Claude Sonnet 4.5 vs GPT-5.5
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5.5 by OpenAI wins on 8 of 11 benchmarks against Claude Sonnet 4.5 by Anthropic, which leads on 3. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
General Intelligence: In general intelligence, GPT-5.5 scores 38.6 on AA Intelligence Index compared to Claude Sonnet 4.5's 21.2.
Coding: In coding, GPT-5.5 scores 74.9 on AA Coding Index compared to Claude Sonnet 4.5's 52.1, while GPT-5.5 scores 1272 on Design Arena ELO compared to Claude Sonnet 4.5's 1184, while GPT-5.5 scores 1269 on Website Arena ELO compared to Claude Sonnet 4.5's 1202.
Reasoning: In reasoning, GPT-5.5 scores 93.8% on GPQA Diamond compared to Claude Sonnet 4.5's 82.5%, while GPT-5.5 scores 37.3 on AA Agentic Index compared to Claude Sonnet 4.5's 17.5, while GPT-5.5 scores 75.3% on τ²-Bench Airline compared to Claude Sonnet 4.5's 73.0%.
Context: In context, GPT-5.5 scores 1.1M on Context Length compared to Claude Sonnet 4.5's 1.0M.
Pricing Comparison
Claude Sonnet 4.5 costs $3.0/1M input tokens and $15.0/1M output tokens, while GPT-5.5 costs $5.0/1M input and $30.0/1M output. Claude Sonnet 4.5 is the more affordable option for API usage.
Verdict
Claude Sonnet 4.5 leads across the board in affordability, making it the stronger overall choice in this comparison.
View Individual Model Pages
Claude Sonnet 4.5 vs GPT-5.5 — FAQ
Which is better, Claude Sonnet 4.5 or GPT-5.5?
GPT-5.5 wins on more benchmarks overall (8 vs 3). However, the best choice depends on your specific needs — each model excels in different areas.
How does Claude Sonnet 4.5 compare to GPT-5.5 for coding?
SWE-bench Verified data is not available for both models. Check the detailed comparison charts above for other coding-related metrics.
Is Claude Sonnet 4.5 cheaper than GPT-5.5?
Yes, Claude Sonnet 4.5 is cheaper. Claude Sonnet 4.5 costs $3.0/1M input and $15.0/1M output tokens. GPT-5.5 costs $5.0/1M input and $30.0/1M output tokens.
Which is faster, Claude Sonnet 4.5 or GPT-5.5?
Output speed data is not available for both models. Check the speed section of the comparison above for available performance data.
What benchmarks does the Claude Sonnet 4.5 vs GPT-5.5 comparison cover?
This comparison covers 11 benchmarks including GPQA Diamond, Input Cost, Output Cost, Context Length, AA Intelligence Index, AA Coding Index, AA Agentic Index, Cached Input Cost, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.