| Hardware and OS | Karbonn X21 | |
| Operating System | Android v10 | |
| Processor | 1.6 GHz, Octa Core Processor | |
| Chipset | Unisoc SC9863 | |
| RAM | 2 GB | |
| Internal Memory | 32 GB | |
| Memory Card Slot | Yes, upto 256 GB | |
| Dual Sim | Yes | |
| Sim Size | Nano Nano SIM | |
| Sim Type | Dual Sim, GSM GSM | |
| Display | Karbonn X21 | other phones |
| Screen Size | 5.45 inches, 1440 x 720 pixels | |
| Display Type | Color HD FullView Display | |
| Pixel Density | ~295 PPI | |
| Touch Screen | Yes, with Multitouch | |
| Display aspect ratio | 18:9 | |
| Connectivity | Karbonn X21 | other phones |
| 3G Network | Yes | |
| 4G Network | Yes | |
| Bluetooth | Yes, v4.2 | |
| EDGE | Yes | |
| GPRS | Yes | |
| GPS | Yes | |
| USB | Yes, microUSB | |
| USB Features | USB on-the-go, USB Charging | |
| VoLTE | Yes | |
| Wifi | Yes, with wifi-hotspot | |
| Camera | Karbonn X21 | other phones |
| Main camera | 8 MP with autofocus | |
| Video Recording | 1080p | |
| Flash | Yes, LED | |
| Selfie camera | 5 MP with LED Flash | |
| Features | Panorama, Burst Mode, Time Lapse, Face Beauty, Night Mode | |
| Multimedia | Karbonn X21 | other phones |
| Headphone jack | Yes | |
| Email | Yes | |
| FM Radio | Yes | |
| Music | Yes | |
| Video | Yes | |
| Browser | Yes | |
| Java | No | |
| Design | Karbonn X21 | other phones |
| Dimensions | 147.5 x 71.8 x 9.35 mm | |
| Weight | 160 g | |
| Battery | Karbonn X21 | other phones |
| Battery capacity | 3000 mAh | |
| Type | Removable Battery | |
| Reverse Charging | Yes | |
