Samsung Galaxy S21 (Korea) is a samsung device (codename: sm-g991n). FirmwareMirror hosts 56 verified firmware builds, covering: KOO, KTC. Available as official firmware. Last updated: January 2026. All files MD5-verified. Free, no registration.
Find and download official Stock ROM for Samsung Galaxy S21 (Korea) (sm-g991n). All firmware files include MD5 hash verification and are available for direct download.
| Version | Method | Size | Release Date | MD5 Hash | Download |
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| G991NKSSCHZA9/G991NOKRCHZA9/G991NKOSCHZA5 | Odin | 562.78 MB | 2026-01-01 |
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| G991NKSS9HYE5/G991NOKR9HYE5/G991NKOS9HYE5 | Odin | 314.69 MB | 2025-05-01 |
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| G991NKSU8HYD9/G991NOKR8HYD9/G991NKOU8HYD9 | Odin | 326.22 MB | 2025-04-01 |
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| G991NKSS8GYC1/G991NOKR8GYC1/G991NKOS8GYC1 | Odin | 3.26 GB | 2025-03-01 |
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| G991NKSS8GYA1/G991NOKR8GYA1/G991NKOS8GYA1 | Odin | 266.31 MB | 2025-01-01 |
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| G991NKSS8GXL1/G991NOKR8GXL1/G991NKOS8GXL1 | Odin | 282.79 MB | 2024-12-01 |
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| G991NKSS8GXK1/G991NOKR8GXK1/G991NKOS8GXK1 | Odin | 318.16 MB | 2024-11-01 |
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| G991NKSS7GXJ1/G991NOKR7GXJ1/G991NKOS7GXJ1 | Odin | 327.93 MB | 2024-10-01 |
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| G991NKSS6GXI2/G991NOKR6GXI2/G991NKOS6GXI2 | Odin | 339.59 MB | 2024-09-01 |
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| G991NKSS6GXG2/G991NOKR6GXG2/G991NKOS6GXG2 | Odin | 348.47 MB | 2024-07-01 |
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| G991NKSS6GXGJ/G991NOKR6GXGJ/G991NKOS6GXGJ | Odin | 343.65 MB | 2024-07-01 |
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| G991NKSSCHZA5/G991NOKRCHZA5/G991NKOSCHZA5 | Odin | 251.31 MB | 2026-01-01 |
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| G991NKSSBHYK5/G991NOKRBHYK5/G991NKOSBHYK5 | Odin | 276.61 MB | 2025-11-01 |
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| G991NKSSAHYH5/G991NOKRAHYH5/G991NKOSAHYH5 | Odin | 299.13 MB | 2025-08-01 |
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| G991NKSS5GXF1/G991NOKR5GXF1/G991NKOS5GXF1 | Odin | 350.69 MB | 2024-06-01 |
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| G991NKSS5GXE1/G991NOKR5GXE1/G991NKOS5GXE1 | Odin | 354.64 MB | 2024-05-01 |
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| G991NKSU4ZWI9/G991NOKR4ZWI9/G991NKOU4FWI8 | Odin | 1.05 GB | 2023-09-01 |
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| G991NKSU4EWE9/G991NOKR4EWE9/G991NKOU4EWE2 | Odin | 1.25 GB | 2023-05-01 |
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| G991NKSU4FWK7/G991NOKR4FWK7/G991NKOU4FWK6 | Odin | 2.13 GB | 2023-11-01 |
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| G991NKSU4EWH5/G991NOKR4EWH5/G991NKOU4EWH5 | Odin | 249.34 MB | 2023-08-01 |
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| G991NKSU4FXD3/G991NOKR4FXD3/G991NKOU4FXD1 | Odin | 2.12 GB | 2024-04-01 |
