Buying based on size alone usually leads to one of two problems: you either overspend on massive capacity you won’t use for a decade, or you underbuy and find yourself shopping for more storage in less than a year.
Measuring by time converts raw drive capacity into a timeframe based on how quickly you fill it. The basic idea is simple: divide your free storage capacity by your total average usage per month.
It is every bit as simple as it sounds, but in many ways, it is a nicer way to shop for storage.
Buy for time, not purely on volume
Your consumption over time is probably stable
Personal data growth is generally pretty predictable, whether you’re talking about your personal PC or your homelab setup. Your photo habits, the resolution of your videos, and the number of devices in your home don’t swing wildly week to week or month to month.
Take Immich as an example. When I was planning my current backup system for Immich, I determined that each photo took up around 16MB (which is below average for RAW+JPG), so I get about 62 pictures per gigabyte or 62,500 pictures per terabyte. Our phone libraries grow at knowable, consistent rates. When I started considering it that way, it wasn’t “I have 4TB free still” it was “I can take another 250,000 pictures.” Since I can also know how many pictures I average over a month (about 500), I know that 4TB will last me decades more at my present consumption rate.
The same is true of most things I self-host, not just image storage. Videos—which are enormous by comparison—also grow at a pretty predictable rate. The game servers that I host for my friends and me are on rigid backup schedules. My music media server adds a few CDs a month (normally). My utility apps (like network monitors) don’t generate very much data I need to store for a prolonged period, but what information they do produce is very consistent.
Other popular services, like Nextcloud and Paperless, also tend to be used consistently, especially if they’re a big part of your homelab. That means their data use will be consistent too.
- Storage Capacity
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2 – 26TB
- Workload
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550TB/yr
- Suitable for
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NAS
Western Digital’s Red Pro NAS hard drives come in sizes from 2TB to 26TB.
Buying by years means you don’t over or under spend
The fact that most things consume data at a predictable rate makes shopping for components (and upgrades) easier.
It means that I can appropriately factor in the cost of storage for my photos whenever I build (or rebuild) my home server. I can put away a little bit of money each month specifically based on what I expect to need in 5 years and time my upgrades to get the best deals on storage.
I started estimating my yearly data storage needs about 10 years ago when I started “seriously” self-hosting, and I haven’t over or underspent on storage for my homelab in that time. On the other hand, I have pretty egregiously overspent on the storage I have available in my desktop PC, and I don’t forecast my data needs.
I’d recommend calculating your storage needs in a 3–5 year rolling window. That is a normal range for drive warranties; they’re not likely to wear out from use, and you probably won’t need to upgrade the rest of your system in that time frame either.
How to figure out your own data growth rate
Actually measure it if you can
To get an accurate number, you need to track your real usage for a few months rather than just guess. If you’re considering switching to a self-hosted photo solution, you can quickly eyeball the number of pictures taken in a month or in a year in your Photos app. If you’re already self-hosting your photos, you can often pull that data directly from the service. Immich, for instance, shows library size and counts. Then multiply whatever that number is by the average size of a photo and video.
If you’re trying to figure it out for other self-hosted services, you could set up a simple disk-usage script on a cron job to record your filesystem size monthly. Compare the amount of data stored at the beginning and then at the end, and you have your data growth rate.
When you calculate your usage, make sure you give yourself some margin. The initial import is always going to be huge, and you should assume that you’re going to have big weeks—like on a vacation or at a wedding—that consume an order of magnitude more data than your average.
Additionally, you can and should estimate device upgrades, too, especially if your storage gear is on a 5-year or longer upgrade cycle. Phone cameras are always getting better. Today my phone records in 4K at 60FPS. In 24 months, my new phone may be recording 4K at 120FPS or 8K at 60FPS.
Buying on a schedule makes it easy to deal hunt
Shifting your perspective to years-based planning replaces guessing or impulse buying with a more informed approach.
You get predictable spending, and you eliminate those last-minute “the drive is full” emergencies that force you into last-minute, very expensive decisions. Start logging your monthly storage use now; it’ll turn your next big drive purchase into a more informed, cost-effective affair.
Stephan is the sports journalist for the Maple Grove Report.
