Can Gemma 3 12B run on RX 6900 XT 16GB?

YES — Tight Fit

A80Great

Estimated from fit model

Gemma 3 12B needs ~14.7 GB VRAM. RX 6900 XT 16GB has 16.0 GB. With Q4_K_M quantization, expect ~32 tok/s.

Runtime: llama.cppCapacity: TightBandwidth: MediumStack: StandardBottleneck: Balanced

Operating mode

Choose the run profile you care about

Interactive favors responsiveness, while light API and scale-out lean harder on serving readiness. The fit stays the same, but the recommendation lens changes.

Current mode

Balanced

Balanced for general local use. Keeps the ranking neutral across personal and serving workflows.

Capabilities:

Select quantization to explore

Q4_K_M (Medium quality) — 14.7 GB, 31.7 tok/s, Tight fit

14.7 GB required16.0 GB available

92% VRAM used

Fit status

Tight fit

Decode

31.7 tok/s

TTFT

6102 ms

Safe context

20K

Memory

14.7 GB / 16.0 GB

Memory breakdown

Weights7.3 GB

KV Cache4.9 GB

Runtime0.9 GB

Headroom1.6 GB

See how fast it feels

See how fast it feelsGemma 3 12B on RX 6900 XT 16GB
1st promptCold start — includes initialization
>Write a Python function to sort a list
Here's a Python function that sorts a list using quicksort:

def quicksort(arr):
    if len(arr) <= 1:
        return arr
    pivot = arr[len(arr) // 2]
    left   = [x for x in arr if x < pivot]
    middle = [x for x in arr if x == pivot]
    right  = [x for x in arr if x > pivot]
    return quicksort(left) + middle + quicksort(right)

# Example usage
numbers = [3, 6, 8, 10, 1, 2, 1]
print(quicksort(numbers))  # [1, 1, 2, 3, 6, 8, 10]

The algorithm picks a pivot, partitions the list into smaller, equal, and larger elements, then recursively sorts each partition and concatenates the results.
2nd promptWarm — model ready, no init overhead
>Now add type hints and a docstring
def quicksort(arr: list[int]) -> list[int]:
    """Sort a list using the quicksort algorithm.

    Args:
        arr: List of integers to sort.

    Returns:
        A new sorted list.
    """
    if len(arr) <= 1:
        return arr
    pivot = arr[len(arr) // 2]
    left   = [x for x in arr if x < pivot]
    middle = [x for x in arr if x == pivot]
    right  = [x for x in arr if x > pivot]
    return quicksort(left) + middle + quicksort(right)

Added type hints for the input and return type, plus a Google-style docstring.
Estimated: 31.7 tok/s decode · 6.1s TTFT (warm) · 79 tok/s prefill

What limits this setup

This setup is broadly balanced for this model.

No major red flags

This recommendation has enough memory headroom and acceptable estimated speed for the selected workload.

Best improvement path

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	A	Runs well	31.7 tok/s	3329 ms	20K
Coding	A	Tight fit	31.7 tok/s	6102 ms	20K
Agentic Coding	F	Too heavy	15.5 tok/s	18114 ms	20K
Reasoning	A	Tight fit	31.7 tok/s	7212 ms	20K
RAG	F	Too heavy	15.5 tok/s	22643 ms	20K

Quantization options

How Gemma 3 12B (12B params) fits at each quantization level on RX 6900 XT 16GB (16.0 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	4.7 GB	Low	A78
Q3_K_S	3	5.9 GB	Low	A79
NVFP4	4	6.7 GB	Medium	A80
Q4_K_M	4	7.3 GB	Medium	A81
Q5_K_M	5	8.6 GB	High	A81
Q6_KBest for your GPU	6	9.8 GB	High	A81
Q8_0	8	12.8 GB	Very High	F0
F16	16	24.6 GB	Maximum	F0

Get started

Copy-paste commands to run Gemma 3 12B on your machine.

