First ask yourself what you plan on backing up. The overwhelming majority of people will be backing up digital photos, personal videos, music files and of course 007 top secret documents, spreadsheets and presentations. However, you could be using it for your business which could theoretically need more storage space. You should go to each individual folder, right click on it and click on ‘properties.’ A box will pop up telling you how much space is being occupied by that specific folder. Go through each important folder on your computer and add up all the storage numbers from each folder. If you reach, say, 50GB in storage from your important files, you should generally find a plan with 2 or 3 times that amount of storage. If you research your options by reading online backup provider reviews, you’ll notice that many companies offer unlimited storage. If you’re unsure what your data needs will be in the future, it’s recommended to purchase a plan from a provider that will allow you to upgrade to an unlimited storage plan should you need it in the future.