Can Qwen3 4B run on iPhone 15?
YES — Runs, barely
Grade B · 68/100 · formula estimate
What this means
Our estimate says Qwen3 4B should fit, but there is very little memory left for the operating system and other apps.
Download the Q4_K_M version, which is about 2.5 GB. We expect it to use about 3.5 GB of the roughly 3.9 GB available to a model on this phone.
At the estimated speed, a roughly 300-word answer may take about 43 seconds to finish.
This result is calculated from the phone and model specifications. It has not been measured on this exact phone and setup.
9.2tokens/s
estimated · faster than you read
3.5GB
needed at Q4_K_M
Q4_K_M
quant checked
B
grade · 68/100
needs 3.5 GBusable 3.9 GB
Apple A16 Bionic6 GB RAMMetal
Make it bearable
1
Drop context to 2K — saves ~0.2 GB of KV cache and a little speed.
2
Close every other app before loading — the 0.4 GB headroom is real; iOS may evict the model otherwise.
3
Expect throttling after ~10 min of sustained generation on a phone chassis.
See how fast it feels
Estimated at 9.2 tokens/s — faster than you read. A ~300-word reply takes about 43 seconds on this phone.
Where the memory goes
| Component | Detail | GB |
|---|---|---|
| Model weights | Q4_K_M GGUF (2.5 GB) + mmap overhead | 2.6 |
| KV cache | 4K context window | 0.3 |
| Runtime | llama.cpp + app overhead | 0.6 |
| Total needed | at Q4_K_M, 4K context | 3.5 |
| Usable on iPhone 15 | 6 GB RAM − iOS reserve (jetsam limit) | 3.9 |
| Headroom | left for the OS and your other apps | 0.4 |
Pick your quant
| Quant | Download | Verdict | Speed |
|---|---|---|---|
| Q4_K_M BEST HERE | 2.5 GB | ! Runs, barely | ~9.2 tokens/s |
| Q5_K_M | 2.9 GB | ✕ Won't fit | won't fit |
| Q6_K | 3.3 GB | ✕ Won't fit | won't fit |
| Q8_0 | 4.3 GB | ✕ Won't fit | won't fit |
Get it running in 3 steps
1
Install PocketPal from the App Store — free, no account needed.
2
Download "Qwen3 4B Q4_K_M" in the in-app model hub — 2.5 GB, use Wi-Fi. Search Hugging Face for
Qwen/Qwen3-4B-GGUF and pick the Q4_K_M file.3
Set context to 4K and enable Metal — expect ~9.2 tokens/s on this phone.
Related checks
MORE ON IPHONE 15
QWEN3 4B ON OTHER PHONES