Vortex5 · text · mixture of experts

Chimera-X-26B-A4B

Vortex5/Chimera-X-26B-A4B

Chimera-X-26B-A4B at Q4_K_M is exactly 17,211,252,736 bytes (16.03 GiB / 17.21 GB) — an effective 5.187 bits per weight, not the nominal 4. Its KV cache at 32K is 1.54 GiB, not the 7.50 GiB a flat formula predicts.

From the file· summed from 1 file(s)From the file· KV per layer
Parameters
26.5B
total, not active
Architecture
gemma4
30 layers
Context
262,144
native (config.json)
License
apache-2.0

Shipped quantizations

exact bytes, summed from published files
QuantSizeExact bytesEffective bpwTensorsPublisher
I1-IQ1_S7.95 GiB8,532,493,0562.572mradermacher
I1-IQ1_M8.30 GiB8,910,878,9762.686mradermacher
I1-IQ2_XXS8.89 GiB9,541,522,1762.876mradermacher
I1-IQ2_XS9.37 GiB10,058,652,4163.031mradermacher
I1-IQ2_S9.49 GiB10,190,396,1603.071mradermacher
I1-IQ2_M9.96 GiB10,694,910,7203.223mradermacher
Q2_K10.08 GiB10,824,958,9763.263mradermacher
I1-Q2_K10.08 GiB10,824,959,2323.263mradermacher
I1-Q2_K_S10.12 GiB10,866,703,6163.275mradermacher
I1-IQ3_XXS10.84 GiB11,642,888,9603.509mradermacher
I1-IQ3_XS11.13 GiB11,953,262,8483.603mradermacher
Q3_K_S11.68 GiB12,539,604,4803.779mradermacher
I1-IQ3_S11.68 GiB12,539,604,7363.779mradermacher
I1-Q3_K_S11.68 GiB12,539,604,7363.779mradermacher
I1-IQ3_M11.84 GiB12,709,758,7203.830mradermacher
Q3_K_M12.67 GiB13,603,928,5764.100mradermacher
I1-Q3_K_M12.67 GiB13,603,928,8324.100mradermacher
Q3_K_L13.17 GiB14,141,683,2004.262mradermacher
I1-Q3_K_L13.17 GiB14,141,683,4564.262mradermacher
I1-IQ4_XS13.33 GiB14,309,894,4004.313mradermacher
IQ4_XS13.46 GiB14,455,976,9604.357mradermacher
I1-Q4_013.88 GiB14,903,293,1844.492mradermacher
Q4_K_S14.79 GiB15,880,061,9524.786mradermacher
I1-Q4_K_S14.79 GiB15,880,062,2084.786mradermacher
I1-Q4_115.30 GiB16,430,950,6564.952mradermacher
Q4_K_M16.03 GiB17,211,252,7365.187mradermacher
I1-Q4_K_M16.03 GiB17,211,252,9925.187mradermacher
Q5_K_S17.22 GiB18,494,244,8645.574mradermacher
I1-Q5_K_S17.22 GiB18,494,245,1205.574mradermacher
Q5_K_M18.29 GiB19,640,401,9205.919mradermacher
I1-Q5_K_M18.29 GiB19,640,402,1765.919mradermacher
Q6_K21.65 GiB23,243,952,6407.005mradermacher
I1-Q6_K21.65 GiB23,243,952,8967.005mradermacher
Q8_025.75 GiB27,644,194,8168.332mradermacher

KV cache by context

computed per layer — this model uses sliding-window attention
ContextKV cache (f16)Flat formulaOverstated byFull / windowed / recurrent
4,0960.45 GiB0.94 GiB2.09×5 / 25 / 0
8,1920.61 GiB1.88 GiB3.10×5 / 25 / 0
16,3840.92 GiB3.75 GiB4.09×5 / 25 / 0
32,7681.54 GiB7.50 GiB4.86×5 / 25 / 0
65,5362.79 GiB15.00 GiB5.37×5 / 25 / 0
131,0725.29 GiB30.00 GiB5.67×5 / 25 / 0

25 of 30 layers cache only a 1,024-token window rather than the full context, on a period of . Figures assume the default configuration; --swa-full disables the saving entirely.

Compare with

same modality, comparable size

Will it run on your card?

full quant x context sweep

Why other calculators give a different number

A parameters × bits ÷ 8 estimate puts Q4_K_M at roughly 13.91 GiB. The real file is 16.03 GiB, because a quantization is a mixture and some tensors are always kept at higher precision. The larger discrepancy is the cache: a flat formula gives 7.50 GiB at 32K context where the real figure is 1.54 GiB, because most of this model's layers cache a fixed window rather than the whole context.

Architecture

from config.json
Layers
30
Attention heads
16
KV heads
8
Head dim
256
Hidden size
2816
Vocab
262,144
Sliding window
1024
SWA period
MLA
no
Experts
128
Experts per token
use_sliding_window

Questions people ask

How much VRAM does Chimera-X-26B-A4B need?
Q4_K_M is exactly 17,211,252,736 bytes (16.03 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
How large is Chimera-X-26B-A4B's KV cache?
1.54 GiB at 32K context with an f16 cache, computed per layer. Quantizing the cache to q8_0 roughly halves it, which is often the difference between a context length fitting and not.
Is Chimera-X-26B-A4B a mixture-of-experts model?
Yes — 128 experts, null routed per token. Every expert must be resident, but only the routed ones are read per token, which is why its memory requirement and its speed behave very differently.
Which quantization of Chimera-X-26B-A4B should I use?
Q4_K_M is the usual default. Pick the largest quantization that fits your card at the context you actually need — the table above gives exact sizes for every one published.