How Much Does It Cost to Run a NAS? Calculate Your Annual Electricity Bill

Your NAS runs 24/7, and every watt it draws adds to your electricity bill. The quick answer: a typical 4-bay NAS with 4 HDDs costs roughly $50–$150 per year to run, depending on your local electricity rate and hardware efficiency. This guide walks you through the exact formula to estimate your own NAS’s running cost, explains how drive count and CPU choice change the number, and points you to our interactive NAS Power Cost Calculator to get a precise annual estimate in seconds.

How to Calculate NAS Electricity Cost: The Simple Formula

The math is straightforward once you know your NAS’s power draw. Use this formula:

For example, a NAS drawing 40 watts 24/7 at $0.12/kWh: (40 × 24 × 365) ÷ 1000 × 0.12 = $42.05 per year. That’s roughly $3.50 per month — less than a streaming subscription.

To get started, you need two numbers: your NAS’s average power draw (in watts) and your local electricity rate (in $/kWh). If you don’t have a power meter, use the typical ranges in the next section as a starting point, then plug them into our How Much Storage Do You Need for a NAS? A Practical Sizing Guide to match your hardware to your storage needs before calculating cost.

Typical NAS Power Draw: Idle vs. Load Wattage Ranges

NAS power consumption varies dramatically between idle and active states. Most consumer NAS units spend 80–90% of their time at idle or near-idle, so idle wattage is the key number for annual cost estimates.

How Drive Count and CPU Choice Change the Estimate

Two factors dominate your NAS’s power budget: the CPU and the hard drives. A low-power Intel N100 draws about 6W at idle, while a Xeon E-2300 series can pull 35–50W at idle — a difference of $25–$50 per year at typical US rates.

Hard drives add cost linearly. Each spinning 3.5″ HDD adds roughly 5–7W during reads/writes and 3–5W at idle. If you run 8 drives instead of 4, expect an additional $20–$40 per year in electricity, depending on your rate. SSDs are far more efficient: a SATA SSD draws 0.5–2W at idle, making them ideal for low-power builds.

If you’re choosing a CPU, check our Best CPU for TrueNAS in 2026: From Basic NAS to ZFS Powerhouse guide for wattage comparisons across different TDP classes. The difference between a 15W TDP CPU and a 65W TDP CPU can mean $30–$60 per year in electricity alone.

Regional Electricity Rate Variation: Why You Need Your Own Rate

Electricity rates vary wildly by location. The US average is about $0.12/kWh, but Hawaii averages $0.33/kWh while Louisiana averages $0.08/kWh. That same 40W NAS costs $42/year in Louisiana but $173/year in Hawaii — a 4x difference.

Here’s how the same NAS (40W idle) costs across different regions:

If you’re comparing TrueNAS vs Unraid: Which Should You Run in 2026?, note that TrueNAS ZFS tends to keep drives spinning more often than Unraid’s spin-down-friendly array, which can add $10–$20 per year in higher-rate regions.

Use the NAS Power Cost Calculator for an Exact Number

Manual math works for a rough estimate, but our interactive NAS Power Cost Calculator handles the details: enter your NAS’s idle and load wattage, your local rate, and how many hours per day it’s under load. The calculator accounts for mixed usage patterns — for example, a NAS that idles 20 hours per day and runs at full load 4 hours per day — and gives you an annual and monthly cost.

To use it, you’ll need:

• Your NAS’s idle power draw (check the manufacturer specs or use a Kill-A-Watt meter)
• Your load power draw (if you know it — typically 1.5–2x idle for consumer units)
• Your local electricity rate per kWh (from your bill)
• Estimated hours per day under load (be honest — most NAS units are idle 90%+ of the time)

The calculator also factors in drive spin-down savings if your NAS supports it. For a deeper look at reducing your NAS’s power draw before calculating, read our How to Reduce Your NAS’s Power Consumption (Without Losing Performance) guide.

Bottom Line: Which NAS Running Cost Should You Expect?

For most home users with a 4-bay consumer NAS running 24/7, expect an annual electricity cost of $30–$80 at typical US rates. If you’re building a high-power DIY server with 8+ drives, budget $80–$150 per year. Low-power builds (mini PC + 2 SSDs) can cost as little as $8–$15 per year.

Your exact number depends on three variables: hardware efficiency, drive count, and local electricity rate. Use our NAS Power Cost Calculator to get your personalized estimate — it takes 30 seconds and eliminates the guesswork. Once you have your cost, check whether your NAS’s power draw justifies upgrading to more efficient components, or if you’re better off investing in RAID 1 vs RAID 5: Which Gives You More Usable Storage? for better capacity-per-watt.