Which has the bigger battery, the Nothing Phone (3) or the Nothing Phone (3a)?

The Nothing Phone (3) has the bigger battery: 5,150 mAh against 5,000 mAh. Real battery life also depends on the chip and screen.

Nothing Phone (3) vs Nothing Phone (3a)

The Nothing Phone (3) is 2.9 mm shorter, 1.9 mm narrower, 0.6 mm thicker and 17 g heavier than the Nothing Phone (3a). Its screen is 0.1" smaller.

Performance and software	Nothing Phone (3)	Nothing Phone (3a)
Chipset	Qualcomm SM8735 Snapdragon 8s Gen 4	Qualcomm SM7635 Snapdragon 7s Gen 3
CPU	Octa-core (1x3.21 GHz Cortex-X4 & 3x3.0 GHz Cortex-A720 & 2x2.8 GHz Cortex-A720 & 2x2.0 GHz Cortex-A720)1	Octa-core (1x2.5 GHz Cortex-A720 & 3x2.4 GHz Cortex-A720 & 4x1.8 GHz Cortex-A520)
Process	—	4 nm
Ships with	Android 15 with Nothing OS 3.5	Android 16 with Nothing OS 4.0
OS updates	—	3 years (to Mar 2028)
Security updates	—	6 years (to Mar 2031)

Cameras	Nothing Phone (3)	Nothing Phone (3a)
Rear	50 MP Main, OIS 50 MP Periscope telephoto (3× optical), OIS 50 MP Ultrawide	50 MP Main, OIS 50 MP Telephoto (2× optical) 8 MP Ultrawide
Main camera	50 MP	50 MP
Optical zoom	3× (better)	2×
Front	50 MP	32 MP
Video	4K at 60 fps1	4k @30 fps

Features	Nothing Phone (3)	Nothing Phone (3a)
Fingerprint	Under-display optical	On-screen optical1
Stereo speakers	Yes	Yes

Highlighted: the better value where one is clearly better. Sources for each phone are listed on the Nothing Phone (3) and Nothing Phone (3a) pages.

Is the Nothing Phone (3) bigger than the Nothing Phone (3a)?: The Nothing Phone (3) is 2.9 mm shorter, 1.9 mm narrower, 0.6 mm thicker and 17 g heavier than the Nothing Phone (3a). Its screen is 0.1" smaller.
Which has the bigger battery, the Nothing Phone (3) or the Nothing Phone (3a)?: The Nothing Phone (3) has the bigger battery: 5,150 mAh against 5,000 mAh. Real battery life also depends on the chip and screen.