Mistral Small 3 vs o3 Pro
Updated October 21, 2026. 2 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
Neither model has a coding score yet, so the two cannot be ranked on coding.
Mistral Small 3 has the edge where output tokens cost 1000.0x less, and where what matters is AA Intelligence Index or GPQA Diamond (Artificial Analysis run), where it leads.
- Shared results
- 2
- Mistral Small 3 only
- 34
- o3 Pro only
- 9
- Like-for-like categories
- 2 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Neither has a coding score yet.
One side not measured
Intelligence
AA Intelligence Index
o3 Pro
o3 Pro leads, 21.9 against 6.7.
Same board, both measured
Long documents
Listed context window
o3 Pro
o3 Pro takes 200K tokens against 33K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mistral Small 3
Mistral Small 3 $0.0001, o3 Pro $0.060 per turn.
List prices
At a glance
- Coding index
- Mistral Small 3 not benchmarked, o3 Pro not benchmarked.
- Widest category
- Reasoning, 38.3 points apart on average over 1 shared benchmark.
- Widest single gap
- GPQA Diamond (Artificial Analysis run): Mistral Small 3 46.2% against o3 Pro 84.5%, 38.3 points apart on a 0 to 100 scale.
- Output price
- Mistral Small 3 $0.08 against o3 Pro $80.00 per million output tokens, 1000.0x apart.
- Context window
- Mistral Small 3 takes 33K tokens, o3 Pro 200K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Mistral Small 3 | Bars | o3 Pro | Ties |
|---|---|---|---|---|
| Intelligence | 0 | 1 | ||
| Reasoning | 0 | 1 | ||
| All shared boards | 0 | 2 |
CodingDirectional onlySix of these boards feed the Vibe Coding Index5 boards, none shared
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| Aider polyglot | Not measured | 84.9% | Only o3 Pro measured |
| LiveCodeBench (Artificial Analysis run) | 25.2% | Not measured | Only Mistral Small 3 measured |
| WeirdML | Not measured | 58.2% | Only o3 Pro measured |
| LMArena Text: coding | 1246 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: software and IT | 1248 | Not measured | Only Mistral Small 3 measured |
| Neither model has a result on the other 33 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| AA Intelligence Index | 6.7 | 21.9 | o3 Pro |
| Epoch Capabilities Index | Not measured | 147.3 | Only o3 Pro measured |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| τ²-Bench Telecom | 19.6% | Not measured | Only Mistral Small 3 measured |
| Neither model has a result on the other 38 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| GPQA Diamond (Artificial Analysis run) | 46.2% | 84.5% | o3 Pro |
| Humanity's Last Exam (Artificial Analysis run) | 3.8% | Not measured | Only Mistral Small 3 measured |
| ARC-AGI | Not measured | 59.3% | Only o3 Pro measured |
| ARC-AGI-2 | Not measured | 4.9% | Only o3 Pro measured |
| LMArena Text: hard prompts | 1233 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: expert | 1202 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: hard prompts in English | 1243 | Not measured | Only Mistral Small 3 measured |
| Neither model has a result on the other 14 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index4 boards, none shared
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| AA Math Index | 4.3 | Not measured | Only Mistral Small 3 measured |
| AIME 2025 (Artificial Analysis run) | 4.3% | Not measured | Only Mistral Small 3 measured |
| LMArena Text: math | 1240 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: mathematical work | 1243 | Not measured | Only Mistral Small 3 measured |
| Neither model has a result on the other 9 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index5 boards, none shared
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| MMLU Pro (Artificial Analysis run) | 65.2% | Not measured | Only Mistral Small 3 measured |
| LMArena Text: science | 1235 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: medicine and healthcare | 1215 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: legal and government | 1219 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: business and finance | 1205 | Not measured | Only Mistral Small 3 measured |
| Neither model has a result on the other 12 boards here | |||
Web designNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| Neither model has a result on 9 boards here | |||
GeneralDirectional onlyPublic boards, shown as published, kept out of the index21 boards, none shared
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| IFBench | 26.4% | Not measured | Only Mistral Small 3 measured |
| Long context reasoning (AA-LCR) | 0.0% | Not measured | Only Mistral Small 3 measured |
| DTBench | Not measured | 86.9% | Only o3 Pro measured |
| LMCA | Not measured | 38.5% | Only o3 Pro measured |
| Fiction.LiveBench | Not measured | 97.2% | Only o3 Pro measured |
| Creative writing (Lech Mazur) | Not measured | 84.4% | Only o3 Pro measured |
| LMArena Text | 1234 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: instruction following | 1214 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: creative writing | 1194 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: English | 1256 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: non-English | 1198 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: Chinese | 1204 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: German | 1211 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: Japanese | 1111 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: Korean | 1188 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: French | 1204 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: Russian | 1216 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: multi-turn | 1217 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: longer queries | 1246 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: writing and language | 1214 | Not measured | Only Mistral Small 3 measured |
| LMArena Text: entertainment and media | 1184 | Not measured | Only Mistral Small 3 measured |
| Neither model has a result on the other 25 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Mistral Small 3 | o3 Pro | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Mistral Small 3 costs less
Repository review
50K input + 3K output tokens
Mistral Small 3 costs less
Agent loop
200K input + 10K output tokens
Mistral Small 3 costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Mistral Small 3 | OpenAI o3 Pro |
|---|---|---|
| Maker | Mistral AI | OpenAI |
| Weights | Open weights | No public weights listed |
| Released | January 30, 2025 | June 10, 2025 |
| Context window | 33K | 200K |
| Input $/Mtok | $0.05 | $20.00 |
| Output $/Mtok | $0.08 | $80.00 |
| Coding index | Not benchmarked | Not benchmarked |
| Independent measurements behind it | 0 | 0 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Mistral Small 3 better than o3 Pro for coding?
Neither model has a coding score yet, so the two cannot be ranked on coding. Mistral Small 3 has the edge where output tokens cost 1000.0x less, and where what matters is AA Intelligence Index or GPQA Diamond (Artificial Analysis run), where it leads.
Which is cheaper, Mistral Small 3 or o3 Pro?
Mistral Small 3 costs $0.05 per million input tokens and $0.08 per million output tokens; o3 Pro costs $20.00 and $80.00. Cost per solved task is known for neither of them.
Which has the bigger context window, Mistral Small 3 or o3 Pro?
o3 Pro, with 200K tokens against 33K.
How many benchmarks is the Mistral Small 3 vs o3 Pro comparison based on?
2 benchmarks have a result for both models as of October 21, 2026. Mistral Small 3's coding index rests on 0 independent benchmarks and o3 Pro's on 0. Where only one model has a result, the page says so instead of naming a winner.