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Claude Opus 4.8 vs GPT-5.5

How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Claude Opus 4.8 and GPT-5.5.

Anthropic

Claude Opus 4.8

Claude Opus 4.8 is Anthropic's most capable generally available model in the Opus family. It supports text, image, and file inputs with text output, with reasoning support and a 1M-token...

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OpenAI

GPT-5.5

GPT-5.5 is OpenAI’s frontier model designed for complex professional workloads, building on GPT-5.4 with stronger reasoning, higher reliability, and improved token efficiency on hard tasks. It features a 1M+ token...

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Technical Specifications

SpecificationClaude Opus 4.8GPT-5.5
ProviderAnthropicOpenAI
Context Window1,000,000 tokens1,050,000 tokens
Agent Suitability97/10095/100
Time to First Token (TTFT)520 ms380 ms
Deployment Modelmanaged apimanaged api
Production Stabilitybetastable
API AvailableYesYes
Released Date2026-05-272026-04-24

API Pricing Comparison

Input Price per Million Tokens

Claude Opus 4.8

$5.00

GPT-5.5

$5.00

Output Price per Million Tokens

Claude Opus 4.8

$25.00

GPT-5.5

$30.00

Want to test both models live?

Run side-by-side prompt prompts in our dynamic Sandbox. Check execution speeds, latency metrics, and compute actual costs in real-time.

Benchmark Performance Metrics

Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.

MMLUGeneral knowledge & multi-task understanding
9540.0%vs9420.0%
Claude Opus 4.8
GPT-5.5
HumanEvalPython coding & logic synthesis
9720.0%vs9680.0%
Claude Opus 4.8
GPT-5.5
MATHComplex mathematical problem solving
9410.0%vs9350.0%
Claude Opus 4.8
GPT-5.5
GPQAGraduate-level expert reasoning
8650.0%vs8420.0%
Claude Opus 4.8
GPT-5.5
HellaSwagCommonsense reasoning and inference
9920.0%vs9900.0%
Claude Opus 4.8
GPT-5.5
MT-BenchMulti-turn conversation flow quality
980.0%vs970.0%
Claude Opus 4.8
GPT-5.5

Claude Opus 4.8 Quirks & Gotchas

  • Best-in-class for autonomous code repair and multi-agent orchestration
  • Preview model — API may introduce breaking changes without notice

GPT-5.5 Quirks & Gotchas

  • Best for JSON schema adherence — strict mode available via response_format parameter
  • Requires explicit tool_choice for deterministic function calling