The three costs that get left out
People price a build as hardware plus drives and then treat everything afterwards as free. Three things are missing from that, and together they usually dominate the comparison.
The first is electricity, because the machine is on all the time. At 55 watts idle it consumes about 482 kilowatt-hours a year doing nothing much, and at the rate on your own bill that is a real recurring number. This is why idle draw matters far more than peak draw for a machine like this: the peak happens for an hour or two a day and the idle happens for the rest of it.
The second is drive replacement. A set of drives bought at the same time tends to reach the end of its usefulness at the same time, so it is a sinking fund rather than a one-off. Whether you set the money aside monthly or find it in a lump on the day it is needed, the cost is the same and it recurs. The calculator treats it as an annual amortisation and also drops the whole replacement into the cumulative curve on the month it lands, because that is what the bank balance actually experiences.
The third is your own time, and it is the one people are most reluctant to price. Ten hours a year is modest for a machine that needs updates, occasional attention and the odd unscheduled Sunday. The field defaults to zero so you can leave it out deliberately rather than by accident, and if this is a business where those hours would otherwise be billable, leaving it at zero is not honest accounting.
Reading the break-even properly
The comparison this page makes is a cash one: a large payment now against a small payment every month. The break-even is the month at which the subscription has cost more in total than the build, and it is sensitive to two inputs above all others. One is the monthly fee, which should be the price for the capacity you would genuinely need rather than an entry tier. The other is the recurring cost of running your own, since it is the gap between the fee and that recurring figure which pays down the capital.
Where the break-even lands after the hardware life you entered, the build has not paid for itself before you expected to replace it. That is worth seeing plainly, and it is not the end of the argument. Capacity you control, a restore that runs at local speed rather than over the internet, and not depending on a service continuing to exist at that price are all real, and none of them appear anywhere in this arithmetic.
| Cost | Owned | Subscribed |
|---|---|---|
| Up front | Hardware and the first set of drives | None |
| Recurring | Electricity, and your hours | The monthly fee |
| Periodic | Drive replacement, hardware replacement | Whatever the fee changes to |
| To get data out | Time, at local speed | Time, plus any retrieval charge |
| When it fails | Yours to fix, on your schedule | Theirs, on theirs |
The comparison is not like for like
It is worth being blunt about this because the arithmetic hides it. A machine in your own house and a copy held elsewhere are not the same product. The one in the house is fast, under your control, and shares a building with everything it protects, so a fire, a flood, a theft or an encryption event reaches both at once. The one held elsewhere survives all of those and is slow to get back from, and its price can change.
Which is why the common answer is not either but both, with different jobs: local for speed and for the everyday restore, remote for the bad day. That changes the sum on this page from a comparison into an addition, and it is a better sum. What a copy has to satisfy to genuinely count as offsite is in the cloud backup guide, and how long a restore from each would take is on the backup window calculator.
Capacity is not the same as usable capacity
The capacity field asks for usable terabytes because that is what a subscription quote is for, and the gap between what you buy and what you can use is large. Redundancy takes whole drives, drives are sold in decimal terabytes while most systems report the roughly nine percent smaller binary units, and the filesystem takes its own share on top. Six drives at 12 TB priced here as six drives is 72 TB of purchase and considerably less of usable space; the storage array capacity calculator works out which figure to put in.
Getting this wrong distorts the per-terabyte comparison badly in favour of the build, because it prices the purchase against a capacity that does not exist. The per-terabyte-per-month line on both sides is the honest comparison when the two options are not the same size.
What else the machine costs
A few things sit outside this calculation and are worth remembering before treating its output as complete. The machine makes heat, which in a small room or a closet is a real consideration and is worked through on the case airflow calculator. It wants protection from power interruptions if the data matters, which the UPS sizing calculator sizes and which is a cost as well as a component. And an always-on machine adds to a bill that is easier to attack from the other end: the appliance running cost calculator and the home energy audit guide both deal with the same kilowatt-hours from a different direction.
Questions people ask
How much does a home server actually cost to run?
Work it out from a measured idle draw rather than a label, because idle is where an always-on machine spends nearly all its life. Multiply watts by 24, by 365, divide by a thousand for kilowatt-hours, then multiply by the all-in rate on your own bill including delivery charges rather than the headline energy rate. A machine idling at 55 watts is about 482 kilowatt-hours a year, and at 16 cents that is roughly 77 dollars before you count the hours it spends under load. A plug meter costs very little and turns this from an estimate into a measurement.
Should I count my own time in the comparison?
If the hours would otherwise be spent earning, yes, and leaving them out is how self-hosting comes to look cheaper than it is. If the hours are ones you would happily spend anyway because you find it interesting, then pricing them at zero is a reasonable statement of your own preferences rather than an accounting error. The field defaults to zero so that the choice is deliberate. For a business the answer is straightforward: those hours have a rate and they are not free.
Why does the break-even move so much when I change the monthly fee?
Because the fee is the entire source of the saving. The capital cost is paid down by the difference between the subscription fee and what running your own actually costs each month, so if the fee is 120 dollars and self-hosting costs 7 a month to run, each month closes 113 dollars of the gap. Halve the fee and the same capital takes more than twice as long to recover, since the running cost does not halve with it. This is also why entering an entry-tier price for capacity you would not actually get is the single easiest way to make this page produce a misleading answer.
Is buying drives all at once a mistake?
It is convenient and it means the set ages together, which the sinking fund on this page assumes. A set bought at the same time tends to want replacing at the same time, which produces one large expense rather than a spread of small ones, and the same batch also shares whatever characteristics that batch has. Staggering purchases spreads both the money and the ageing, at the cost of more transactions and possibly higher prices per drive. Neither is wrong; what matters is budgeting for the replacement as a recurring cost rather than being surprised by it.
Does self-hosting replace a cloud backup?
No, and treating it as a replacement is the expensive mistake in this whole subject. A machine in your house shares a building with the data it protects, so anything that reaches the building reaches both copies at once: fire, flood, theft, and ransomware that can see mapped drives. A copy held elsewhere survives those and is slow to restore from. They are different protections against different failures, which is why the usual arrangement is both, with the local copy doing the everyday restores fast and the remote one existing for the day the building is the problem.