Cloud vs Local Storage Cost Calculator
Cloud storage is rent; buying drives is a purchase. Enter the terabytes you need and how long you plan to keep them, pick a cloud plan, and I will price the drives from live Amazon.com listings, add the power they draw, and show the exact point where owning the data becomes cheaper than paying the cloud forever. Still sizing the array? Start with the NAS storage calculator , then come back here to decide cloud versus local.
Your assumptions
Only the drive cost is a live HDDHunt figure: the typical (25th-percentile) price of a trustworthy internal 3.5″ HDD at the cheapest whole-drive capacity tier on Amazon.com, the same number behind the cheapest $/TB ranking. The cloud rate, the electricity rate and the ~15 W base + 8 W-per-drive power model are editable assumptions, not scraped prices. Cloud tiers and hardware move around, so plug in your own. The model leaves out one-time enclosure hardware and any cloud egress or restore fees; add those to the numbers above if they apply to you. Links are affiliate links, disclosure.
Not sure how many terabytes you actually need first? The NAS Storage Calculator sizes the array from your Plex library, photos and backups, and the RAID Calculator turns a drive count into usable capacity and fault tolerance.
Why owning storage usually wins
The two ways to keep terabytes have completely different cost shapes. A cloud subscription is a flat monthly rent that never ends: at a typical object-storage rate of around $6 per TB per month, 8 TB costs roughly $576 every year, and you pay it again next year, and the year after. Buying hard drives is a single upfront cost (the same 8 TB is a one-time purchase), after which the only ongoing expense is the handful of dollars of electricity to keep the drives spinning.
Because the cloud bill accumulates and the purchase does not, the cloud always overtakes local ownership eventually. The only real question is when, and that depends on today's drive prices, your capacity and your cloud rate. This tool answers it precisely: the local side is priced from the same live price index that powers the cheapest $/TB ranking, using the typical (25th-percentile) price of a trustworthy internal 3.5-inch hard drive at the cheapest whole-drive capacity tier, never a single floor listing.
What the cloud does buy you is somebody else's redundancy, offsite safety and zero maintenance, which is why the calculator lets you mirror the local side to two copies for a fairer fight, and why the honest answer for a true 3-2-1 backup is often both: bulk drives at home for the working copy, and a cheap cloud tier for the one offsite copy you would cry without. If you are pricing a real array rather than a flat two-copy mirror, the RAID calculator works out the usable capacity and build cost for RAID 5, 6 and 10 first.
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