| Hardware and OS | Karbonn A21 | |
| Operating system | Android 4.0 (Ice Cream Sandwich) | |
| Processor | Dual-core 1.2 GHz | |
| Internal memory | 4 GB, 512 MB RAM | |
| External memory | microSD, up to 32 GB (dedicated slot) | |
| Display | Karbonn A21 | other phones |
| Type | TFT | |
| Size | 4.5" inc | |
| Resolution | 480 x 800 px | |
| Touchscreen | capacitive touchscreen | |
| Display area | 57.6 cm2 | |
| Display aspect ratio | 5:3 (height:width) | |
| Pixel Density | 207 PPI | |
| Colors | 256K | |
| Connectivity | Karbonn A21 | other phones |
| 2G Network | GSM 900 / 1800 / 1900 - SIM 1 & SIM 2 | |
| Wi-Fi | Wi-Fi 802.11 b/g/n | |
| Network | GSM / HSPA | |
| SIM card | Dual SIM (Mini-SIM) | |
| Bluetooth | 2.1, A2DP | |
| Edge | Yes | |
| GPRS | Yes | |
| GPS | Yes, with A-GPS | |
| Speed | HSPA 7.2/0.384 Mbps | |
| USB | microUSB 2.0 | |
| Camera | Karbonn A21 | other phones |
| Main camera | 5 MP, Single | |
| Specs | 5 MP, AF | |
| Features | LED flash | |
| Video | Yes | |
| Selfie camera | 1.3 MP, Single | |
| Multimedia | Karbonn A21 | other phones |
| 3.5 mm Jack | Yes | |
| Radio | No | |
| Design | Karbonn A21 | other phones |
| Colors | Pearl White | |
| Battery | Karbonn A21 | other phones |
| Battery capacity | 1800 mAh, Removable Li-Ion | |
| Battery life | Stand by time- Up to 200 h
Talking time- Up to 5 h
| |
| Other | Karbonn A21 | other phones |
| SAR | SAR EU - 0.44 W/kg (head) | |
| Release date | 2012 | |
| Sensors | Accelerometer, proximity | |
