Model comparison
Claude Sonnet 5.5 vs o3-mini
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 36.7 on the Noometry Index. o3-mini costs 2.1× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Last verified . 21 shared benchmarks.
Summary
- They share 21 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 9 categories and o3-mini in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 28.1.
- The biggest single-benchmark swing is FrontierMath Tier 4: 80.5% for Claude Sonnet 5.5 and 0% for o3-mini.
- o3-mini is cheaper at $1.10 / $4.40 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 200K.
Side by side
| Claude Sonnet 5.5 | o3-mini | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 61.9 | 36.7 |
| Released | 2026-09-28 | 2024-12-20 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 200K |
| Max output | 128K | 100K |
| Input $ / M tokens | $2 | $1.10 |
| Output $ / M tokens | $10 | $4.40 |
| Results tracked | 32 | 51 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 67.3 (#6), o3-mini: 40.8 (#132)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| SciCode | 61% | 39.8% |
| LMArena Coding | 1513 | 1378 |
| FrontierCode | 52.1% | — |
| Aider Polyglot | — | 60.4% |
| CursorBench | 55.5% | — |
| LMArena WebDev | 1774 | — |
| FrontierSWE | 61.9% | — |
| GSO | — | 1.3% |
| WeirdML | — | 43.7% |
| LiveBench Coding | — | 82.7% |
| CadEval | — | 54% |
| ALE-Bench | 1,819 | — |
Agentic & Tool Use Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 45.0 (#16), o3-mini: 29.6 (#84)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| APEX-Agents | 75.5% | — |
| Cybench | — | 22.5% |
Reasoning Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 54.0 (#28), o3-mini: 16.3 (#305)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| CritPt | 31.4% | 0.3% |
| LMArena Hard Prompts | 1495 | 1366 |
| Mystery Game Puzzles | 65% | 7% |
| Epoch Capabilities Index | 165.03 | 140.34 |
| ARC-AGI-2 | — | 3% |
| SimpleBench | — | 22.8% |
| NYT Connections (extended) | 80.5% | — |
| ARC-AGI-1 | — | 34.5% |
| Chess Puzzles | — | 17% |
| LiveBench Reasoning | — | 89.6% |
| DTBench | — | 68.8% |
| LiveBench Data Analysis | — | 70.6% |
| LMCA | — | 19% |
| ForecastBench | — | 59.6 |
| LiveBench | — | 75.9% |
Math Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 87.9 (#6), o3-mini: 28.1 (#244)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | 18.6% |
| FrontierMath Tier 4 | 80.5% | 0% |
| OTIS Mock AIME 2024-2025 | 100% | 76.9% |
| LMArena Math | 1510 | 1396 |
| ProofBench | 100% | — |
| LiveBench Math | — | 77.3% |
| MATH Level 5 | — | 96.5% |
| FrontierMath (Feb 2025 set) | — | 12.4% |
| FrontierMath Erdős | 2.9% | — |
| FrontierMath Tier 4 (v1) | — | 4.2% |
Knowledge Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#12), o3-mini: 38.3 (#146)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| GPQA Diamond | 95.6% | 77% |
| SimpleQA Verified | 46.5% | 15.3% |
| LMArena Expert | 1540 | 1364 |
| Confabulations | — | 17.9% |
Multimodal Not comparable
Claude Sonnet 5.5: 51.5 (#6), o3-mini: —
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| LMArena Vision | 1289 | — |
| Furniture Assembly | 75% | — |
Multilingual Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 55.3 (#30), o3-mini: 45.7 (#164)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| LMArena Non-English | 1452 | 1319 |
| LMArena Chinese | 1522 | 1379 |
| LMArena Russian | 1451 | 1304 |
| LMArena French | — | 1334 |
| LMArena German | — | 1303 |
| LMArena Japanese | — | 1286 |
| LMArena Korean | — | 1314 |
| LMArena Spanish | — | 1321 |
Instruction Following Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 78.3 (#11), o3-mini: 75.1 (#72)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| LMArena Instruction Following | 1495 | 1337 |
| LiveBench Instruction Following | — | 84.4% |
Long Context Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 45.9 (#28), o3-mini: 33.8 (#256)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| LMArena Longer Query | 1498 | 1343 |
| Fiction.LiveBench | — | 50% |
Writing & Preference Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#40), o3-mini: 50.3 (#182)
| Benchmark | Claude Sonnet 5.5 | o3-mini |
|---|---|---|
| LMArena Text | 1471 | 1337 |
| LMArena Creative Writing | 1465 | 1286 |
| LMArena Multi-Turn | 1474 | 1320 |
| Short-Story Creative Writing | — | 61.7% |
| LiveBench Language | — | 50.7% |
Frequently asked questions
Is Claude Sonnet 5.5 better than o3-mini?
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 36.7 on the Noometry Index. o3-mini costs 2.1× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Sonnet 5.5 or o3-mini?
o3-mini is cheaper. It lists at $1.10 per million input tokens and $4.40 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.
Is Claude Sonnet 5.5 or o3-mini better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 40.8 in the Noometry coding category.
Which has the bigger context window?
Claude Sonnet 5.5 does, with 1M tokens against 200K.
How many benchmarks do Claude Sonnet 5.5 and o3-mini share?
21 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and o3-mini has 51.