21.5-inch iMac 4K vs 27-inch iMac 5K: Which should you buy?

Display size isn't the only thing different between the 27-inch iMac 5K (2020) and 21.5-inch iMac 4K (2019). Internally, they are different beasts entirely. Much of this is because one was just refreshed, and the other has not. It's because of this that we're recommending one model over the other. It's time to take a look at the most current iMacs on the market!

Break it down now

Each year, Apple usually releases new iMacs at the same time. That way, internals between both options are mostly the same. In August 2020, however, only the 27-inch iMac received an update. The 21.5-inch iMac, by contrast, was last refreshed in March 2019.

The 17-month time difference between the two release dates means two important things. First, there's no doubt Apple is also about the update the smaller iMac. Second, you should probably hold off on making a new purchase if you have your heart set on a smaller display size. If you want a 27-inch iMac, however, now is the time to buy.

As you can see, there are significant differences between the two iMac models starting with the display size and resolution. All 27-inch iMacs offer a 5K (5120‑by‑2880) resolution with support for one billion colors. All but one of the 21.5-inch models includes a 4K (4096-by-2304) resolution with support for one billion colors. There isn't a 5K model available with a 21.5-inch display.

On the 2020 and larger iMac model, there's also True Tone built into the display. With True Tone (carried over from MacBook and many iPads), the color temperature of the screen automatically adjusts to match a user's ambient lighting.

The newer and larger model also offers an optional nano-texture glass option for the first time. Previously introduced on the Pro Display XDR, nano-texture glass offers even better viewing under various lighting conditions, such as a bright room or indirect sunlight.

Looking inside the iMacs

Looking on the inside, it's clear the larger iMac offers better specs even at the entry-level. Here, you'll find up to a 10th-generation 10-core Intel Core i9 processor and 128GB of RAM. It's also the first iMac with a 1080p FaceTime HD camera.

In terms of storage, Apple is only offering all-flash SSD on the 27-inch model. By contrast, the older 21.5-inch version still provides a 1TB Fusion Drive as an option, besides SSD. With SSD, overall, you get to experience higher capacity and lightning speed. Plus, because SSD means there are no moving parts, making it less like you'll damage your machine. SSD also offers much faster read-write speeds.

Price, not surprisingly, is the one thing the smaller computer has going for it right now. It's much cheaper than the larger model and could soon be more so were it to get discontinued. Still, you can't forget an update is probably coming soon.

Back in June, Apple announced plans to ditch Intel processors for native Silicone over the coming years. The move probably means the current 27-inch iMac is the last to ship with Intel inside. The next 21.5-inch iMac refresh could be one of the first to feature Silicone. However, it's more likely that distinction will come to an upcoming MacBook model first.

If you're a graphics artist or someone who wants the next big thing, go with the iMac (2020) and upgrade it to the spec levels you can afford. No doubt, this will be the best 27-inch Intel-based iMac you'll ever see (and the last for this display size), and it's the one full of new features, standard and optional.

If you're in the market for a smaller iMac, you should wait until the rest of Apple's 2020 plans are revealed. There's nothing wrong with the current 21.5-inch iMac. And yet, it could soon be replaced by something much better in just a few weeks. Therefore, you should wait.