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| G991NKSS4EWK2/G991NOKR4EWK2/G991NKOU4EWH5 | Odin | 2.29 GB | 2023-11-01 |
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| G991NKSS4FXAD/G991NOKR4FXAD/G991NKOU4FWK6 | Odin | 2.12 GB | 2024-01-01 |
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| G991NKSU4GXDC/G991NOKR4GXDC/G991NKOU4GXDA | Odin | 351.84 MB | 2024-04-01 |
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| G991NKSU4EWCH/G991NOKR4EWCH/G991NKOU4EWCG | Odin | 1.59 GB | 2023-03-01 |
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| G991NKSU3BUK9/G991NOKR3BUK9/G991NKOU3BUK9 | Odin | 2 GB | 2021-11-01 |
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| G991NKSU3AUE8/G991NOKR3AUE8/G991NKOU3AUE6 | Odin | 964.44 MB | 2021-05-01 |
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| G991NKSU3CVH7/G991NOKR3CVH7/G991NKOU3CVH1 | Odin | 218.61 MB | 2022-08-01 |
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| G991NKSU3AUF6/G991NOKR3AUF6/G991NKOU3AUF6 | Odin | 924.59 MB | 2021-06-01 |
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| G991NKSU3CVC5/G991NOKR3CVC5/G991NKOU3CVD1 | Odin | 1.29 GB | 2022-03-01 |
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| G991NKSS3CVI3/G991NOKR3CVI3/G991NKOU3CVH1 | Odin | 2.16 GB | 2022-09-01 |
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| G991NKSU3DVL2/G991NOKR3DVL2/G991NKOU3DVL1 | Odin | 2.07 GB | 2022-12-01 |
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| G991NKSU3BVA2/G991NOKR3BVA2/G991NKOU3BVA1 | Odin | 1.95 GB | 2022-01-01 |
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| G991NKSU3EWB1/G991NOKR3EWB1/G991NKOU3EWA9 | Odin | 1.68 GB | 2023-02-01 |
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| G991NKSU3CVF1/G991NOKR3CVF1/G991NKOU3CVE9 | Odin | 592.51 MB | 2022-06-01 |
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| G991NKSU3CVE1/G991NOKR3CVE1/G991NKOU3CVD9 | Odin | 992.87 MB | 2022-05-01 |
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| G991NKSU3CVEB/G991NOKR3CVEB/G991NKOU3CVE9 | Odin | 595.23 MB | 2022-05-01 |
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| G991NKSU3CVDD/G991NOKR3CVDD/G991NKOU3CVD9 | Odin | 1010.79 MB | 2022-04-01 |
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| G991NKSU3AUDA/G991NOKR3AUDA/G991NKOU3AUD9 | Odin | 1.02 GB | 2021-04-01 |
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| G991NKSU3DVJC/G991NOKR3DVJC/G991NKOU3DVJ8 | Odin | 2.13 GB | 2022-10-01 |
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| G991NKSU3DVKC/G991NOKR3DVKC/G991NKOU3DVK6 | Odin | 2.09 GB | 2022-11-01 |
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| G991NKSU3CVGB/G991NOKR3CVGB/G991NKOU3CVGB | Odin | 549.16 MB | 2022-07-01 |
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| G991NKSS3BULC/G991NOKR3BULC/G991NKOU3BUKF | Odin | 1.98 GB | 2021-12-01 |
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| G991NKSU3BULF/G991NOKR3BULF/G991NKOU3BULG | Odin | 1.95 GB | 2021-12-01 |
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| G991NKSU3BUKG/G991NOKR3BUKG/G991NKOU3BUKF | Odin | 1.98 GB | 2021-11-01 |