Run

ollama run gemma3:12b

Your hardware

More models your RX 6900 XT 16GB can run

Model	Params	Grade	Decode
Qwen 3 14B	14B	S	36.9 tok/s
Phi-4-reasoning-plus 14B	14.7B	S	35 tok/s
GPT-OSS 20B	21B	A	33.8 tok/s
Ministral 3 14B	14B	S	36.7 tok/s
Codestral 2 25.08	22B	A	12.3 tok/s

Frequently asked questions

Can RX 6900 XT 16GB run Gemma 3 12B?

Yes, RX 6900 XT 16GB can run Gemma 3 12B with a A grade (Tight fit). Expected decode speed: 31.7 tok/s.

How much VRAM does Gemma 3 12B need?

Gemma 3 12B (12B parameters) requires approximately 14.7 GB of memory with Q4_K_M quantization.

What is the best quantization for Gemma 3 12B?

The recommended quantization for Gemma 3 12B is Q4_K_M, which balances quality and memory efficiency.

What speed will Gemma 3 12B run at on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Gemma 3 12B achieves approximately 31.7 tokens per second decode speed with a time-to-first-token of 6102ms using Q4_K_M quantization.

Can RX 6900 XT 16GB run Gemma 3 12B for coding?

For coding workloads, Gemma 3 12B on RX 6900 XT 16GB receives a A grade with 31.7 tok/s and 20K context.

What context window can Gemma 3 12B use on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Gemma 3 12B can safely use up to 20K tokens of context. The model's official context limit is 131K, but available memory constrains the safe maximum.

See all results for RX 6900 XT 16GB See all hardware for Gemma 3 12B

Embed this result▼

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<iframe src="https://willitrunai.com/embed/gemma-3-12b-on-rx-6900-xt-16gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>

Preview:

Workload

Grade

Fit

Decode

TTFT

Context

Chat

Runs well

31.7 tok/s

3329 ms

20K

Coding

Tight fit

31.7 tok/s

6102 ms

20K

Agentic Coding

Too heavy

15.5 tok/s

18114 ms

20K

Reasoning

Tight fit

31.7 tok/s

7212 ms

20K

RAG

Too heavy

15.5 tok/s

22643 ms

20K

Quant

Bits

VRAM

Quality

Fit

Q2_K

4.7 GB

Low

A78

Q3_K_S

5.9 GB

Low

A79

NVFP4

6.7 GB

Medium

A80

Q4_K_M

7.3 GB

Medium

A81

Q5_K_M

8.6 GB

High

A81

Q6_KBest for your GPU

9.8 GB

High

A81

Q8_0

12.8 GB

Very High

F16

24.6 GB

Maximum

Model

Params

Grade

Decode

Capabilities

Qwen 3 14B

14B

36.9 tok/s

Phi-4-reasoning-plus 14B

14.7B

35 tok/s

GPT-OSS 20B

21B

33.8 tok/s

Ministral 3 14B

14B

36.7 tok/s

Codestral 2 25.08

22B

12.3 tok/s

Frequently asked questions

Can RX 6900 XT 16GB run Gemma 3 12B?

Yes, RX 6900 XT 16GB can run Gemma 3 12B with a A grade (Tight fit). Expected decode speed: 31.7 tok/s.

How much VRAM does Gemma 3 12B need?

Gemma 3 12B (12B parameters) requires approximately 14.7 GB of memory with Q4_K_M quantization.

What is the best quantization for Gemma 3 12B?

The recommended quantization for Gemma 3 12B is Q4_K_M, which balances quality and memory efficiency.

What speed will Gemma 3 12B run at on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Gemma 3 12B achieves approximately 31.7 tokens per second decode speed with a time-to-first-token of 6102ms using Q4_K_M quantization.

Can RX 6900 XT 16GB run Gemma 3 12B for coding?

For coding workloads, Gemma 3 12B on RX 6900 XT 16GB receives a A grade with 31.7 tok/s and 20K context.

What context window can Gemma 3 12B use on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Gemma 3 12B can safely use up to 20K tokens of context. The model's official context limit is 131K, but available memory constrains the safe maximum.