S5-nano#
This repository contains the BF16 version of S5-nano (9.3 GB), with the original, unquantized weights for vLLM and SGLang. The FP8 version reduces the weight size to 5.8 GB and is recommended for GPUs with native FP8 support. The GGUF versions are for llama.cpp and compatible applications, with BF16 (8.7 GB), Q8_0 (4.6 GB), and Q4_K_M (2.8 GB) options.
S5-nano is a 4B-parameter model built by Maritaca AI on Qwen3.5-4B through continued pretraining followed by post-training. It delivers substantial improvements on Brazilian benchmarks while maintaining strong performance in function calling, tool use, and structured outputs.
It has two modes:
- Think: reasons before answering (the default mode).
- Instruct: answers directly, without a reasoning step.
The context window supports up to 262,144 tokens, and the weights include an MTP (multi-token prediction) layer for speculative decoding.
Versions#
FP8 is recommended for GPUs with native FP8 support (Ada, Hopper, and Blackwell). The GGUF repository provides BF16, Q8_0, and Q4_K_M variants.
The FP8 version uses E4M3 weights for linear layers, with one scale per output channel, and dynamically quantizes activations per token during inference. Embeddings, the vision encoder, the MTP layer, and some small projections remain in BF16.
Evaluation results#
Explore the results in Observatório Maritaca
Results for the original S5-nano checkpoint, evaluated in BF16 on text tasks.
Averages#
Each primary metric is weighted equally.
Image: Overall averages in Think mode, with benchmark coverage
Image: Overall averages in Instruct mode, with benchmark coverage
| Model | Mode | Native BR | Translated PT | Non-native | Total | Coverage
| Think
| S5-nano 🇧🇷 | Think | 83.74 | 86.94 | 54.11 | 75.25 | 23/23
| Qwen3.5-4B | Think | 72.49 | 87.61 | 54.82 | 68.68 | 23/23
| LFM2.5-24B-A2B | Think | 69.68 | 87.30 | 56.45 | 67.06 | 23/23
| Nemotron 3.5 Bolt E4B | Think | 71.42 | 84.92 | 50.78 | 64.95 | 23/23
| Gemma 4 E4B | Think | 71.64 | 83.82 | 47.22 | 63.68 | 23/23
| LFM3-1.7B | Think | 57.60 | 74.76 | 50.71 | 57.94 | 23/23
| Lumi 4B 🇧🇷 | Think | 52.68 | 52.50 | 33.97 | 44.77 | 23/23
| Tucano2-qwen-3.7B 🇧🇷 | Think | 34.83 | 46.12 | 30.45 | 33.13 | 22/23
| Instruct
| S5-nano 🇧🇷 | Instruct | 74.65 | 83.48 | 44.06 | 66.51 | 23/23
| Qwen3.5-4B | Instruct | 66.22 | 84.94 | 47.20 | 61.84 | 23/23
| Nemotron 3.5 Bolt E4B | Instruct | 67.58 | 81.16 | 46.57 | 60.47 | 23/23
| Gemma 4 E4B | Instruct | 68.10 | 77.91 | 44.61 | 59.93 | 23/23
| LatamGPT 70B | Instruct | 47.66 | 66.97 | 42.99 | 48.19 | 20/23
| Gaia 4B 🇧🇷 | Instruct | 46.25 | 66.90 | 34.95 | 43.26 | 23/23
| LFM3-1.7B | Instruct | 47.17 | 11.57 | 39.33 | 42.31 | 23/23
| Lumi 4B 🇧🇷 | Instruct | 43.40 | 59.48 | 35.16 | 40.55 | 23/23
| Tucano2-qwen-3.7B 🇧🇷 | Instruct | 31.87 | 40.97 | 25.30 | 29.75 | 23/23
| Manacá 🇧🇷 | Instruct | 7.01 | 27.76 | 19.56 | 12.85 | 20/23
Compared models and sizes
Total, active, and effective parameter counts measure different things. LatamGPT 70B is a larger reference model; LFM2.5 has approximately 24B total parameters and 2B active parameters.
| Model | Parameters
| S5-nano 🇧🇷 | ≈4.2B · text
| Qwen3.5-4B | 4.66B · ≈4.2B text
| Gemma 4 E4B | 8B total · 4B effective
| Nemotron 3.5 Bolt E4B | 8B total · 4B effective
| LFM3-1.7B | 1.73B total
| LFM2.5-24B-A2B | 23.97B total · ≈2B active
| Gaia 4B 🇧🇷 | 4.30B total
| Manacá 🇧🇷 | 1.72B total
| Tucano2-qwen-3.7B 🇧🇷 | 3.76B total
| Lumi 4B 🇧🇷 | 3.97B total
| LatamGPT 70B | 70.55B · larger reference model
Results by benchmark#
Bold indicates the best result within each group with a documented evaluation protocol, in the same mode. Different groups may produce more than one highlighted result in the same row. † indicates that the model produced reasoning in Instruct mode even though it was disabled in the request.