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| G991NKSS3AUIN/G991NOKR3AUIN/G991NKOU3AUIG | Odin | 21.83 MB | 2021-09-01 |
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| G991NKSU3AUIG/G991NOKR3AUIG/G991NKOU3AUIG | Odin | 220.87 MB | 2021-09-01 |
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| G991NKSU3AUHB/G991NOKR3AUHB/G991NKOU3AUHB | Odin | 273.87 MB | 2021-08-01 |
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| G991NKSU3AUGM/G991NOKR3AUGM/G991NKOU3AUGA | Odin | 869.69 MB | 2021-07-01 |
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| G991NKSU2AUC8/G991NOKR2AUC8/G991NKOU2AUC8 | Odin | 1.65 GB | 2021-03-01 |
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| G991NKSS2AUBB/G991NOKR2AUBB/G991NKOU2AUBB | Odin | 1.66 GB | 2021-02-01 |
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| G991NKSU1AUB8/G991NOKR1AUB8/G991NKOU1AUB7 | Odin | 1.66 GB | 2021-02-01 |
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| G991NKSU1AUA4/G991NOKR1AUA4/G991NKOU1AUA4 | Odin | 1.68 GB | 2021-01-01 |
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| G991NKSU1AUB2/G991NOKR1AUB2/G991NKOU1AUB1 | Odin | 1.62 GB | 2021-02-01 |
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| G991NKSU1AUAA/G991NOKR1AUAA/G991NKOU1AUAA | Odin | 1.68 GB | 2021-01-01 |
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| G991NKSU1ATLM/G991NOKR1ATLM/G991NKOU1ATLM | Odin | 1.81 GB | N/A |
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Versions: SM-G991B, SM-G991B/DS (International); SM-G991U (USA); SM-G991U1 (USA unlocked); SM-G991W (Canada); SM-G991N (Korea); SM-G9910 (China)
| Network | Technology | GSM / CDMA / HSPA / EVDO / LTE / 5G |
|---|---|---|
| 2G bands | GSM 850 / 900 / 1800 / 1900 | |
| CDMA 800 / 1900 & TD-SCDMA | ||
| 3G bands | HSDPA 850 / 900 / 1700(AWS) / 1900 / 2100 | |
| CDMA2000 1xEV-DO | ||
| 4G bands | 1, 2, 3, 4, 5, 7, 8, 12, 13, 14, 18, 19, 20, 25, 26, 28, 30, 38, 39, 40, 41, 46, 48, 66, 71 - SM-G991U1 | |
| 1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 32, 38, 39, 40, 41, 66 - SM-G991B | ||
| 5G bands | 2, 5, 25, 41, 66, 71, 260, 261 SA/NSA/Sub6/mmWave - SM-G991U1 | |
| 1, 3, 5, 7, 8, 20, 28, 38, 40, 41, 66, 77, 78 SA/NSA/Sub6 - SM-G991B | ||
| Speed | HSPA 42.2/5.76 Mbps, LTE (7CA) Cat20 2000/200 Mbps, 5G (5+ Gbps DL) |
| Launch | Announced | 2021, January 14 |
|---|---|---|
| Status | Available. Released 2021, January 29 |
| Body | Dimensions | 151.7 x 71.2 x 7.9 mm (5.97 x 2.80 x 0.31 in) |
|---|---|---|
| Weight | 169 g (Sub6), 171 g (mmWave) (5.96 oz) | |
| Build | Glass front (Gorilla Glass Victus), plastic back, aluminum frame | |
| SIM | · Nano-SIM + eSIM · Nano-SIM + Nano-SIM + eSIM (max 2 at a time) | |
| IP68 dust tight and water resistant (immersible up to 1.5m for 30 min) |
| Display | Type | Dynamic AMOLED 2X, 120Hz, HDR10+, 1300 nits (peak) |
|---|---|---|
| Size | 6.2 inches, 94.1 cm2 (~87.2% screen-to-body ratio) | |
| Resolution | 1080 x 2400 pixels, 20:9 ratio (~421 ppi density) | |
| Protection | Corning Gorilla Glass Victus |
| Platform | OS | Android 11, up to 4 major Android upgrades, One UI 7 |
|---|---|---|
| Chipset | Exynos 2100 (5 nm) - International Qualcomm SM8350 Snapdragon 888 5G (5 nm) - USA/China | |
