Model comparison
Claude Sonnet 5.5 vs GPT-5 Nano
Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 33.4 on the Noometry Index. GPT-5 Nano costs 29× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Last verified . 8 shared benchmarks.
Summary
- They share 8 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 6 categories and GPT-5 Nano in 0 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 88.7 to 29.1.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Sonnet 5.5 and 12% for GPT-5 Nano.
- GPT-5 Nano is cheaper at $0.05 / $0.40 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 400K.
Side by side
| Claude Sonnet 5.5 | GPT-5 Nano | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 60.5 | 33.4 |
| Released | 2026-09-28 | 2025-08-07 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $2 | $0.05 |
| Output $ / M tokens | $10 | $0.40 |
| Results tracked | 16 | 48 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 65.5 (#6), GPT-5 Nano: 33.3 (#248)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| ALE-Bench | 1,819 | 718.67 |
| FrontierCode | 52.1% | — |
| SWE-bench Verified (bash only) | — | 34.8% |
| CursorBench | 55.5% | — |
| LMArena WebDev | 1699 | — |
| FrontierSWE | 61.9% | — |
| SciCode | 61% | — |
| WeirdML | — | 38.1% |
| LMArena Coding | — | 1351 |
Agentic & Tool Use Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 44.9 (#14), GPT-5 Nano: 25.6 (#99)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| Terminal-Bench | — | 21.8% |
| APEX-Agents | 75.5% | — |
| Berkeley Function Calling Leaderboard | — | 51.5% |
Reasoning Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 52.4 (#29), GPT-5 Nano: 16.4 (#291)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| Mystery Game Puzzles | 65% | 9% |
| ARC-AGI-2 | — | 2.6% |
| Kagi LLM Benchmark | — | 62.2% |
| ARC-AGI-1 | — | 20.7% |
| CritPt | 31.4% | — |
| Chess Puzzles | — | 27% |
| LMArena Hard Prompts | — | 1329 |
| DTBench | — | 62.7% |
| LMCA | — | 7.9% |
| Epoch Capabilities Index | — | 139.39 |
| ForecastBench | — | 59.1 |
Math Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 88.7 (#4), GPT-5 Nano: 29.1 (#221)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | 20% |
| FrontierMath Tier 4 | 80.5% | 2.4% |
| OTIS Mock AIME 2024-2025 | 100% | 81.1% |
| ProofBench | 100% | 12% |
| Omni-MATH | — | 54.6% |
| LMArena Math | — | 1318 |
| MATH Level 5 | — | 95.2% |
| FrontierMath (Feb 2025 set) | — | 8.3% |
| FrontierMath Tier 4 (v1) | — | 2.1% |
Knowledge Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#11), GPT-5 Nano: 35.8 (#166)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| GPQA Diamond | 95.6% | 69.4% |
| SimpleQA Verified | 46.5% | 11.7% |
| MMLU-Pro | — | 77.8% |
| Vectara Hallucination Rate | — | 10.5% |
| GPQA (HELM) | — | 67.9% |
| LMArena Expert | — | 1321 |
Multimodal Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 53.2 (#5), GPT-5 Nano: 30.7 (#102)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| LMArena Vision | — | 1159 |
| VPCT | — | 37.2% |
| Furniture Assembly | 75% | — |
Multilingual Not comparable
Claude Sonnet 5.5: —, GPT-5 Nano: 45.5 (#167)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| LMArena Non-English | — | 1313 |
| LMArena Chinese | — | 1355 |
| LMArena German | — | 1329 |
| LMArena Korean | — | 1269 |
| LMArena Russian | — | 1296 |
| LMArena Spanish | — | 1360 |
Instruction Following Not comparable
Claude Sonnet 5.5: —, GPT-5 Nano: 75.2 (#72)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| IFEval | — | 93.2% |
| LMArena Instruction Following | — | 1306 |
Long Context Not comparable
Claude Sonnet 5.5: —, GPT-5 Nano: 31.3 (#275)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| Fiction.LiveBench | — | 44.4% |
| LMArena Longer Query | — | 1313 |
Writing & Preference Not comparable
Claude Sonnet 5.5: —, GPT-5 Nano: 39.4 (#244)
| Benchmark | Claude Sonnet 5.5 | GPT-5 Nano |
|---|---|---|
| LMArena Text | — | 1320 |
| LMArena Creative Writing | — | 1250 |
| EQ-Bench Creative Writing | — | 705 |
| WildBench | — | 80.6% |
| LMArena Multi-Turn | — | 1311 |
Frequently asked questions
Is Claude Sonnet 5.5 better than GPT-5 Nano?
Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 33.4 on the Noometry Index. GPT-5 Nano costs 29× 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 GPT-5 Nano?
GPT-5 Nano is cheaper. It lists at $0.05 per million input tokens and $0.40 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.
Is Claude Sonnet 5.5 or GPT-5 Nano better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 65.5 versus 33.3 in the Noometry coding category.
Which has the bigger context window?
Claude Sonnet 5.5 does, with 1M tokens against 400K.
How many benchmarks do Claude Sonnet 5.5 and GPT-5 Nano share?
8 benchmarks have published results for both models. Claude Sonnet 5.5 has 16 scored results on Noometry and GPT-5 Nano has 48.