The Galaxy S21 FE arrived almost a year after the S21 and confused the lineup. It is not a shrunken S21 Plus and it is not a stretched S21 — it sits between the two with dimensions of its own, and Samsung changed the camera housing material at the same time. If you own one and are shopping from a generic "S21 series" listing, you will end up with the wrong shell.
Three phones, three sizes
- Galaxy S21 (SM-G991): 6.2-inch display, 151.7 x 71.2 x 7.9 mm, 169 g, 4,000 mAh
- Galaxy S21 FE 5G (SM-G990): 6.4-inch display, 155.7 x 74.5 x 7.9 mm, 177 g, 4,500 mAh
- Galaxy S21 Plus (SM-G996): 6.7-inch display, 161.5 x 75.6 x 7.8 mm, 200 g, 4,800 mAh
The FE is 4 mm taller and 3.3 mm wider than the base S21. That is comfortably enough to prevent an S21 case from closing around it, and enough that an S21 in an FE case will shift under its own weight.
The camera housing is the other difference
On the base S21 and S21 Plus, Samsung wrapped the camera housing into the aluminium frame so it flows off the left edge of the phone. On the S21 FE the camera module is moulded plastic in the same colour as the back panel, and it does not blend into the frame the same way. It also protrudes less.
That matters for cases in a specific way: a case cut for the S21's contour-cut housing has a cutout that runs right to the edge of the frame. On an FE that cutout would leave the top-left corner of the phone unsupported, which is the corner most likely to take a drop.
Cases for the Galaxy S21 FE
The FE is the value model in the family and a lot of them are still in service as secondary or work phones. That is exactly the use case where a sealed full-body shell earns its keep — a phone that lives on a jobsite or a boat is going to meet water long before it meets a concrete floor.
If you want to keep it slim and still cover both faces, a magnetic double-sided tempered glass case sandwiches the phone between two panels with an aluminium frame around the edge.
Browse the Galaxy S21 FE Cases collection for cuts made to the 155.7 mm body.
Cases for the base Galaxy S21
At 169 g and 151.7 mm the base S21 is genuinely compact by modern standards, and the people still using one usually chose it for that. A metal case adds structure without much thickness, and the S21's flat display makes edge coverage straightforward.
The Galaxy S21 Cases collection has the full set. The Galaxy S21 Plus Cases collection covers the 161.5 mm model.
Battery is the real issue on these phones now
The S21 shipped with a 4,000 mAh cell and the FE with 4,500 mAh. Lithium-ion cells lose capacity with cycles, and phones from this generation are well past the point where the original figure means much. If your S21 is not making it through a day, a battery case is a cheaper fix than a replacement handset — but battery cases are moulded to a specific chassis and port position, so an S21 pack will not fit an FE.
Screen protectors
Both phones use a flat display, so tempered glass applies cleanly on either. The S21 uses an ultrasonic in-display fingerprint reader; the S21 FE uses an ultrasonic reader as well. In both cases pick glass that names fingerprint compatibility, and re-register your fingerprint after applying it — that single step fixes most "my reader stopped working" complaints.
Sheet sizes differ between the two models. A 6.2-inch cut on a 6.4-inch panel leaves an unprotected strip at the top and bottom.
Frequently asked questions
Will an S21 Plus case fit an S21 FE? No. The Plus is 161.5 x 75.6 mm against the FE's 155.7 x 74.5 mm — nearly 6 mm taller, and with the contour-cut camera housing the FE does not have.
Will an S20 FE case fit an S21 FE? No. The S20 FE is 159.8 x 74.5 x 8.4 mm. Same width, but 4 mm taller and half a millimetre thicker, with a different camera block.
Do the S21 and S21 FE use the same charger? Both use USB-C. The S21 supports up to 25 W wired, the FE up to 25 W as well, so a single 25 W brick covers both.
Does either have built-in magnets for MagSafe-style accessories? No. Any magnetic mounting on these phones comes from the case, not the phone.
How do I confirm which one I have? Settings > About phone > Model number. SM-G991 is the S21, SM-G990 is the FE, SM-G996 is the Plus, SM-G998 is the Ultra. Questions on a specific cut can go through the Contact page or 978-797-0223.
The bottom line
The S21 FE is its own phone with its own dimensions and its own camera housing. Nothing that touches the body — case, glass, holster, battery pack — crosses over from the S21 or S21 Plus. Chargers and universal mounts do.