electronics · 8W typical
Running a external hard drive costs about $0.95/month.
That's the typical external hard drive at 8W, run 24 hours a day at the US-average rate of 16.5¢/kWh. Change any of those and the number moves — use the calculator below to see yours.
Estimated cost
Full-power draw for 24 hours at 16.5¢/kWh.
How you use it
Cost shifts with how long it's on.
The same external hard drive can cost very different amounts depending on usage patterns. Three common scenarios, at the US-average rate.
always-plugged backup
$0.95
per month
continuous backup target
occasional use
$0.08
per month
mount when needed
Where you live
$1.72 spread between the cheapest and priciest states.
Same appliance, same hours of use, different zip code — the monthly cost varies this much.
| State | Rate | Monthly | Yearly |
|---|---|---|---|
| Hawaii | 41.2¢ | $2.37 | $28.87 |
| California | 31.4¢ | $1.81 | $22.01 |
| Massachusetts | 30.8¢ | $1.77 | $21.58 |
| Connecticut | 28.7¢ | $1.65 | $20.11 |
| Rhode Island | 27.9¢ | $1.61 | $19.55 |
| New Hampshire | 24.6¢ | $1.42 | $17.24 |
| Alaska | 24.3¢ | $1.40 | $17.03 |
| New York | 22.3¢ | $1.28 | $15.63 |
| Maine | 22.1¢ | $1.27 | $15.49 |
| Vermont | 21.5¢ | $1.24 | $15.07 |
| Michigan | 19.3¢ | $1.11 | $13.53 |
| New Jersey | 19.1¢ | $1.10 | $13.39 |
| Maryland | 18.4¢ | $1.06 | $12.89 |
| Pennsylvania | 18.1¢ | $1.04 | $12.68 |
| District of Columbia | 17.8¢ | $1.03 | $12.47 |
| Wisconsin | 17.4¢ | $1.00 | $12.19 |
| Delaware | 17.2¢ | $0.99 | $12.05 |
| Illinois | 16.9¢ | $0.97 | $11.84 |
| Ohio | 16.6¢ | $0.96 | $11.63 |
| Nevada | 16.3¢ | $0.94 | $11.42 |
| Indiana | 15.8¢ | $0.91 | $11.07 |
| Virginia | 15.7¢ | $0.90 | $11.00 |
| Minnesota | 15.6¢ | $0.90 | $10.93 |
| Colorado | 15.4¢ | $0.89 | $10.79 |
| Alabama | 15.2¢ | $0.88 | $10.65 |
| West Virginia | 15.2¢ | $0.88 | $10.65 |
| Florida | 15.1¢ | $0.87 | $10.58 |
| New Mexico | 14.8¢ | $0.85 | $10.37 |
| Texas | 14.8¢ | $0.85 | $10.37 |
| Arizona | 14.7¢ | $0.85 | $10.30 |
| South Carolina | 14.7¢ | $0.85 | $10.30 |
| Kansas | 14.6¢ | $0.84 | $10.23 |
| Georgia | 14.2¢ | $0.82 | $9.95 |
| Iowa | 14.1¢ | $0.81 | $9.88 |
| North Carolina | 13.9¢ | $0.80 | $9.74 |
| Missouri | 13.6¢ | $0.78 | $9.53 |
| Oregon | 13.4¢ | $0.77 | $9.39 |
| Tennessee | 13.3¢ | $0.77 | $9.32 |
| Kentucky | 13.2¢ | $0.76 | $9.25 |
| Mississippi | 13.1¢ | $0.75 | $9.18 |
| Oklahoma | 13.1¢ | $0.75 | $9.18 |
| South Dakota | 12.7¢ | $0.73 | $8.90 |
| Montana | 12.4¢ | $0.71 | $8.69 |
| Nebraska | 12.2¢ | $0.70 | $8.55 |
| Arkansas | 12.1¢ | $0.70 | $8.48 |
| Washington | 12.1¢ | $0.70 | $8.48 |
| Louisiana | 11.9¢ | $0.69 | $8.34 |
| Wyoming | 11.6¢ | $0.67 | $8.13 |
| North Dakota | 11.5¢ | $0.66 | $8.06 |
| Utah | 11.4¢ | $0.66 | $7.99 |
| Idaho | 11.3¢ | $0.65 | $7.92 |
Efficient vs. inefficient
A $18.79/year difference across the wattage range.
Swapping a high-draw model for an efficient one pays for itself. Here's what that looks like annually at typical usage.
Most efficient
2W
$0.24 per month
$2.89 per year
Typical
8W
$0.95 per month
$11.56 per year
High draw
15W
$1.78 per month
$21.68 per year
When it hits hardest
year-round peak
Constant backup use.
Ways to cut the cost
- 1
Use SSD for always-plugged drives — 75% less watts than HDD
Saves 30-50 kWh/year
- 2
Only plug in during backup windows
Cuts runtime 80%+
- 3
Enable drive spin-down after 15 min idle
HDDs draw ~half when parked
Real-world wattages
Pulled from actual spec sheets.
| Brand | Model | Watts |
|---|---|---|
| Western Digital | My Book 8TB | 10W |
| Seagate | Backup Plus 5TB | 8W |
| Samsung | T7 Portable SSD 2TB | 2W |
Picks that actually move the needle
Three products worth comparing if you're thinking about upgrading or supplementing what you have.
Some links below are affiliate links. If you buy, we may earn a small commission — it never changes the price you pay, and we only recommend picks we would stand behind.
See also
Related appliances
Sources: www.energy.gov · www.energystar.gov
Last updated: 2026-04-13