# Best LLM for Math & Reasoning

> Updated Oct 20, 2026 · evidence through Oct 20, 2026. Synthesized from cited community evidence and open benchmarks, not vendor marketing. Canonical page: https://modelmatchbook.com/best/math-reasoning

Claude Fable 5.1 ranks first for Math & Reasoning as of October 20, 2026. It scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics. Claude Opus 5.5 scores within two points, so read the top two as close rather than as a measured gap. Claude Opus 5.5 is the next-ranked alternative. It leads LiveBench Mathematics at 97.08% (#1 of 59), ranks #1 on LMArena instruction-following (Elo 1536), and solves 91.2% of FrontierMath tiers 1 to 3 for research-level mathematics. [1,2,3,4]

## 1. Claude Fable 5.1
https://modelmatchbook.com/models/anthropic/claude-fable-5.1-20260831

Claude Fable 5.1 scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics.

**Best when:** Its strongest result for this task is on OTIS Mock AIME, which measures competition mathematics. [1]

## 2. Claude Opus 5.5
https://modelmatchbook.com/models/anthropic/claude-opus-5.5-20260921

Claude Opus 5.5 leads LiveBench Mathematics at 97.08% (#1 of 59), ranks #1 on LMArena instruction-following (Elo 1536), and solves 91.2% of FrontierMath tiers 1 to 3 for research-level mathematics.

**Best when:** Choose for the highest LiveBench Mathematics performance at 97.08% (#1 of 59) alongside perfect 100% on OTIS Mock AIME 2024-2025. [2,5]

**More tips:**
- Use when instruction-following matters: it ranks #1 of 152 on LMArena's instruction-following category with Elo 1536. [3]
- Deploy for graduate-level science questions where it scores 90.6% on GPQA Diamond. [6]

## 3. Gemini 4 Argon
https://modelmatchbook.com/models/google/gemini-4-argon-20261013

Gemini 4 Argon dominates LMArena rankings with #1 overall text arena (Elo 1524), #1 maths category (Elo 1536), and #1 instruction-following (Elo 1536).

**Best when:** Select for human preference on math prompts where it ranks #1 of 148 on LMArena's maths category with Elo 1536. [7]

**More tips:**
- Use for graduate-level science questions where it leads GPQA Diamond at 96.4% (#1 of 113). [8]
- Deploy for competition mathematics with perfect 100% on OTIS Mock AIME 2024-2025. [9]

**Watch out for:**
- Note lower research-level mathematics coverage: it solves 86% of FrontierMath tiers 1 to 3 (#10 of 73), trailing top performers in this specific benchmark. [10]

## 4. GPT-6.1 Sol
https://modelmatchbook.com/models/openai/gpt-6.1-sol-20260929

GPT-6.1 Sol leads FrontierMath research-level mathematics at 93.7% (#1 of 73), scores 96.83% on LiveBench Mathematics (#3 of 59), and achieves 100% on OTIS Mock AIME 2024-2025.

**Best when:** Prioritize for research-level mathematics where it solves 93.7% of FrontierMath tiers 1 to 3, ranking #1 of 73. [11]

**More tips:**
- Use for graduate-level science questions with 95.4% on GPQA Diamond (#4 of 113). [12]
- Deploy for competition mathematics with 96.83% on LiveBench Mathematics (#3 of 59) and perfect 100% on OTIS Mock AIME 2024-2025. [13,14]

**Watch out for:**
- Expect weaker human preference rankings on math-specific prompts: it places #34 of 148 on LMArena's maths category with Elo 1470, far below top performers. [15]

## 5. Claude Sonnet 5.5
https://modelmatchbook.com/models/anthropic/claude-sonnet-5.5-20260928

Claude Sonnet 5.5 scores 100% on OTIS Mock AIME 2024-2025, 95.6% on GPQA Diamond (#3 of 113), and 96.13% on LiveBench Mathematics (#7 of 59), offering strong graduate science and competition math performance.

**Best when:** Use for graduate-level science questions where it scores 95.6% on GPQA Diamond (#3 of 113). [16]

**More tips:**
- Deploy for competition mathematics with perfect 100% on OTIS Mock AIME 2024-2025. [17]

**Watch out for:**
- Note it ranks #12 of 148 on LMArena's maths category with Elo 1499, below several alternatives for human-preferred math responses. [18]

## 6. GPT-6 Astra
https://modelmatchbook.com/models/openai/gpt-6-astra-20260903

GPT-6 Astra leads LiveBench Reasoning at 92.65% (#1 of 59), ties for #1 on FrontierMath research mathematics at 93.7%, and scores 95.8% on GPQA Diamond (#2 of 113) with perfect 100% on OTIS Mock AIME.

**Best when:** Select for reasoning tasks where it scores 92.65% on LiveBench Reasoning (#1 of 59). [19]

**More tips:**
- Use for research-level mathematics with 93.7% on FrontierMath tiers 1 to 3 (#1 of 73, tied). [20]
- Deploy for graduate-level science with 95.8% on GPQA Diamond (#2 of 113). [21]

**Watch out for:**
- Expect lower human preference on math prompts: it ranks #40 of 148 on LMArena's maths category with Elo 1465. [22]

## 7. Muse Spark 1.3
https://modelmatchbook.com/models/meta/muse-spark-1.3-20260902

Muse Spark 1.3 scores 95.95% on LiveBench Mathematics (#9 of 59) and ranks #9 on LMArena overall text arena with Elo 1494, though it solves only 74.4% of FrontierMath tiers 1 to 3.

**Best when:** Use for competition mathematics with 95.95% on LiveBench Mathematics (#9 of 59). [23]

**Watch out for:**
- Note limited research-level mathematics depth: it solves 74.4% of FrontierMath tiers 1 to 3 (#18 of 73), below top performers. [24]

## 8. GPT-5.6 Terra
https://modelmatchbook.com/models/openai/gpt-5.6-terra-20260709

GPT-5.6 Terra scores 90.63% on LiveBench Reasoning (#9 of 59), an objective, ground-truth-scored evaluation refreshed with new questions.

**Best when:** Its strongest result for this task is on LiveBench Reasoning, which measures multi-step reasoning. [25]

## FAQ

**What is the best model for Math & Reasoning?**

Claude Fable 5.1 ranks first as of October 20, 2026. Claude Fable 5.1 scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics. [1]

**What is the best alternative to Claude Fable 5.1?**

Claude Opus 5.5 ranks second. Claude Opus 5.5 leads LiveBench Mathematics at 97.08% (#1 of 59), ranks #1 on LMArena instruction-following (Elo 1536), and solves 91.2% of FrontierMath tiers 1 to 3 for research-level mathematics. [2,3,4]

## Sources
1. "Within the 113 catalog models matched to this evaluation: Scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics." (OTIS Mock AIME (Epoch AI), https://epoch.ai/benchmarks)
2. "Within the 59 catalog models matched to this evaluation: Scores 97.08% on LiveBench Mathematics (#1 of 59), using objectively scored competition and olympiad-style tasks." (LiveBench Mathematics, https://livebench.ai/)
3. "Within the 152 catalog models matched to this evaluation: Ranks #1 of 152 on LMArena's instruction-following category (Elo 1536), based on blind human preference votes." (LMArena instruction-following category, https://lmarena.ai/leaderboard)
4. "Within the 73 catalog models matched to this evaluation: Solves 91.2% of FrontierMath tiers 1 to 3 in Epoch AI's independent run (#3 of 73), research-level mathematics." (FrontierMath Tiers 1-3 (Epoch AI), https://epoch.ai/benchmarks)
5. "Within the 113 catalog models matched to this evaluation: Scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics." (OTIS Mock AIME (Epoch AI), https://epoch.ai/benchmarks)
6. "Within the 113 catalog models matched to this evaluation: Scores 90.6% on GPQA Diamond in Epoch AI's independent run (#30 of 113), graduate-level science questions." (GPQA Diamond (Epoch AI), https://epoch.ai/benchmarks)
7. "Within the 148 catalog models matched to this evaluation: Ranks #1 of 148 on LMArena's maths category (Elo 1536), based on blind human preference votes for maths prompts." (LMArena maths category, https://lmarena.ai/leaderboard)
8. "Within the 113 catalog models matched to this evaluation: Scores 96.4% on GPQA Diamond in Epoch AI's independent run (#1 of 113), graduate-level science questions." (GPQA Diamond (Epoch AI), https://epoch.ai/benchmarks)
9. "Within the 113 catalog models matched to this evaluation: Scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics." (OTIS Mock AIME (Epoch AI), https://epoch.ai/benchmarks)
10. "Within the 73 catalog models matched to this evaluation: Solves 86% of FrontierMath tiers 1 to 3 in Epoch AI's independent run (#10 of 73), research-level mathematics." (FrontierMath Tiers 1-3 (Epoch AI), https://epoch.ai/benchmarks)
11. "Within the 73 catalog models matched to this evaluation: Solves 93.7% of FrontierMath tiers 1 to 3 in Epoch AI's independent run (#1 of 73), research-level mathematics." (FrontierMath Tiers 1-3 (Epoch AI), https://epoch.ai/benchmarks)
12. "Within the 113 catalog models matched to this evaluation: Scores 95.4% on GPQA Diamond in Epoch AI's independent run (#4 of 113), graduate-level science questions." (GPQA Diamond (Epoch AI), https://epoch.ai/benchmarks)
13. "Within the 59 catalog models matched to this evaluation: Scores 96.83% on LiveBench Mathematics (#3 of 59), using objectively scored competition and olympiad-style tasks." (LiveBench Mathematics, https://livebench.ai/)
14. "Within the 113 catalog models matched to this evaluation: Scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics." (OTIS Mock AIME (Epoch AI), https://epoch.ai/benchmarks)
15. "Within the 148 catalog models matched to this evaluation: Ranks #34 of 148 on LMArena's maths category (Elo 1470), based on blind human preference votes for maths prompts." (LMArena maths category, https://lmarena.ai/leaderboard)
16. "Within the 113 catalog models matched to this evaluation: Scores 95.6% on GPQA Diamond in Epoch AI's independent run (#3 of 113), graduate-level science questions." (GPQA Diamond (Epoch AI), https://epoch.ai/benchmarks)
17. "Within the 113 catalog models matched to this evaluation: Scores 100% on the OTIS Mock AIME 2024-2025 set in Epoch AI's independent run (#1 of 113), competition mathematics." (OTIS Mock AIME (Epoch AI), https://epoch.ai/benchmarks)
18. "Within the 148 catalog models matched to this evaluation: Ranks #12 of 148 on LMArena's maths category (Elo 1499), based on blind human preference votes for maths prompts." (LMArena maths category, https://lmarena.ai/leaderboard)
19. "Within the 59 catalog models matched to this evaluation: Scores 92.65% on LiveBench Reasoning (#1 of 59), an objective, ground-truth-scored evaluation refreshed with new questions." (LiveBench Reasoning, https://livebench.ai/)
20. "Within the 73 catalog models matched to this evaluation: Solves 93.7% of FrontierMath tiers 1 to 3 in Epoch AI's independent run (#1 of 73), research-level mathematics." (FrontierMath Tiers 1-3 (Epoch AI), https://epoch.ai/benchmarks)
21. "Within the 113 catalog models matched to this evaluation: Scores 95.8% on GPQA Diamond in Epoch AI's independent run (#2 of 113), graduate-level science questions." (GPQA Diamond (Epoch AI), https://epoch.ai/benchmarks)
22. "Within the 148 catalog models matched to this evaluation: Ranks #40 of 148 on LMArena's maths category (Elo 1465), based on blind human preference votes for maths prompts." (LMArena maths category, https://lmarena.ai/leaderboard)
23. "Within the 59 catalog models matched to this evaluation: Scores 95.95% on LiveBench Mathematics (#9 of 59), using objectively scored competition and olympiad-style tasks." (LiveBench Mathematics, https://livebench.ai/)
24. "Within the 73 catalog models matched to this evaluation: Solves 74.4% of FrontierMath tiers 1 to 3 in Epoch AI's independent run (#18 of 73), research-level mathematics." (FrontierMath Tiers 1-3 (Epoch AI), https://epoch.ai/benchmarks)
25. "Within the 59 catalog models matched to this evaluation: Scores 90.63% on LiveBench Reasoning (#9 of 59), an objective, ground-truth-scored evaluation refreshed with new questions." (LiveBench Reasoning, https://livebench.ai/)