Cloud vs On-Prem Storage Cost
Find the month a NAS stops costing more than a cloud subscription.
What you provide
A four-bay NAS with spinning disks idles around 30 to 50 W.
Result
The NAS pays for itself after 38 months
Over five years the box costs $2,226 against $2,880 for the subscription. Cost is only half of the decision. A NAS in your house is not an offsite backup: a fire, a flood or a theft takes the original and the copy together, and so does ransomware that reaches a mapped drive. The arrangement most people end up wanting is the box for fast local restores and a cheap cloud tier for the copy that lives somewhere else.
- NAS up frontEnclosure plus 4 drives
- $1,100
- NAS running costElectricity plus drive replacement set aside
- $18.77 / month
- Cloud8 TB at $6.00 per TB
- $48.00 / month
- Break-even
- 38 months
- Five years, NAS
- $2,226
- Five years, cloud
- $2,880
What this cannot tell you
- Cost arithmetic on the figures you enter. It does not check any provider price list and it cannot know what your data is worth.
- It compares money, not safety. A box in your house and a copy in a data centre survive completely different disasters, and that difference is usually more important than the break-even month.
Take this with you
How this calculation works
The comparison most people run puts the price of a box against a monthly subscription and stops there, which flatters the box. This one keeps the running costs in: electricity for every hour of every year, and a monthly amount set aside for the drives, which are consumables rather than a one-off purchase. Those running costs are subtracted from the subscription before the crossover is worked out, so the break-even month reflects what owning hardware actually costs rather than only what it costs to buy.
What the results mean
- NAS running cost
- Electricity plus a monthly sinking fund for drive replacement. This is the number that gets left out of most comparisons, and at low capacities it can be most of the subscription price.
- Break-even
- The month the total spent on the box passes the total spent on the subscription. Beyond three years, treat it with suspicion, since hardware and cloud prices both move.
- Five years, NAS
- Purchase plus sixty months of running costs. Five years is roughly the service life of consumer drives, so it is a fair window for the comparison.
Common problems and fixes
- The break-even says never, but a NAS still feels cheaper
- That usually means the capacity is small enough that the subscription is genuinely competitive, or the electricity price is high. Check the power figure. A four-bay NAS with spinning disks that never sleep can cost more per year to run than a terabyte of cloud storage, and low-power flash or aggressive disk spin-down changes the picture significantly.
- The cloud price per TB looks nothing like what providers advertise
- Consumer sync services and cold archive tiers are priced very differently, and both are sold by the terabyte. Archive storage is cheap per month but charges to retrieve, sometimes heavily, and can impose a minimum storage duration. Price the tier you would genuinely use for the access pattern you genuinely have.
Frequently asked questions
Is a NAS a backup?
No. A NAS is storage, and RAID inside it is availability rather than backup. It protects against a drive dying and does nothing about a deleted file, a bad sync, ransomware reaching a mapped drive, or the building it sits in flooding. A backup is a separate copy, ideally one that is offsite and that your live machines cannot write over.
What usually works out best in practice?
Both, in a specific arrangement. The box gives fast local restores over your own network, and a cheap cloud tier holds the copy that survives the house. Most people arrive here after buying one and discovering it does not do the job of the other.
Should I count my own time?
If you are honest, yes. Firmware updates, a failed drive to swap, and the afternoon a volume will not mount are real costs that a subscription does not have. They are hard to price, which is why this calculator leaves them out, but they belong in the decision.
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