Xiaomi 15 Ultra vs Pixel 9a: Is the Xiaomi 15 Ultra Worth £800 More?
Xiaomi 15 Ultra or Pixel 9a? We compare price, measured performance and real-world trade-offs to work out which is the better buy.
Priya Raghunathan
The short answer
Xiaomi 15 Ultra 7h 05m, Pixel 9a 7h 05m — the same test, run the same way. Where they part company is who they suit: the Xiaomi 15 Ultra is the one to get if you are photographers who want the closest thing to a compact camera in a phone, the Pixel 9a if you are almost everyone — the sensible default recommendation.
Price difference: The Pixel 9a undercuts the Xiaomi 15 Ultra by £800. That gap only matters if the extras below are ones you will actually use.
Specifications side by side
| Specification | Xiaomi 15 Ultra | Pixel 9a |
|---|---|---|
| Price | £1299 | £499 |
| Our score | 4 / 5 | 5 / 5 |
| Display | 6.73in LTPO AMOLED, 120Hz | 6.3in OLED, 120Hz |
| Chip | Snapdragon 8 Elite | Tensor G4 |
| RAM | 16GB | 8GB |
| Battery | 5410mAh | 5100mAh |
| Charging | 90W wired | 23W wired |
| Weight | 226g | 186g |
| Screen-on time | 7h 05m | 7h 05m |
How we tested
Every figure quoted above comes from the same protocol, run on every unit in this category. This one spent fourteen days as the reviewer’s only phone, SIM included. Screen at a metered 200 nits, adaptive refresh left on, the same twelve apps installed on every handset, and a fixed 5G network in the same building.
| What we measure | How |
|---|---|
| Screen-on time | A scripted day — four hours of mixed browsing, an hour of video, thirty minutes of camera, the rest idle — repeated three times and averaged. |
| Sustained performance | Twenty minutes of continuous load, reporting the figure at the end rather than the peak in the first ninety seconds. |
| Charging | From 2% to 100% with the fastest charger the manufacturer sells, at 22°C ambient, timed to the minute. |
| Camera | The same eighteen scenes on every phone — backlit portrait, indoor low light, moving subject — shot in the default mode with no editing. |
| Thermals | Surface temperature at the hottest point after the sustained run, measured with a contact probe. |
We deliberately do not report synthetic benchmark totals quoted in isolation, and any figure supplied by the manufacturer.
The honest caveat: Battery results are specific to our routine. A heavy camera user will see materially less screen-on time than these numbers suggest.
Where the Xiaomi 15 Ultra wins
- A one-inch main sensor with genuinely optical depth falloff
- An optional grip with a physical shutter
- Very fast charging
It also has the edge on the intangibles: night mode is rarely needed at all thanks to the sensor size.
Where the Pixel 9a wins
- Flagship camera processing at mid-range money
- Seven years of updates
- Better battery life than the Pro
And in day-to-day use, in daylight we struggled to tell its photographs from the 9 Pro.
The trade-offs
Neither is flawless. The Xiaomi 15 Ultra has one clear weak point — heavy — and the Pixel 9a has its own: no telephoto. Weigh those against how you actually work rather than against the spec sheet.
The value case
The Xiaomi 15 Ultra costs £800 more and scores 1 point higher — roughly £800 per point of difference. Whether that is good value depends on whether the extra buys you a one-inch main sensor with genuinely optical depth falloff, or only a number. In our testing it is the former, but only just.
If neither quite fits
Look at the Pixel 9 Pro at £999 — it scored 4 out of 5 and suits photographers who want the best point-and-shoot results with no editing. If the budget will not stretch, the Galaxy A56 at £399 is the cheapest option in this category we would still put our name to.
Living with each of them
On paper the gap looks like a specification difference; in use it is a habits difference. With the Xiaomi 15 Ultra the thing you adjust to is heavy, and you do adjust — within a week it stops registering. Its display (6.73in LTPO AMOLED, 120Hz) is the part you stop thinking about. The Pixel 9a asks for a different accommodation: no telephoto, against a display of 6.3in OLED, 120Hz that holds up better than the number suggests. Neither compromise is severe. They are simply different, and which one you would rather not think about is a more useful question than which is objectively smaller.
Which one ages better
Both launched in 2025, so neither starts with a support-window advantage. The other half of ageing is the weak point you already know about: heavy on one side, no telephoto on the other. Weaknesses of that kind do not improve with firmware, so assume you are buying them for the life of the device and price the decision accordingly.
Our recommendation
For most people we would take the Pixel 9a, which scored 5 out of 5 in our testing against 4 for the other. That said, a score is a summary, not a substitute for knowing what you need.
Buy the Xiaomi 15 Ultra for a one-inch main sensor with genuinely optical depth falloff. Buy the Pixel 9a for flagship camera processing at mid-range money.
Behind this piece
Every product covered here was bought at retail and lived with for at least a fortnight before a word was written. Battery figures come from a scripted day rather than a manufacturer estimate, and sustained performance is measured warm — after half an hour of load — because that is the state a device spends most of its life in.
Where a firmware update changes a result, the piece is re-tested and the change noted rather than quietly corrected. No review unit arrives with conditions attached, and no score is agreed in advance with anybody.
Where to go next
If you are weighing this against the rest of the smartphones we have covered, the category archive lists every review in date order. The closest comparisons we have published are Xiaomi 15 Ultra: Battery Draining Faster Than It Should and Xiaomi 15 Ultra: Bluetooth Keeps Disconnecting.
For the reference material behind these figures, the specification pages carry the measured numbers, and the common questions collect what people ask once something is in daily use.
