Well after launch, Samsung started offering increased storage options for the Galaxy S9 and S9+, giving buyers the choice of 128 or 256GB in addition to the default 64GB it sold for several weeks after launch. If you haven't yet bought a Galaxy S9 or S9+, it's absolutely worth exploring which storage option is right for you. Here's what you need to consider.
Internal storage is not the same as SD card storage
You may be saying to yourself, "why would I buy more internal storage when I have an SD card slot?" Great question, and here's the answer: your microSD card is not treated the same as internal storage. This is because Samsung still uses SD cards as removable storage rather than adoptable storage, meaning the card is treated as a separate volume. That has all sorts of benefits, like allowing you to remove the card without disrupting the phone's operation, but also has downsides.
SD cards are great for mass storage of data, but not necessarily for data you need to access quickly and reliably. You can store pictures, videos, music and movies on your SD card, but things like apps and sensitive data can only be placed on internal storage. Large chunks of data can't span across internal and external storage, either — they have to be stored entirely on one or the other.
Having an SD card slot in your Galaxy S9 or S9+ gives you lots of options for upgrading your storage after purchase, but isn't a one-to-one replacement for buying more storage from the start.
Where you buy the phone matters
Higher storage options for the Galaxy S9 and S9+ are only available online, from Samsung, as unlocked models. That means you won't be able to head to Amazon, Best Buy or your carrier and get a GS9 with 256GB of storage — annoying, but it's the reality we're dealing with.
Buying an unlocked phone from Samsung in itself isn't a problem at all — in fact it's preferable in almost every way. The unlocked phones from Samsung work on all major U.S. carriers, but are free from the bloatware and annoying software changes that you'll so often find on carrier models.
Going this route is only a problem if you're trying to take advantage of carrier incentives on your Galaxy S9 or S9+ purchase. Having more storage is awesome, but if Verizon is offering a BOGO deal or Sprint has a big discount on its lease program, those savings may outweigh the benefit of the extra storage for you.
Pick a storage size
Alright, so you've determined that you're okay buying the phone from Samsung, and you know that an SD card is not a direct replacement for internal storage — now, which storage size should you buy? The best way to start off here is to say "buy as much as you want to pay for." That is, if you have the extra $100 and plan to use your Galaxy S9 or S9+ for a long time, buy the 256GB model. You'll never regret having more storage, especially if $100 (or about $4 more per month when financed) isn't that big of a deal to you at the start.
On the other hand, most people who don't know how much storage they'll need will be completely happy paying just $50 more to have the peace of mind that 128GB of storage brings. You probably won't ever be pushing up against the 64GB barrier on the base model, but having 64GB more room beyond that is simply nice to have and doesn't cost that much extra. And you're far less likely to hit any sort of nagging "storage full" message when you go to install a hot new game or record a bunch of 4K video a year from now.
And finally, if you've never had a phone with over 32GB of storage and haven't been close to filling up those smaller storage sizes, you're going to be fine just getting the default 64GB model and saving some money. Put some of it toward a good case or some other top-notch accessories instead.
If you're thinking about buying that 256GB model, think about doing it sooner rather than later — Samsung has a $20 discount on the top storage options of both the Galaxy S9 and S9+ until May 17. After that, the prices will be $839 and $959, respectively.
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Andrew was an Executive Editor, U.S. at Android Central between 2012 and 2020.