-10-07
Samsung 870 EVO 1TB	MZ-77E1T0	2.5 average write (the higher of read 2.0 / write 2.5 W)	not published without DIPM	0.03 Idle, DIPM on	Samsung data sheet, checked 2026-10-14
Samsung 870 EVO 2TB	MZ-77E2T0	2.5 average write (read 2.2 / write 2.5 W)	not published without DIPM	0.035 Idle, DIPM on	Samsung data sheet, checked 2026-10-14
Samsung 870 EVO 4TB	MZ-77E4T0	2.5 average write (read 2.2 / write 2.5 W)	not published without DIPM	0.035 Idle, DIPM on	Samsung data sheet, checked 2026-10-14

Samsung data sheet: idle with DIPM (device initiated power management) on; measured with IOmeter on a desktop PC. Applies only if the NAS enables SATA link power management.

Where one part number's figures differ from another sold under the same name (Seagate IronWolf 8TB ST8000VN004 and ST8000VN002, WD Red Plus 4TB WD40EFPX and WD40EFZZ), each part number is listed separately. Check the part number on your listing.

Electricity rates used

State	Rate (c/kWh)	What it is	Date
NSW	33.96	Australian Energy Regulator: default market offer (DMO), price cap on standing offers. AER DMO 8 Final Determination 26 May 2026, Section 9(1), avg of 3 NSW zones	September 2026
VIC	28.2	Essential Services Commission: Victorian Default Offer (VDO). ESC Victorian Default Offer 2026-27 domestic flat tariff, avg of 5 distribution zones	September 2026
QLD	27.97	Australian Energy Regulator: default market offer (DMO), South East Queensland only. AER DMO 8 Final Determination 26 May 2026, Section 9(1), Energex flat rate (SE Queensland)	September 2026
SA	41.91	Australian Energy Regulator: default market offer (DMO), price cap on standing offers. AER DMO 8 Final Determination 26 May 2026, Section 9(1) SA Power Networks flat rate	September 2026
WA	33.26	WA State Government (Energy Policy WA): regulated tariff (Synergy, set in the State Budget). Synergy Home Plan (A1) from 1 Jul 2026 (WA Government-set tariff)	September 2026
TAS	24.75	Office of the Tasmanian Economic Regulator: regulated standing offer (Aurora Energy, maximum price). Aurora Energy Tariff 32 Residential Single Rate from 1 Jul 2026 (OTTER-approved standing offer)	September 2026
ACT	36.95	Independent Competition and Regulatory Commission: regulated standing offer (ActewAGL Retail). ActewAGL ACT Standard plan from 1 Jul 2026 (ICRC standing offer), Home all usage	September 2026
NT	31.68	NT Government Electricity Pricing Order (enforced by the Utilities Commission): regulated retail price (Electricity Pricing Order). Jacana Energy regulated residential tariff from 1 Jul 2026	September 2026

Enter the rate from your bill for your own figure; on a time of use plan, use your average (blended) rate.

Assumptions NTK made

Method last reviewed: 2026-10-14. Drive figures last checked at source: 2026-10-07. Market prices: 2026-10-23. Electricity rates dated from: 2026-09-25.

Frequently Asked Questions

Do SSDs use less power than HDDs in a NAS?

Usually, but the gap depends on the drive and on whether your NAS lets SSDs use their low power state. The hard drives on this page list 4.5 to 10.1 W operating and 2.9 to 7.8 W idle on their data sheets. Samsung lists the 870 EVO at 2.5 W writing and 0.035 W idle, but only with SATA link power management (DIPM) on. For four Seagate IronWolf 4TB drives against four Samsung 870 EVO 4TB drives at the Moderate profile, the hard drives use 121.9 kWh a year and the SSDs 87.6 kWh with their idle hours counted at the writing figure (Samsung publishes no idle figure without DIPM), or 22.8 kWh with DIPM.

Do SSDs ever pay back their price in electricity?

It depends on today's drive prices and your rate, so the calculator works it out instead of assuming an answer. There are four cases: the SSDs cost more to buy and less to run, so they pay back after some years; they cost less to buy and less to run, so they are ahead from day one; they cost less to buy but more to run, so the hard drives catch up after some years; or they cost more to buy and more to run, so they never pay back. The calculator only gives a break-even when both sides hold the same raw capacity. A payback can fall far beyond a usual comparison period when the SSDs cost much more to buy and save only a little in electricity each year, and the calculator says when a payback falls beyond the period you chose. Enter your drives, prices and rate to see yours.

What is DIPM, and why does the SSD figure change with it?

Device initiated power management (DIPM) lets a SATA SSD drop its link into a low power state when it is idle. Samsung publishes the 870 EVO idle figure (0.035 W) only with DIPM on. Whether a NAS enables SATA link power management depends on the NAS and its settings, so NTK does not assume it: by default the calculator counts idle hours at the SSD's writing figure. That is an NTK planning figure: Samsung publishes no idle figure without DIPM, so the real draw is not known. The DIPM figure is used only when you tick the box.

Why is there no break-even when the capacities differ?

Four 8TB hard drives and four 4TB SSDs do not store the same amount, so a cheaper total for one side would not be a like for like answer. When the raw capacities differ, the calculator shows the cost per TB for each side and leaves out the break-even and the verdict. Change the drive counts or sizes so both sides hold the same raw capacity.

Which Australian state has the highest running cost?

Of the regulated and reference rates on this page, SA is the highest at 41.91 c/kWh and TAS the lowest at 24.75 c/kWh (September 2026), so the same drives cost 69% more to run in SA. Your own retailer's rate matters more: enter it from your bill.

Does this calculator say whether I should use SSDs?

No. It compares money only: drive prices and electricity. Noise, speed, heat and how much you write to the drives are separate questions it does not price.