Reasons to choose D3100
Released in 2010, D3100 has about 356 mm² of sensor area, 14.2 MP effective resolution, and a 505 g body. Use these values to narrow the field, not as an overall image-quality score.
Side-by-side comparison
Nikon D3100
vs Nikon D7100
VS
Sensor area
356 mm²
D3100367 mm²
D7100- Area ratio
- 1.03:1
- Absolute difference
- 11 mm²
- Relative difference
- 3.1%
The D7100 has the larger sensor area. More area usually means greater light-gathering potential, though real image quality still depends on sensor architecture and generation.
These cameras were released 3 years apart. Consider sensor generation when comparing pixel metrics.
Key specification differences
D3100MetricD7100
14.2 MPEffective pixels24.1 MP
23.1 × 15.4Sensor23.5 × 15.6
5.01 µmPixel pitch3.9 µm
25.05 µm²Pixel area15.21 µm²
3.99 MP/cm²Pixel density6.57 MP/cm²
1.56Crop factor1.53
1,920 × 1,080Maximum video1,920 × 1,080
505 gWeight675 g
SDHC, SDXC, Secure DigitalStorageSD/SDHC/SDXC x 2
Lithium-Ion EN-EL14 rechargeable battery Li-ion batteryBatteryLithium-Ion EN-EL15 rechargeable battery Li-ion battery
Amber marks the value that is generally preferable in this comparison context. It is not an overall camera score.
How to choose between these cameras
The D7100 has the larger sensor area. The D3100 has the lighter body. The D7100 has the higher effective resolution. The D7100 is the newer release. Also consider the lens system and subjects you shoot.
Reasons to choose D7100
Released in 2013, D7100 has about 367 mm² of sensor area, 24.1 MP effective resolution, and a 675 g body. Use these values to narrow the field, not as an overall image-quality score.