Qwen on NVIDIA Ada

Can I run Qwen3 4B on an RTX 4090?

Yes. Qwen3 4B at Q4_K_M uses 4.2 GB of the 21.8 GB available on a RTX 4090, and runs at about 202 tokens per second. You can push the context to 128K.

Runs comfortably

4.2 GB of 21.8 GB · 19%
022 GB
Weights 2.3 GB
KV cache 1.1 GB
Runtime overhead 0.8 GB

Qwen3 4B at Q4_K_M leaves 17.5 GB spare on a RTX 4090. There is room to raise the context length or move up a quantisation level.

Generation202tok/s
Prompt processing8619tok/s
Max context128Ktokens
KV per 1K tokens0GB

Every quantisation of Qwen3 4B on a RTX 4090

Highlighted row is the highest quality that still fits at 8K context.

QuantisationbpwWeights TotalVerdictMax ctxtok/s
FP16 / BF16 16.00 7.5 GB 9.4 GB Runs comfortably 96K 73.9
INT8 / W8A8 8.50 3.9 GB 5.8 GB Runs comfortably 121K 132
Q8_0 (GGUF) 8.50 3.9 GB 5.8 GB Runs comfortably 121K 132
FP8 (E4M3) 8.00 3.7 GB 5.7 GB Runs comfortably 122K 136
Q6_K 6.56 3.1 GB 5.0 GB Runs comfortably 127K 161
Q5_K_M 5.67 2.7 GB 4.6 GB Runs comfortably 128K 181
Q5_K_S 5.52 2.6 GB 4.5 GB Runs comfortably 128K 184
AWQ 4-bit 4.25 2.5 GB 4.4 GB Runs comfortably 128K 188
GPTQ 4-bit 4.25 2.5 GB 4.4 GB Runs comfortably 128K 188
MXFP4 4.25 2.5 GB 4.4 GB Runs comfortably 128K 188
Q4_K_M 4.85 2.3 GB 4.2 GB Runs comfortably 128K 202
Q4_K_S 4.58 2.2 GB 4.1 GB Runs comfortably 128K 210
Q4_0 4.55 2.2 GB 4.1 GB Runs comfortably 128K 211
IQ4_XS 4.25 2.0 GB 4.0 GB Runs comfortably 128K 221
Q3_K_M 3.91 1.9 GB 3.8 GB Runs comfortably 128K 233
IQ3_M 3.70 1.8 GB 3.7 GB Runs comfortably 128K 241
IQ3_XXS 3.06 1.5 GB 3.5 GB Runs comfortably 128K 270
Q2_K 2.63 1.4 GB 3.3 GB Runs comfortably 128K 294
IQ2_XXS 2.06 1.1 GB 3.0 GB Runs comfortably 128K 333
IQ1_M 1.75 1.0 GB 2.9 GB Runs comfortably 128K 359

Also worth checking

Qwen3 4B on every GPU
Full hardware tableEverything that runs on a RTX 4090
Full model tableWhy the KV cache is the part that bites
Guide