| CPU | Octa-core (1x2.9 GHz Cortex-X1 & 3x2.80 GHz Cortex-A78 & 4x2.2 GHz Cortex-A55) - International Octa-core (1x2.84 GHz Cortex-X1 & 3x2.42 GHz Cortex-A78 & 4x1.80 GHz Cortex-A55) - USA/China | |
| GPU | Mali-G78 MP14 - International Adreno 660 - USA/China |
| Memory | Card slot | No |
|---|---|---|
| Internal | 128GB 6GB RAM, 128GB 8GB RAM, 256GB 8GB RAM | |
| UFS 3.1 |
| Main Camera | Triple | 12 MP, f/1.8, 26mm (wide), 1/1.76", 1.8µm, dual pixel PDAF, OIS 64 MP, f/2.0, 29mm (telephoto), 1/1.72", 0.8µm, PDAF, OIS, 1.1x optical zoom, 3x hybrid zoom 12 MP, f/2.2, 13mm, 120˚ (ultrawide), 1/2.55" 1.4µm, Super Steady video |
|---|---|---|
| Features | LED flash, auto-HDR, panorama | |
| Video | 8K@24fps, 4K@30/60fps, 1080p@30/60/120/240fps, HDR10+, stereo sound rec., gyro-EIS |
| Selfie camera | Single | 10 MP, f/2.2, 26mm (wide), 1/3.24", 1.22µm, dual pixel PDAF |
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| Features | HDR | |
| Video | 4K@30/60fps, 1080p@30fps |
| Sound | Loudspeaker | Yes, with stereo speakers |
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| 3.5mm jack | No | |
| High-bitrate audio support |
| Comms | WLAN | Wi-Fi 802.11 a/b/g/n/ac/6, dual-band, Wi-Fi Direct |
|---|---|---|
| Bluetooth | 5.0, A2DP, LE | |
| Positioning | GPS, GLONASS, BDS, GALILEO | |
| NFC | Yes | |
| Radio | FM radio (Snapdragon model only; market/operator dependent) | |
| USB | USB Type-C 3.2, OTG |
| Features | Sensors | Fingerprint (under display, ultrasonic), accelerometer, gyro, proximity, compass, barometer |
|---|---|---|
| Samsung DeX, Samsung Wireless DeX (desktop experience support) |
| Battery | Type | Li-Ion 4000 mAh |
|---|---|---|
| Charging | 25W wired, PD3.0 15W wireless (Qi) 4.5W reverse wireless |
| Misc | Colors | Phantom Gray, Phantom White, Phantom Violet, Phantom Pink |
|---|---|---|
| Models | SM-G991B, SM-G991B/DS, SM-G991U, SM-G991U1, SM-G991W, SM-G991N, SM-G9910, SM-G991Q, SCG09 | |
| SAR | 0.74 W/kg (head) 1.08 W/kg (body) | |
| SAR EU | 0.46 W/kg (head) 1.51 W/kg (body) | |
| Price | $ 164.44 / € 156.88 / £ 130.00 |
| Our Tests | Performance | AnTuTu: 584055 (v8) GeekBench: 3238 (v5.1) GFXBench: 60fps (ES 3.1 onscreen) |
|---|---|---|
| Display | 856 nits max brightness (measured) | |
| Camera | Photo / Video | |
| Loudspeaker | -26.4 LUFS (Good) | |
| Battery (old) | Endurance rating 93h | |
A: Yes — official firmware from the manufacturer is generally safe when you match your device's exact model number and region. Flashing the wrong region or modified firmware can cause issues.
A: Samsung Galaxy S21 (Korea) firmware is flashed using Odin. See the step-by-step guide above for the full procedure.
A: Some devices allow downgrading, others have anti-rollback protection that blocks it. Check the version-specific notes on each ROM page, or your model's community forum, before attempting a downgrade.
A: First, verify the firmware matches your exact model code (e.g. SM-S938B for Samsung, or the CPH-number for OPPO). Reinstall the manufacturer's USB drivers, use a rear USB 2.0 port directly on your PC, and retry. The troubleshooting box above the FAQ covers the most common failure modes.
