| Hardware and OS | Realme Narzo 21 | |
| Operating system | Android v11 | |
| Processor | MediaTek Helio G85 (12nm) | |
| RAM | 4 GB | |
| Internal Storage | 64 GB | |
| Display | Realme Narzo 21 | other phones |
| Type | IPS LCD | |
| Size | 6.5 inches | |
| Resolution | 720 x 1600 Pixels | |
| Pixel Density | 270 ppi | |
| Touchscreen | Yes, Capacitive Touchscreen, Multi-touch | |
| Aspect ratio | 20:9 | |
| Connectivity | Realme Narzo 21 | other phones |
| Network support | 4G , 3G, 2G | |
| WI-FI | Yes, Wi-Fi 802.11, b/g/n | |
| Gps | Yes, with A-GPS, Glonass | |
| Bluetooth | Yes, v5.0 | |
| NFC | Yes | |
| Dual SIM | Dual SIM, GSM GSM | |
| SIM size | SIM1: Nano, SIM2: Nano | |
| USB connectivity | Mass storage device, USB charging | |
| Camera | Realme Narzo 21 | other phones |
| Front camera resolution | 8 MP Primary Camera | |
| Camera features | Digital Zoom, Auto Flash, Face detection, Touch to focus | |
| Flash | Yes, LED Flash | |
| Autofocus | Yes | |
| Video recording | Yes | |
| Multimedia | Realme Narzo 21 | other phones |
| Audio jack | 3.5 MM | |
| Loudspeaker | Yes | |
| Design | Realme Narzo 21 | other phones |
| Height | 164.5 mm | |
| Width | 75.9 mm | |
| Thickness | 9.8 mm | |
| Weight | 208 grams | |
| Colours | Glory Silver, Victory Blue | |
| Battery | Realme Narzo 21 | other phones |
| Capacity | 6000 mAh | |
| Type | Li-Polymer | |
| User replaceable | No | |
| Other | Realme Narzo 21 | other phones |
| Fingerprint sensor | Yes | |
| Fingerprint sensor position | Rear | |
| Other sensors | Accelerometer, Proximity, Compass | |
