Model comparison
Mistral Medium 3.5 128B vs o3-mini
Head-to-head evidence from 6 shared benchmark results across 3 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Mistral Medium 3.5 128B unranked (Not scored); o3-mini #141 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Mistral Medium 3.5 128B and o3-mini share 6 comparable benchmark results. 1 of 8 categories are comparable. 19 results are unique to Mistral Medium 3.5 128B; 4 to o3-mini.
Updated July 27, 2026- Shared results
- 6
- Mistral Medium 3.5 128B only
- 19
- o3-mini only
- 4
- Comparable categories
- 1 / 8
Treat this as a split decision. Mistral Medium 3.5 128B makes more sense if coding is the priority or you need the larger 256K context window; o3-mini is the better fit if you want the cheaper token bill.
Confidence note. This is a partial-evidence comparison with 6 shared benchmark results across 3 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
Mistral Medium 3.5 128B and o3-mini 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 $1.10 input / $4.40 output per 1M tokens for o3-mini. Mistral Medium 3.5 128B gives you the larger context window at 256K, compared with 200K for o3-mini.
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 | Mistral Medium 3.5 128B | Δ | o3-mini |
|---|---|---|---|
| Coding | Mistral Medium 3.5 128B77.6 | Margin← 28.3 | o3-mini49.3 |
| Knowledge | Mistral Medium 3.5 128BNot measured | MarginNo overlap | o3-mini77.2 |
| Inst. Following | Mistral Medium 3.5 128BNot measured | MarginNo overlap | o3-mini93.9 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
SWE-bench Verified
CodingA 77.6%B 49.3%Winner: Mistral Medium 3.5 128BΔ 28.3SWE-bench Verified: Mistral Medium 3.5 128B scored 77.6%; o3-mini scored 49.3%. 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 | Mistral Medium 3.5 128B | o3-mini | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Mistral Medium 3.5 128B$1.5 input / $7.5 output | o3-mini$1.1 input / $4.4 output | o3-mini has the lower combined listed price. |
| Generation speedtokens per second | Mistral Medium 3.5 128BNot available | o3-mini160 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Mistral Medium 3.5 128BNot available | o3-mini7.12 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Mistral Medium 3.5 128B256K | o3-mini200K | Mistral Medium 3.5 128B lists the larger context window. |
Benchmark Deep Dive
Agentic11 benchmarks
| Benchmark | Mistral Medium 3.5 128B | o3-mini | Result |
|---|---|---|---|
| τ³-bench resultsSource | 91.4% | — | Not comparable |
| AA Agentic IndexSource | 19.0% | — | Not comparable |
| τ²-bench resultsSource | 94.2% | 28.7% | Mistral Medium 3.5 128B leads |
| GDPval-AASource | 21.6% | — | Not comparable |
| GDPval-AASource | 933 | — | Not comparable |
| Gert LabsSource | 39.10% | — | 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 wins3 benchmarks
Reasoning2 benchmarks
Knowledge9 benchmarks
| Benchmark | Mistral Medium 3.5 128B | o3-mini | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 29.9% | 19.0% | Mistral Medium 3.5 128B leads |
| AA-GPQA DiamondSource | 74.8% | 74.8% | Tie |
| AA-HLESource | 12.8% | 8.7% | Mistral Medium 3.5 128B leads |
| 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 |
| MMLUSource | — | 86.9% | Not comparable |
| GPQASource | — | 77.2% | Not comparable |
Math1 benchmarks
| Benchmark | Mistral Medium 3.5 128B | o3-mini | Result |
|---|---|---|---|
| AIME 2024Source | — | 87.3% | Not comparable |
Multimodal1 benchmarks
| Benchmark | Mistral Medium 3.5 128B | o3-mini | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 64.9% | — | Not comparable |
Frequently Asked Questions (2)
Which is better, Mistral Medium 3.5 128B or o3-mini?
Mistral Medium 3.5 128B and o3-mini 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, Mistral Medium 3.5 128B or o3-mini?
Mistral Medium 3.5 128B has the edge for coding in this comparison, averaging 77.6 versus 49.3. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
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