Numbers are tricky. If you look at the spec sheet for the Samsung Galaxy S21 Plus, you'll see a very specific number: 6.7 inches. But honestly, that’s a bit of a marketing half-truth.
Most people buy this phone thinking they’re getting a massive slab of glass, and while it’s definitely not small, the way Samsung measures that s21 plus screen size is based on a "full rectangle." Once you factor in those beautiful, rounded corners and the little punch-hole for the selfie camera, your actual viewable area is slightly less. It’s more like 6.5 inches of usable space.
Does that matter? For most of us, not really. But if you’re trying to fit a specific video crop or you're a hardcore mobile gamer, those missing millimeters in the corners are where your UI elements live.
The Flat Screen Controversy
Remember when every flagship phone had to have those "waterfall" curved edges? The S21 Plus was a bit of a turning point. Samsung ditched the dramatic curves of the S20 series and went with a 6.7-inch Flat FHD+ Dynamic AMOLED 2X panel.
It was a polarizing move. Tech enthusiasts who loved the futuristic look of curved glass felt like it was a downgrade. However, if you've ever tried to find a glass screen protector that actually stays on a curved screen, you know the struggle. The flat display on the S21 Plus basically solved the "accidental palm touch" problem that plagued the Ultra models. It’s practical. It’s rugged. And thanks to the Corning Gorilla Glass Victus, it’s surprisingly hard to scratch, though it'll still shatter if you drop it just right on a sidewalk.
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Why 1080p Was a "Smart" Downgrade
Let’s talk about resolution because this is where the nerd-fights happen. The S21 Plus has a resolution of 2400 x 1080 pixels.
On paper, that looks worse than the S20 Plus, which had a QHD+ display. But here’s the reality: most users never actually turned on the QHD+ mode because it drained the battery like a leaky faucet. By locking the s21 plus screen size to 1080p, Samsung allowed for a much more efficient adaptive 120Hz refresh rate.
- Refresh Rate: It scales from 48Hz to 120Hz.
- Pixel Density: You’re looking at ~394 ppi.
- Brightness: It peaks at 1300 nits, which is plenty for reading a text in direct Texas sunlight.
Unless you’re holding the phone three inches from your eyeballs, you probably can't tell the difference between this and a 4K panel. What you will notice is how smooth the scrolling feels.
Handling the 6.7-inch Form Factor
Is it a "two-hand" phone? Mostly.
The dimensions are roughly 161.5 x 75.6 x 7.8 mm. It’s thin, which helps, but it’s still wide. If you have smaller hands, reaching the top corners is going to be a thumb-stretching exercise. Samsung’s One UI helps by moving most clickable things to the bottom half of the screen, but the physical size is undeniable.
Comparing it to its siblings:
- Galaxy S21: A petite 6.2 inches. Feels like a toy in comparison.
- S21 Plus: The 6.7-inch "sweet spot" for most.
- S21 Ultra: A massive 6.8 inches, but it feels way bigger because of the extra thickness and the curved glass.
The Plus model is sort of the "Goldilocks" version. You get the big-screen experience for Netflix or YouTube without the astronomical price tag or the literal weight of the Ultra. It weighs about 200 grams. That’s roughly the weight of a medium-sized apple, which is light enough to not hurt your pinky finger during a long scrolling session but heavy enough to feel premium.
The "Green Line" Elephant in the Room
We have to talk about the issues. It’s not all sunshine and AMOLED rainbows.
As these phones have aged, some users have reported the dreaded "green line" appearing vertically across the display. This isn't unique to the s21 plus screen size—it’s happened across various OLED panels from multiple brands—but it’s a hardware failure usually triggered by heat or software-induced voltage spikes.
If you see a thin green or pink line, it’s not a software glitch you can "restart" away. It’s a physical failure of the display ribbon. In some regions, like India, Samsung has historically offered one-time free replacements for this specific issue, even out of warranty, but that’s not a global rule. If you're buying one used in 2026, check that screen under a pure white background very carefully.
Repair Costs in 2026
If you do crack that 6.7-inch beauty, be prepared for some sticker shock. Even though the phone is several years old, the Dynamic AMOLED 2X tech is still expensive.
- Official Repair: Expect to pay anywhere from $230 to $300 at an authorized center like uBreakiFix.
- Third-Party: You might find it for $180, but you risk losing the high-quality color calibration or the ultrasonic fingerprint sensor's accuracy.
The fingerprint sensor is actually under the glass. It’s an ultrasonic sensor, which is way faster than the optical ones found in cheaper phones. It uses sound waves to map your print, so if you put a cheap, thick plastic screen protector on it, it might stop working entirely. Stick to the "Loca" glue protectors or very thin films if you want to keep that biometric speed.
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Real-World Usage: Gaming and Media
The s21 plus screen size is basically built for the 20:9 aspect ratio. This is great for modern movies, which are often shot in wide formats. You’ll still get small black bars on the sides of a standard 16:9 YouTube video, but for cinematic content, it fills up almost the entire front of the device.
For gamers, the 120Hz refresh rate is the real hero here. Playing something like Genshin Impact or Call of Duty: Mobile feels incredibly responsive. Because the screen is flat, you don't get that weird color shifting or "glare" on the edges that you get with curved phones. It’s just a consistent, bright image from edge to edge.
Is it Still Worth It?
Honestly, the display on the S21 Plus holds up surprisingly well against the newer S24 or S25 models. Samsung reached a "peak" with their AMOLED technology a few years ago where the improvements became incremental. A few more nits here, a slightly more efficient backplane there, but the core experience remains top-tier.
The 1300 nits of peak brightness is the "real world" metric that matters. You can sit at an outdoor cafe and actually read your emails without squinting. The Eye Comfort Shield also does a decent job of nuking blue light at night without making the screen look like a jar of mustard.
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Actionable Next Steps for S21 Plus Owners
If you're looking to keep your screen in top shape or you're thinking about buying one:
- Check for Burn-in: Go to a blank white webpage. Look at the top (where the clock is) and the bottom (where the nav bar is). If you see ghostly outlines of icons, that's permanent OLED burn-in.
- Enable Adaptive Refresh: Don't lock it to 60Hz to save battery unless you're desperate. The phone is designed to scale down to 48Hz anyway, and the 120Hz is half the reason to own this phone.
- Screen Protector Choice: If you want the fingerprint sensor to work, look for "Made for Samsung" certified protectors. Avoid generic tempered glass that doesn't mention "ultrasonic compatibility."
- Insurance Check: If you're buying used, see if the seller has any remaining Samsung Care+. Screen repairs are the most common expense for this model, and having a deductible is way better than paying $250 out of pocket.
The S21 Plus remains a workhorse because it didn't try to be "extra" like the Ultra. It just provided a massive, flat, high-quality window into your digital life. While the specs say 6.7 inches, the experience is really about that 120Hz smoothness and the punchy colors that Samsung is famous for. Just keep it in a case; glass is still glass, and 6.7 inches is a lot of surface area for gravity to target.