GPT-5.5 vs Claude 4.5 Sonnet

Compare GPT-5.5 and Claude 4.5 Sonnet. Build AI products powered by either model on Appaca.

Model Comparison

Feature	GPT-5.5	Claude 4.5 Sonnet
Provider	OpenAI	Anthropic
Model Type	text	text
Context Window	1,000,000 tokens	1,000,000 tokens
Input Cost	$5.00/ 1M tokens	$3.00/ 1M tokens
Output Cost	$30.00/ 1M tokens	$15.00/ 1M tokens

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Strengths & Best Use Cases

GPT-5.5

OpenAI

1. Strongest Agentic Coding Model

State-of-the-art on Terminal-Bench 2.0 (82.7%), Expert-SWE (73.1%), and SWE-Bench Pro (58.6%), outperforming GPT-5.4 on complex coding tasks.
Holds context across large systems, reasons through ambiguous failures, and carries changes through surrounding codebases with fewer tokens.

2. Higher Intelligence at GPT-5.4 Latency

Co-designed, trained, and served on NVIDIA GB200/GB300 NVL72 systems to match GPT-5.4 per-token latency while performing at a significantly higher level.
Uses fewer tokens to complete the same tasks, making it more efficient as well as more capable.

3. Powerful for Knowledge Work & Computer Use

Scores 84.9% on GDPval (44 occupations) and 78.7% on OSWorld-Verified for autonomous computer operation.
Excels at generating documents, spreadsheets, and reports; naturally moves across finding information, using tools, and checking output.

4. Scientific Research Co-Scientist

Leading performance on GeneBench, BixBench, and FrontierMath; helped discover a new proof about Ramsey numbers verified in Lean.
Strong enough to meaningfully accelerate progress at the frontiers of biomedical and mathematical research.

Claude 4.5 Sonnet

Anthropic

1. Best-in-class coding performance

#1 on SWE-bench Verified (77.2% standard, 82.0% high-compute).
Excels at debugging, architecture, and multi-file code generation.
Maintains coherence for extremely long tasks (30+ hours).

2. State-of-the-art computer use & agents

Leads OSWorld at 61.4%.
Strongest model for agentic workflows, multi-step tool use, and real computer control.
Powering Claude Code, the new Claude Agent SDK, and Chrome agent actions.

3. Advanced reasoning & math

Large improvements across reasoning-heavy benchmarks (AIME, MMMLU, τ2-bench, Terminal-Bench).
Deep multi-step reasoning with extended or interleaved thinking.

4. High alignment & safety

Most aligned Claude model to date with reduced deception, hallucinations, sycophancy, and harmful compliance.
Strong protections against prompt injection for agentic tasks (ASL-3 safeguards).

5. Domain-expert performance

Notable gains in finance, law, medicine, and STEM tasks.
Trusted by early customers for long-context legal analysis, multi-file engineering, security research, and red-teaming.