OpenAI's flagship model GPT-5.6 Sol with a 1.05M-token context window, 128K max output, and strong browsing and terminal capabilities.
Anthropic's flagship model Claude Opus 5 with a 1M-token context window, self-verification, and the highest benchmark scores on reasoning and agentic tasks.
GPT-5.6 Sol closes the reasoning gap with Claude Opus 5, but Claude's lower hallucination rate and stronger benchmark scores on 9 of 12 tests still matter more for professional work that requires accuracy over speed.
GPT-5.6 Sol and Claude Opus 5 are the flagship models from OpenAI and Anthropic in 2026. Both were tested on output quality, workflow integration, context handling, onboarding cost, and failure signaling across five dimensions scored 1 to 5. Verdict as of August 2026.
Pick in 10 seconds
- ✓You need faster output speed (64 tokens/sec vs 56 tokens/sec)
- ✓Your workflow depends on ChatGPT's ecosystem of GPTs and integrations
- ✓You want a slightly larger context window (1.05M vs 1M tokens)
- ✓Accuracy matters more than speed in your work
- ✓You need the lowest hallucination rate available
- ✓You work on agentic tasks, code, or novel reasoning problems
Round by round
Output reliability
ClaudeClaude Opus 5 leads on 9 of 12 benchmarks, including a 14.6-point gap on SWE-bench Pro.
- →Opus 5 outperforms Sol on ARC-AGI-3 by 3.9x and on SWE-bench Pro by 14.6 points
- →Sol wins on DeepSWE 1.1 and HealthBench Professional, but loses the other 10
Workflow fit
GPT-5GPT-5.6 Sol benefits from ChatGPT's broader ecosystem: voice, images, custom GPTs, and desktop apps.
- →ChatGPT's platform offers desktop, mobile, voice mode, image generation, and browsing
- →Claude's platform is narrower but deeper for document and code workflows via Projects and Claude Code
Context handling
TieNear parity: Sol accepts 1.05M tokens, Opus 5 accepts 1M. Both handle long context well.
- →GPT-5.6 Sol's 1.05M-token window is 5% larger than Opus 5's 1M
- →Both retain detail at the far end of long documents in practice
Learning curve vs. payoff
TieA tie at the same price point. Both models are accessible through 20-dollar subscriptions.
- →ChatGPT Plus at 20 dollars/month gives access to GPT-5.6 Sol
- →Claude Pro at 20 dollars/month gives access to Opus 5 with extended thinking
Failure transparency
ClaudeClaude refuses more explicitly when uncertain. GPT-5.6 Sol pads uncertain answers with confident prose.
- →Claude declined a speculative medical question with a visible refusal
- →Sol answered the same question with hedged language buried in otherwise confident text
Questions people actually ask
Is GPT-5 or Claude Opus 5 better for coding tasks?
Claude Opus 5 is better for coding. It leads GPT-5.6 Sol by 14.6 points on SWE-bench Pro and handles full-file refactors with fewer hallucinated imports. Sol is faster at generating code (64 tokens per second vs 56), but speed matters less when the output needs more corrections. For production-quality code, Claude wins.
How do GPT-5 Sol and Claude compare on reasoning benchmarks?
Claude Opus 5 leads on 9 of 12 major benchmarks, including ARC-AGI-3 (3.9x better) and FrontierCode 1.1. GPT-5.6 Sol wins on DeepSWE 1.1 and HealthBench Professional. The overall gap is narrow on some tests but wide on novel reasoning and agentic tasks, where Opus 5 pulls ahead consistently.
Which model hallucinates less, GPT-5 or Claude?
Claude Opus 5 hallucinates less in both coding and factual tasks. Its self-verification feature catches errors before they reach the output. GPT-5.6 Sol has improved since earlier versions, but it still produces confident-sounding statements on uncertain facts more often. For work that requires trust without re-checking, Claude is the safer choice.
Is GPT-5 worth the price difference over Claude Pro?
The subscription price is identical: both ChatGPT Plus and Claude Pro cost 20 dollars per month. On the API, Sol costs 5 dollars input and 30 dollars output per million tokens, while Opus 5 costs 5 dollars input and 25 dollars output. Claude is 17% cheaper on output tokens. The price favors Claude unless you need ChatGPT's ecosystem.