Compare / Claude Sonnet 5.5 vs Mistral Small 4
Claude Sonnet 5.5 vs Mistral Small 4
Which is cheaper, which is more capable, and which does better at each kind of work, from 12 results on 2 sources that measured both models.
Results as of 8 October 2026 (catalogue release 2026-10-08-4199ce0620fe).
Claude Sonnet 5.5 or Mistral Small 4? The short answer
Pick Claude Sonnet 5.5 if quality matters most: it scores higher (Intelligence Index 56.0 against 11.3). Pick Mistral Small 4 if cost matters more: it costs 15 times less per token.
- Mistral Small 4 is cheaper: $0.26 against $4.00 per million tokens, 15 times less.
- Claude Sonnet 5.5 scores higher on the Artificial Analysis Intelligence Index: 56.0 against 11.3.
- Claude Sonnet 5.5 is newer: released 28 Sep 2026, against 16 Mar 2026 for Mistral Small 4.
- On our own benchmarks, on the results both models have: Mistral Small 4 does better for speed under pressure.
- On third-party benchmarks, on the results both models have: Claude Sonnet 5.5 does better for agents and tool use and reasoning and knowledge.
At a glance
| Claude Sonnet 5.5 | Mistral Small 4 | |
|---|---|---|
| Price per million tokens | $2.00 in · $10.00 out | $0.15 in · $0.60 out |
| Blended (3 in : 1 out) | $4.00 | $0.26 |
| Cheapest host, blended | $4.00 (Amazon Bedrock) | $0.26 (Mistral) |
| Cached input, per million | $0.20 cached input | $0.015 cached input |
| Intelligence Index | 56.0 | 11.3 |
| Spring Prompt overall | 64 | – |
| Output speed, tokens a second | 134 | 164 |
| Context window | 1,000,000 tokens | 262,144 tokens |
| Released | 28 Sep 2026 (newer) | 16 Mar 2026 |
| Weights | Closed | Open |
| Developer based in | the US | France |
Prices are the developer's list price where we have read it, otherwise the typical host on OpenRouter; see every model's price. Intelligence and speed from Artificial Analysis.
Which is better for what
Each model's rank among models available today, for each kind of work, from our own benchmarks and licensed sources. The better rank is in green.
| Use case | Claude Sonnet 5.5 | Mistral Small 4 |
|---|---|---|
| Product listingsTurning a sparse product feed and photos into listings that can go live | 10 of 20 | not measured |
| Decks from an analysisTurning a finished analysis into a deck you could present as it is | 4 of 19 | not measured |
| Marketing planningPlanning a year of ad spend without overspending | 4 of 19 | not measured |
| Agents and tool useMulti-step tasks with tools: support desks, coding agents, function calls | 1 of 164 | 132 of 164 |
| Professional workReal tasks from banking, consulting and law, business documents and freelance projects | 1 of 51 | not measured |
| Reasoning and knowledgeHard questions across science, maths and general knowledge | 2 of 198 | 131 of 198 |
| WritingWhat people prefer in blind comparisons, and judged writing quality | 32 of 188 | 116 of 188 |
| Sticking to the factsSummarising without inventing things, and factual answers | 42 of 152 | not measured |
| Speed under pressureGood decisions against a real clock (fast chess) | 22 of 22 | 9 of 22 |
From our research
Every shared result
Each model's best result on every measure both have, grouped by benchmark, with the setting that produced it. The headline measures of each benchmark come first; the rest are under "Show all". Green marks the better value; where a source reports ranges that overlap, neither is marked.
| Measure | Claude Sonnet 5.5 | Mistral Small 4 |
|---|---|---|
| BulletBench measured by Spring Prompt · 3 results | ||
| Ladder Elo · Lightning 10+1ladder Elo, higher is better | 33low reasoning | 571no reasoning |
| Cost per game · Lightning 10+1US dollars, lower is better | $0.0080low reasoning | $0.0041no reasoning |
| Games lost on time · Lightning 10+1% of games, lower is better | 91.7%low reasoning | 0.0%no reasoning |
| Artificial Analysis reported by Artificial Analysis · 3 results | ||
| Artificial Analysis Intelligence Indexindex score, higher is better | 56.0max reasoning | 11.3 |
| Humanity's Last Exam% of questions, higher is better | 55.0%max reasoning | 9.9% |
| Terminal-Bench 4.0% of tasks, higher is better | 63.6%max reasoning | 0.0% |
Show all 12 results (6 more)
| Measure | Claude Sonnet 5.5 | Mistral Small 4 |
|---|---|---|
| BulletBench measured by Spring Prompt · 2 results | ||
| Invalid moves · Lightning 10+1% of moves, lower is better | 0.0%low reasoning | 1.0%no reasoning |
| Median move time · Lightning 10+1milliseconds, lower is better | 2.1 slow reasoning | 0.6 sno reasoning |
| Artificial Analysis reported by Artificial Analysis · 4 results | ||
| Long-context reasoning (AA-LCR)% of questions, higher is better | 82.7%max reasoning | 49.7% |
| Output speedtokens per second, higher is better | 134max reasoning | 164 |
| SciCode% of problems, higher is better | 61.0%max reasoning | 38.8% |
| Time to first answer tokenseconds, lower is better | 0.76medium reasoning | 0.47no reasoning |
Quick answers
Is Claude Sonnet 5.5 better than Mistral Small 4?
Pick Claude Sonnet 5.5 if quality matters most: it scores higher (Intelligence Index 56.0 against 11.3). Pick Mistral Small 4 if cost matters more: it costs 15 times less per token.
Which is cheaper, Claude Sonnet 5.5 or Mistral Small 4?
Mistral Small 4 is cheaper: $0.26 against $4.00 per million tokens, 15 times less.
Which is faster, Claude Sonnet 5.5 or Mistral Small 4?
Mistral Small 4 writes about 164 tokens a second on its usual API, against 134 for Claude Sonnet 5.5 (Artificial Analysis).
Run Claude Sonnet 5.5 and Mistral Small 4 on your own prompt
Benchmarks aren't your data. Try both side by side in the playground, with the cost of every answer.