Which has the bigger battery, the Google Pixel 9a or the Xiaomi 15?

The Xiaomi 15 has the bigger battery: 5,240 mAh against 5,100 mAh. Real battery life also depends on the chip and screen.

Google Pixel 9a vs Xiaomi 15

The Google Pixel 9a is 2.6 mm taller, 2.5 mm wider, 0.8 mm thicker and 3.9 g lighter than the Xiaomi 15. Its screen is 0.06" smaller.

Body	Google Pixel 9a	Xiaomi 15
Size	154.9 × 73.7 × 8.9 mm	152.3 × 71.2 × 8.1 mm
Thickness	8.9 mm?	8.1 mm (better)
Weight	187.1 g (better)	191 g?
Frame	Satin metal	aviation-grade aluminum1
Back	Composite matte	—
Water resistance	IP68	IP68
Colours	Obsidian, Porcelain, Iris, Peony	Liquid Silver, White, Black, Green

Performance and software	Google Pixel 9a	Xiaomi 15
Chipset	Google Tensor G4	Snapdragon 8 Elite Mobile Platform
CPU	—	2 x Prime Core up to 4.32GHz, 6 x Performance Core up to 3.53GHz
Process	—	3 nm
Ships with	Android 15	Xiaomi HyperOS 2
OS updates	7 years (to Apr 2032)	—
Security updates	7 years (to Apr 2032)	—

Cameras	Google Pixel 9a	Xiaomi 15
Rear	48 MP Main, OIS 13 MP Ultrawide	50 MP Main 50 MP Telephoto 50 MP Ultrawide
Main camera	48 MP	50 MP
Optical zoom	None	None
Front	13 MP	32 MP
Video	4K at 60 FPS	8K (7680x4320) at 24/30fps

Features	Google Pixel 9a	Xiaomi 15
Fingerprint	Under display	Ultrasonic in-screen
Stereo speakers	Yes	Yes

Highlighted: the better value where one is clearly better. Sources for each phone are listed on the Google Pixel 9a and Xiaomi 15 pages.

Is the Google Pixel 9a bigger than the Xiaomi 15?: The Google Pixel 9a is 2.6 mm taller, 2.5 mm wider, 0.8 mm thicker and 3.9 g lighter than the Xiaomi 15. Its screen is 0.06" smaller.
Which has the bigger battery, the Google Pixel 9a or the Xiaomi 15?: The Xiaomi 15 has the bigger battery: 5,240 mAh against 5,100 mAh. Real battery life also depends on the chip and screen.