Model comparison
Grok 4.20 vs Mistral Medium 3.5 128B
Head-to-head evidence from 2 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Grok 4.20 #93 (Estimated); Mistral Medium 3.5 128B unranked (Not scored). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Grok 4.20 and Mistral Medium 3.5 128B share 2 comparable benchmark results. 1 of 8 categories are comparable. 17 results are unique to Grok 4.20; 23 to Mistral Medium 3.5 128B.
Updated July 27, 2026- Shared results
- 2
- Grok 4.20 only
- 17
- Mistral Medium 3.5 128B only
- 23
- Comparable categories
- 1 / 8
Treat this as a split decision. Grok 4.20 makes more sense if you want the cheaper token bill or you need the larger 2M context window; Mistral Medium 3.5 128B is the better fit if coding is the priority.
Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 2 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
Grok 4.20 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.
Mistral Medium 3.5 128B is also the more expensive model on tokens at $1.50 input / $7.50 output per 1M tokens, versus $2.00 input / $6.00 output per 1M tokens for Grok 4.20. Grok 4.20 gives you the larger context window at 2M, compared with 256K for Mistral Medium 3.5 128B.
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 | Grok 4.20 | Δ | Mistral Medium 3.5 128B |
|---|---|---|---|
| Coding | Grok 4.2067.1 | Margin→ 10.5 | Mistral Medium 3.5 128B77.6 |
| Agentic | Grok 4.2047.1 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Reasoning | Grok 4.2053.3 | MarginNo overlap | Mistral Medium 3.5 128BNot measured |
| Multimodal | Grok 4.2070.1 | 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 76.7%B 77.6%Winner: Mistral Medium 3.5 128BΔ 0.9SWE-bench Verified: Grok 4.20 scored 76.7%; Mistral Medium 3.5 128B scored 77.6%. Mistral Medium 3.5 128B wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Grok 4.20 | Mistral Medium 3.5 128B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Grok 4.20$2 input / $6 output | Mistral Medium 3.5 128B$1.5 input / $7.5 output | Grok 4.20 has the lower combined listed price. |
| Generation speedtokens per second | Grok 4.20233 tok/s | Mistral Medium 3.5 128BNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Grok 4.2010.33 s | Mistral Medium 3.5 128BNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Grok 4.202M | Mistral Medium 3.5 128B256K | Grok 4.20 lists the larger context window. |
Benchmark Deep Dive
Agentic13 benchmarks
| Benchmark | Grok 4.20 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 47.1% | — | Not comparable |
| DeepSearchQASource | 62.8% | — | Not comparable |
| Gert LabsSource | 38.36% | 39.10% | Mistral Medium 3.5 128B leads |
| τ³-bench resultsSource | — | 91.4% | Not comparable |
| AA Agentic IndexSource | — | 19.0% | Not comparable |
| τ²-bench resultsSource | — | 94.2% | 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 wins6 benchmarks
| Benchmark | Grok 4.20 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| LiveCodeBench ProSource | 74.2% | — | Not comparable |
| SWE-bench VerifiedSource | 76.7% | 77.6% | Mistral Medium 3.5 128B leads |
| SWE-bench ProSource | 51.8% | — | Not comparable |
| Vibe Code BenchSource | 4.06% | — | Not comparable |
| AA Coding IndexSource | — | 46.9% | Not comparable |
| AA-SciCodeSource | — | 39.6% | Not comparable |
Reasoning4 benchmarks
Knowledge11 benchmarks
| Benchmark | Grok 4.20 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| GPQA-DSource | 88.5% | — | Not comparable |
| HLE w/o toolsSource | 31.6% | — | Not comparable |
| HealthBench HardSource | 20.3% | — | Not comparable |
| MedXpertQA (Text)Source | 50.2% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 29.9% | Not comparable |
| AA-GPQA DiamondSource | — | 74.8% | Not comparable |
| AA-HLESource | — | 12.8% | Not comparable |
| AA-Omniscience IndexSource | — | -36.3% | Not comparable |
| AA-Omniscience AccuracySource | — | 25.1% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 82.0% | Not comparable |
| AA Openness IndexSource | — | 33.3% | Not comparable |
Multimodal7 benchmarks
| Benchmark | Grok 4.20 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| MMMU-ProSource | 75.2% | — | Not comparable |
| CharXivSource | 60.9% | — | Not comparable |
| ERQASource | 54.1% | — | Not comparable |
| SimpleVQASource | 57.4% | — | Not comparable |
| MedXpertQA (MM)Source | 65.8% | — | Not comparable |
| Design Arena WebsiteSource | 1252 | — | Not comparable |
| AA-MMMU-ProSource | — | 64.9% | Not comparable |
Inst. Following1 benchmarks
| Benchmark | Grok 4.20 | Mistral Medium 3.5 128B | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 68.8% | Not comparable |
Frequently Asked Questions (2)
Which is better, Grok 4.20 or Mistral Medium 3.5 128B?
Grok 4.20 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, Grok 4.20 or Mistral Medium 3.5 128B?
Mistral Medium 3.5 128B has the edge for coding in this comparison, averaging 77.6 versus 67.1. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
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