Model comparison
Claude Sonnet 4.5 vs GPT-5.3 Chat
Claude Sonnet 4.5 is the stronger model overall, scoring 44.0 to 42.1 on the Noometry Index.
Last verified . 18 shared benchmarks.
Summary
- They share 18 benchmarks with published results for both. Claude Sonnet 4.5 scores higher in 6 categories and GPT-5.3 Chat in 2 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Claude Sonnet 4.5 leads 48.4 to 38.2.
- GPT-5.3 Chat is cheaper at $1.75 / $14 per million input/output tokens, against $3 / $15 for Claude Sonnet 4.5.
- Claude Sonnet 4.5 accepts more context: 1M tokens versus 128K.
Side by side
| Claude Sonnet 4.5 | GPT-5.3 Chat | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 44.0 | 42.1 |
| Released | 2025-09-29 | 2026-03-03 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 128K |
| Max output | 64K | 16K |
| Input $ / M tokens | $3 | $1.75 |
| Output $ / M tokens | $15 | $14 |
| Results tracked | 73 | 18 |
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Category by category
Coding Claude Sonnet 4.5 leads
Claude Sonnet 4.5: 47.8 (#54), GPT-5.3 Chat: 40.8 (#124)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Coding | 1489 | 1408 |
| SWE-bench Verified | 71.3% | — |
| SWE-bench Verified (bash only) | 71.4% | — |
| LMArena WebDev | 1393 | — |
| SWE-bench Multilingual | 67% | — |
| SciCode | 44.7% | — |
| GSO | 14.7% | — |
| WeirdML | 47.7% | — |
| ALE-Bench | 796.15 | — |
| AlgoTune | 1.52 | — |
Agentic & Tool Use Not comparable
Claude Sonnet 4.5: 38.1 (#30), GPT-5.3 Chat: —
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| Terminal-Bench | 46.5% | — |
| Berkeley Function Calling Leaderboard | 73.2% | — |
| GDPval | 42.5% | — |
| Remote Labor Index | 2.1% | — |
| τ²-bench Airline | 72% | — |
| τ²-bench Banking | 25.3% | — |
| τ²-bench Retail | 72.4% | — |
| τ²-bench Telecom | 84.9% | — |
| Cybench | 60% | — |
| DeepResearch Bench | 52.6% | — |
| OSWorld | 62.9% | — |
| LMArena Search | 1159 | — |
| METR Time Horizons | 67.4% | — |
| Vending-Bench 2 | 3,839 | — |
Reasoning Too close to call
Claude Sonnet 4.5: 26.9 (#113), GPT-5.3 Chat: 27.3 (#105)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Hard Prompts | 1462 | 1399 |
| ARC-AGI-2 | 13.6% | — |
| SimpleBench | 54.3% | — |
| Kagi LLM Benchmark | 57.9% | — |
| NYT Connections (extended) | 37.3% | — |
| ARC-AGI-1 | 63.7% | — |
| CritPt | 1.1% | — |
| Chess Puzzles | 12% | — |
| EnigmaEval | 6% | — |
| EBR-Bench | 2.4% | — |
| Mystery Game Puzzles | 17% | — |
| DTBench | 83.2% | — |
| LMCA | 38.8% | — |
| Epoch Capabilities Index | 146.84 | — |
| ForecastBench | 61.9 | — |
Math GPT-5.3 Chat leads
Claude Sonnet 4.5: 31.9 (#190), GPT-5.3 Chat: 35.4 (#146)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Math | 1448 | 1389 |
| FrontierMath (Tiers 1-3) | 23.9% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 77.8% | — |
| ProofBench | 19% | — |
| Omni-MATH | 55.3% | — |
| MATH Level 5 | 97.7% | — |
| FrontierMath (Feb 2025 set) | 15.2% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |
Knowledge Claude Sonnet 4.5 leads
Claude Sonnet 4.5: 48.4 (#70), GPT-5.3 Chat: 38.2 (#137)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Expert | 1483 | 1397 |
| GPQA Diamond | 82.3% | — |
| Humanity's Last Exam | 13.7% | — |
| SimpleQA Verified | 30.7% | — |
| MMLU-Pro | 86.9% | — |
| Vectara Hallucination Rate | 12% | — |
| GPQA (HELM) | 68.6% | — |
Multimodal Not comparable
Claude Sonnet 4.5: 34.1 (#84), GPT-5.3 Chat: —
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| VPCT | 39.8% | — |
| LMArena Document | 1450 | — |
Multilingual Claude Sonnet 4.5 leads
Claude Sonnet 4.5: 53.6 (#65), GPT-5.3 Chat: 50.5 (#119)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Non-English | 1425 | 1383 |
| LMArena Chinese | 1459 | 1433 |
| LMArena French | 1459 | 1398 |
| LMArena German | 1427 | 1384 |
| LMArena Japanese | 1390 | 1351 |
| LMArena Korean | 1403 | 1347 |
| LMArena Russian | 1436 | 1400 |
| LMArena Spanish | 1457 | 1371 |
Instruction Following Claude Sonnet 4.5 leads
Claude Sonnet 4.5: 75.2 (#74), GPT-5.3 Chat: 73.0 (#124)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Instruction Following | 1459 | 1378 |
| IFEval | 85% | — |
Long Context Claude Sonnet 4.5 leads
Claude Sonnet 4.5: 45.2 (#45), GPT-5.3 Chat: 42.6 (#115)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Longer Query | 1476 | 1396 |
Writing & Preference Claude Sonnet 4.5 leads
Claude Sonnet 4.5: 66.7 (#33), GPT-5.3 Chat: 63.3 (#65)
| Benchmark | Claude Sonnet 4.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Text | 1439 | 1389 |
| LMArena Creative Writing | 1442 | 1356 |
| EQ-Bench Creative Writing | 1678 | 1690 |
| LMArena Multi-Turn | 1465 | 1413 |
| WildBench | 85.4% | — |
Frequently asked questions
Is Claude Sonnet 4.5 better than GPT-5.3 Chat?
Claude Sonnet 4.5 is the stronger model overall, scoring 44.0 to 42.1 on the Noometry Index.
Which is cheaper, Claude Sonnet 4.5 or GPT-5.3 Chat?
GPT-5.3 Chat is cheaper. It lists at $1.75 per million input tokens and $14 per million output tokens; Claude Sonnet 4.5 lists at $3 and $15.
Is Claude Sonnet 4.5 or GPT-5.3 Chat better for coding?
Claude Sonnet 4.5 scores higher on coding benchmarks: 47.8 versus 40.8 in the Noometry coding category.
Which has the bigger context window?
Claude Sonnet 4.5 does, with 1M tokens against 128K.
How many benchmarks do Claude Sonnet 4.5 and GPT-5.3 Chat share?
18 benchmarks have published results for both models. Claude Sonnet 4.5 has 73 scored results on Noometry and GPT-5.3 Chat has 18.