How Much Online Backup Space Will I Need?

Will I need just a few GB or should I get an unlimited plan?

Image of a large man vs a small man on a seesaw
Gary Waters / Getty Images

Every plan by every online backup service seems to offer a completely different amount of backup space - some offer just a few GB while others offer thousands... or more! How in the world do you decide how much backup space to buy?

The following question is one of many you'll find in our Online Backup FAQ:

"How do I figure out how much online backup space I'm going to need?"

Once you've determined what you need to back up (see What Exactly Should I Back Up? for help with that), calculate the space that data is using and make sure that whatever online backup plan you're looking at has enough storage for that amount of data.

It would also be wise to estimate what you expect to add to your important data in the future. Calculating your future needs is more of an art than a science so some educated guessing is certainly expected here.

For example, if you're planning to back up everything currently stored on your external hard drive, which is used exclusively for movies and music, first check how much storage space is being occupied on it right now. Then, if you consider that you'll download one new song every day (assuming they're around 4 MB each), and a video every month (5 GB per video), you can guess that you'd need around 1.5 GB every year for music and an additional 60 GB for movies.

Screenshot of a hard drive's used space in Windows 8
Checking a Hard Drive's Used Space (Windows 8).

In this example, if your external HDD is already using 100 GB, and you plan to add, at a minimum, around 60 GB more per year, you not only need a plan that supports 100 GB for what you have now but one that's big enough to hold what you expect to add later. Five years down the road, with this particular setup, you'll be needing 400 GB of total backup space.

Another way to better visualize how much space you might need in the future is to look at how quickly you've already filled up your hard drive(s) in the last few months or years. If you keep buying 4 GB flash drives every few months because you're running out of space, pretend its all online storage space and do the math to calculate what that would equate to for online storage, and then look for a relevant plan.

Considering the difficulty in knowing how much backup space you might need someday, it would be wise to at least be aware of an online backup service's policies and prices regarding storage overage. Most online backup provider's plans are tiered and they'll contact you with an opportunity to upgrade as the backup space you're using approaches their next tier. You can also usually upgrade your plan yourself any time you think you'll need more space in the future.

Screenshot of the MiMedia backup upgrade options
MiMedia's Upgrade Options.

Another option is to just go with the service's smallest tier and then upgrade as you go, should you need to. You might find that their lowest storage plan is all you need, or that you only need to upgrade to the next higher tier to fulfill your needs instead of start off with the biggest plan available.

If you're still not sure how much space you might need then consider a cloud backup plan with unlimited space. These plans are rarely much more expensive, if at all, than space-limited plans and you won't have to worry about uploading more than your allotment. See our Unlimited Online Backup Plans for a ranked list of these types of plans.

On the other hand, if you find out that your most important files take up less than a few GB, consider one of the many backup providers that offer feature rich but completely free plans. See our Free Online Backup Plans for a list of those, ranked by the amount of free space they offer.

Other Online Backup FAQs

Here are a few more questions that I'm often asked during the search for the right backup service:

Here are more questions I answer as part of our Online Backup FAQ: