Model comparison
Claude Opus 4.5 vs Mistral Medium 3.5 128B
Head-to-head evidence from 15 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Opus 4.5 #39 (Supported); Mistral Medium 3.5 128B unranked (Not scored). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude Opus 4.5 and Mistral Medium 3.5 128B share 15 comparable benchmark results. 1 of 8 categories are comparable. 44 results are unique to Claude Opus 4.5; 10 to Mistral Medium 3.5 128B.
Updated July 27, 2026- Shared results
- 15
- Claude Opus 4.5 only
- 44
- Mistral Medium 3.5 128B only
- 10
- Comparable categories
- 1 / 8
Treat this as a split decision. Claude Opus 4.5 makes more sense if you would rather avoid the extra latency and token burn of a reasoning model; Mistral Medium 3.5 128B is the better fit if coding is the priority or you want the cheaper token bill.
Confidence note. This is a partial-evidence comparison with 15 shared benchmark results across 6 evidence categories; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
Claude Opus 4.5 and Mistral Medium 3.5 128B finish on the same BenchAlign overall score, so this is less about a single winner and more about where the edge shows up. The BenchAlign headline says tie; the benchmark table is where the real choice happens.
Claude Opus 4.5 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $1.50 input / $7.50 output per 1M tokens for Mistral Medium 3.5 128B. That is roughly 3.3x on output cost alone. Mistral Medium 3.5 128B is the reasoning model in the pair, while Claude Opus 4.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Mistral Medium 3.5 128B gives you the larger context window at 256K, compared with 200K for Claude Opus 4.5.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Claude Opus 4.5 | Δ | Mistral Medium 3.5 128B |
|---|---|---|---|
| Coding | Claude Opus 4.571.7 | Margin→ 5.9 | Mistral Medium 3.5 128B77.6 |
| Agentic | Claude Opus 4.562.6 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Reasoning | Claude Opus 4.564.4 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Knowledge | Claude Opus 4.558.1 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Math | Claude Opus 4.557.5 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Multilingual | Claude Opus 4.585.7 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Multimodal | Claude Opus 4.569.9 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Inst. Following | Claude Opus 4.569.5 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
SWE-bench Verified
CodingA 80.9%B 77.6%Winner: Claude Opus 4.5Δ 3.3SWE-bench Verified: Claude Opus 4.5 scored 80.9%; Mistral Medium 3.5 128B scored 77.6%. Claude Opus 4.5 wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Opus 4.5 | Mistral Medium 3.5 128B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Opus 4.5$5 input / $25 output | Mistral Medium 3.5 128B$1.5 input / $7.5 output | Mistral Medium 3.5 128B has the lower combined listed price. |
| Generation speedtokens per second | Claude Opus 4.546 tok/s | Mistral Medium 3.5 128BNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Opus 4.51.01 s | Mistral Medium 3.5 128BNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Opus 4.5200K | Mistral Medium 3.5 128B256K | Mistral Medium 3.5 128B lists the larger context window. |
Benchmark Deep Dive
Agentic24 benchmarks
| Benchmark | Claude Opus 4.5 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 59.3% | — | Not comparable |
| OSWorld-VerifiedSource | 66.3% | — | Not comparable |
| OSWorldSource | 66.3% | — | Not comparable |
| Claw-EvalSource | 59.6% | — | Not comparable |
| QwenClawBenchSource | 52.3% | — | Not comparable |
| τ³-bench resultsSource | 70.2% | 91.4% | Mistral Medium 3.5 128B leads |
| VITA-BenchSource | 23.3% | — | Not comparable |
| DeepPlanningSource | 26.4% | — | Not comparable |
| ToolathlonSource | 43.5% | — | Not comparable |
| MCP AtlasSource | 42.3% | — | Not comparable |
| MCP-TasksSource | 71.8% | — | Not comparable |
| WideResearchSource | 76.4% | — | Not comparable |
| CyberGymSource | 50.6% | — | Not comparable |
| τ²-bench resultsSource | 86.3% | 94.2% | Mistral Medium 3.5 128B leads |
| Gert LabsSource | 64.23% | 39.10% | Claude Opus 4.5 leads |
| JobBenchSource | 32.3% | — | Not comparable |
| AA Agentic IndexSource | — | 19.0% | Not comparable |
| GDPval-AASource | — | 21.6% | Not comparable |
| GDPval-AASource | — | 933 | Not comparable |
| AA EnterpriseOps-GymSource | — | 33.7% | Not comparable |
| AA Harvey LABSource | — | 69.1% | Not comparable |
| terminalBenchHardSource | — | 33.3% | Not comparable |
| AA BriefcaseSource | — | 516 | Not comparable |
| AA Tau3 BankingSource | — | 14.4% | Not comparable |
CodingMistral Medium 3.5 128B wins7 benchmarks
| Benchmark | Claude Opus 4.5 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| SWE-bench VerifiedSource | 80.9% | 77.6% | Claude Opus 4.5 leads |
| LiveCodeBench v6Source | 84.8% | — | Not comparable |
| SWE-bench ProSource | 57.1% | — | Not comparable |
| SWE MultilingualSource | 77.5% | — | Not comparable |
| NL2RepoSource | 43.2% | — | Not comparable |
| AA-SciCodeSource | 47.0% | 39.6% | Claude Opus 4.5 leads |
| AA Coding IndexSource | — | 46.9% | Not comparable |
Reasoning4 benchmarks
Knowledge14 benchmarks
| Benchmark | Claude Opus 4.5 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| GPQASource | 87% | — | Not comparable |
| SuperGPQASource | 70.6% | — | Not comparable |
| MMLU-ProSource | 89.5% | — | Not comparable |
| MMLU-ReduxSource | 96.6% | — | Not comparable |
| C-EvalSource | 92.2% | — | Not comparable |
| HLESource | 30.8% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | 34.7% | 29.9% | Claude Opus 4.5 leads |
| AA-GPQA DiamondSource | 81.0% | 74.8% | Claude Opus 4.5 leads |
| AA-HLESource | 12.9% | 12.8% | Claude Opus 4.5 leads |
| AA-Omniscience IndexSource | -3.9% | -36.3% | Claude Opus 4.5 leads |
| AA-Omniscience AccuracySource | 40.7% | 25.1% | Claude Opus 4.5 leads |
| AA-Omniscience Hallucination RateSource | 75.4% | 82.0% | Claude Opus 4.5 leads |
| AA MMLU-ProSource | 88.9% | — | Not comparable |
| AA Openness IndexSource | — | 33.3% | Not comparable |
Math7 benchmarks
| Benchmark | Claude Opus 4.5 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| AIME26Source | 95.1% | — | Not comparable |
| HMMT Feb 2025Source | 92.9% | — | Not comparable |
| HMMT Nov 2025Source | 93.3% | — | Not comparable |
| HMMT Feb 2026Source | 85.3% | — | Not comparable |
| MMAnswerBenchSource | 84.0% | — | Not comparable |
| FrontierMath v2 (Tiers 1-3)Source | 20.690% | — | Not comparable |
| FrontierMath v2 (Tier 4)Source | 4.167% | — | Not comparable |
Multilingual2 benchmarks
Multimodal8 benchmarks
| Benchmark | Claude Opus 4.5 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| MMMU-ProSource | 70.6% | — | Not comparable |
| MathVisionSource | 74.3% | — | Not comparable |
| CharXivSource | 68.5% | — | Not comparable |
| VideoMMMUSource | 84.4% | — | Not comparable |
| ScreenSpot ProSource | 45.7% | — | Not comparable |
| V*Source | 67.0% | — | Not comparable |
| AA-MMMU-ProSource | 71.2% | 64.9% | Claude Opus 4.5 leads |
| Design Arena WebsiteSource | 1272 | — | Not comparable |
Frequently Asked Questions (2)
Which is better, Claude Opus 4.5 or Mistral Medium 3.5 128B?
Claude Opus 4.5 and Mistral Medium 3.5 128B are tied on the BenchAlign overall score, so the right pick depends on which category matters most for your use case.
Which is better for coding, Claude Opus 4.5 or Mistral Medium 3.5 128B?
Mistral Medium 3.5 128B has the edge for coding in this comparison, averaging 77.6 versus 71.7. Inside this category, AA-SciCode is the benchmark that creates the most daylight between them.
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