Think / Thinking#
| Evaluation / metric | S5-nano 🇧🇷 | Qwen3.5-4B | Gemma 4 E4B | Nemotron 3.5 Bolt E4B | LFM3-1.7B | LFM2.5-24B-A2B | Tucano2-qwen-3.7B 🇧🇷 | Lumi 4B 🇧🇷
| Arena-Hard v2 · Weighted preference | 19.12 | 11.67 | 20.06 | 25.82 | 11.18 | 21.65 | 0.35 | 3.62
| Prosa-PT · Rubrics passed | 75.07 | 56.89 | 60.14 | 59.87 | 51.24 | 54.41 | 25.94 | 30.90
| IFBench · Strict prompt-level | 42.67 | 49.67 | 37.33 | 59.67 | 68.67 | 71.67 | 12.33 | 23.67
| CAPITU · Strict single-turn | 95.50 | 90.00 | 85.00 | 89.00 | 96.00 | 98.00 | 50.00 | 65.00
| CAPITU · full conversations · Strict full-conversation | 97.00 | 92.00 | 74.00 | 81.00 | 94.00 | 95.00 | 33.00 | 37.00
| Lumen PT · Safety · normalized score | 98.92 | 94.75 | 99.23 | 99.92 | 77.62 | 91.51 | No demonstrated capability | 98.23
| HarmBench · Safety · normalized score | 91.25 | 96.56 | 83.12 | 91.56 | 84.69 | 89.06 | 90.62 | 94.69
| MMLU-PT · high school · Accuracy | 82.83 | 81.85 | 74.81 | 74.62 | 53.31 | 75.53 | 3.57 | 59.98
| MMLU-PT · undergraduate · Accuracy | 80.54 | 63.92 | 65.04 | 64.42 | 42.70 | 57.82 | 9.66 | 47.84
| Global-MMLU PT · Accuracy | 78.22 | 81.43 | 73.64 | 75.84 | 62.28 | 79.27 | 3.34 | 44.37
| ENADE-QA · Accuracy | 81.70 | 79.75 | 72.07 | 72.63 | 60.34 | 74.58 | 50.98 | 61.73
| ENEM-VL · text · Accuracy | 92.91 | 92.00 | 88.83 | 90.59 | 81.29 | 84.46 | 71.38 | 80.18
| BLUEX v2 · text · Rubric-based score | 87.89 | 84.46 | 82.89 | 80.03 | 81.50 | 82.60 | 62.71 | 65.16
| MATH-PT · PT-BR · Accuracy | 87.77 | 91.07 | 85.58 | 80.72 | 85.42 | 90.75 | 20.06 | 81.50
| MARCA public · Criteria met | 89.57 | 78.23 | 35.11 | 40.01 | 79.32 | 66.82 | 5.61 | 2.15
| BrowseComp-Plus · Accuracy / total | 37.00 | 27.00 | 8.00 | 7.00 | 29.00 | 28.00 | 0.00 | 4.00
| Structured Output Benchmark · Weighted JSON pass rate | 97.33 | 96.64 | 93.94 | 94.91 | 98.40 | 98.19 | 70.78 | 86.46
| BRoverbs · Mean accuracy | 92.83 | 79.97 | 82.73 | 87.13 | 40.76 | 68.91 | 69.43 | 31.35
| ASSIN 2 · RTE · Macro F1 | 95.67 | 93.80 | 94.00 | 94.00 | 87.24 | 95.33 | 88.89 | 60.62
| CulturalBench Hard · Fully correct groups | 41.73 | 48.08 | 44.34 | 41.32 | 29.01 | 47.60 | 29.10 | 16.22
| LongBench v2 · Accuracy | 49.70 | 54.08 | 43.74 | 35.19 | 34.00 | 38.97 | 9.94 | 9.15
| OAB-Bench · 210 · full · Mean score per exam × 10 | 82.00 | 45.88 | 53.19 | 50.43 | 27.93 | 40.83 | 25.39 | 31.18
| Magis-Bench · 74 · full · Mean score per section × 10 | 50.41 | 13.97 | 23.38 | 21.86 | 7.81 | 15.42 | 3.33 | 4.50
| CondutaBench · 140 · Native clinical score | 80.24 | 67.92 | 58.49 | 57.27 | 42.81 | 70.98 | 25.47 | 27.33
Instruct#
| Evaluation / metric | S5-nano 🇧🇷 | Qwen3.5-4B | Gemma 4 E4B | Nemotron 3.5 Bolt E4B | LFM3-1.7B | Gaia 4B 🇧🇷 | Manacá 🇧🇷 | Tucano2-qwen-3.7B 🇧🇷 | Lumi 4B 🇧🇷
The publisher's README is longer; it is cut here. Read the rest at the source.