Just keep in mind that these basic plans tend to have several drawbacks, like file size limits and restrictions on the number of devices you can include.
Winner: free cloud-based solutions
The Basic Backup: 20 to 100GB
You're a simple user with simple storage needs. It's just that you've got 40,000 family photos and a temperamental desktop that might crash any day. Unfortunately, the 20 to 100GB range is a bit awkward, with few free solution — and upcharges for those extra gigs.
External hard drives aren't an attractive option. A 100GB drive will end up costing you between $1 and $4 a gig — highway robbery these days.
Instead, snap up a low-cost cloud plan like hubiC, Box Starter, or OpenDrive Home.
Winner: cheap cloud-based solutions
The Standard Backup: 100 to 500GB
Today's average consumer will likely need storage somewhere in this range, enough for a small family or one HD movie enthusiast.
Here, the median cost for an online service per gig (per year) is 42 cents, compared to 41 cents for an external hard drive — virtually dead even. Consider, however, that 90 percent of external hard drives will last for three years without failure. (After that, the chance of failure roughly doubles, year after year.) So if you assume a responsible hard drive owner will replace the drive once every three years, it's only fair to compare that 41 cents for the external drive to $1.26 (42 cents x 3) for three years of a cloud-based service.
Yes, there's a 10 percent chance your external hard drive will fail in those first three years, so a cautious consumer might consider the extra 82 cents an insurance policy. But for those willing to take the risk, an external drive is more cost-effective for backups in this range.
Winner: the external hard drive
The Big Backup: 500 GBs to 1TB
Here, things get a little closer. Based on our data, three years of an online service in this range will cost you about 36 cents per gig, while three years of an external hard drive will clock in at about 21 cents per gig. The math says an external drive is the right choice here, but that insurance policy is suddenly only 15 cents.
Winner: we'll call this one a draw.
The Big Backup: 1TB+
Beyond one terabyte, the decision becomes easy again. External hard drives in this range are certainly efficient (only about 12 cents per gig, on average), but cloud-based plans are even better. Once you hit a full terabyte, the incremental cost of more space becomes less and less of a factor. For three years of storage, you'll pay only about 4 cents per gig for an online plan.
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