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AI Models · Compare

GPT-5.5 vs Claude 4 Sonnet

Side-by-side intelligence, speed, price, benchmarks, strengths and weaknesses for GPT-5.5 and Claude 4 Sonnet — refreshed monthly.

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OpenAI

GPT-5.5

ProprietaryMar 2026

OpenAI’s 2026 flagship — strongest at reasoning, coding and tool use.

Open docs
Anthropic

Claude 4 Sonnet

ProprietaryFeb 2026

The Anthropic sweet spot — Opus-class coding at a fraction of the price.

Open docs

Head to head

Spec
GPT-5.5
Claude 4 Sonnet
Intelligence index↑ better
Winner82
75
Speed↑ better
95 tok/s
95 tok/s
Time to first token↓ better
Winner0.42 s
0.85 s
Context window↑ better
400k
Winner500k
Max output↑ better
16k
16k
Input price↓ better
$5.00 / 1M tokens
Winner$3.00 / 1M tokens
Output price↓ better
$15.00 / 1M tokens
$15.00 / 1M tokens
Blended price↓ better
$7.50 / 1M tokens
Winner$6.00 / 1M tokens
License
Proprietary
Proprietary
Input modalities
text, image
text, image
Output modalities
text
text

Benchmark showdown

MMLU
GPT-5.5
90.2
Claude 4 Sonnet
88.5
MMLU Pro
GPT-5.5
78.0
Claude 4 Sonnet
75.2
GPQA
GPT-5.5
62.5
Claude 4 Sonnet
58.0
MATH
GPT-5.5
89.1
Claude 4 Sonnet
82.0
HumanEval
GPT-5.5
93.0
Claude 4 Sonnet
93.2

Strengths, weaknesses and best-for

GPT-5.5
Strengths
  • Best-in-class reasoning
  • Huge 400k context
  • Strong tool use and agents
Weaknesses
  • Expensive vs Sonnet for non-reasoning tasks
  • Higher latency than gpt-5.5-mini
Best for
  • Agentic workflows
  • Complex coding
  • Hard math & research
Claude 4 Sonnet
Strengths
  • Best $/HumanEval ratio
  • Fast
  • 500k context
Weaknesses
  • Behind Opus on hardest reasoning
Best for
  • Production coding tools
  • Long-context RAG
  • Tool use

Quick verdict

  • Pick GPT-5.5 if you want it smarter.
  • Pick Claude 4 Sonnet if you want it cheaper and longer context.

Auto-generated from the spec sheet. Always validate on your own evals.

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