Question 1

How much does GPT-5.5 cost?

Accepted Answer

GPT-5.5 costs $5 per 1M input tokens and $30 per 1M output tokens via the API, double GPT-5.4's $2.50/$15. GPT-5.5 Pro is far pricier at $30/$180. Batch and Flex modes run at half rate. In ChatGPT, GPT-5.5 Thinking is on Plus and above, and GPT-5.5 Instant is the free default.

Question 2

Is GPT-5.5 better than Claude Opus 4.7?

Accepted Answer

It depends on the task. GPT-5.5 wins on agentic and shell-driven work like Terminal-Bench 2.0. Opus 4.7 leads on 6 of 10 shared benchmarks, hallucinates far less (36% vs 86% on AA-Omniscience), and costs $5 less per million output tokens. For deep reasoning and factual accuracy, Opus is the safer pick.

Question 3

Is GPT-5.5 still the leading AI model?

Accepted Answer

No, not anymore. GPT-5.5 topped the Artificial Analysis Intelligence Index at 60 when it launched on April 23, 2026, but Claude Opus 4.8 (May 28) has since overtaken it (56 vs 55). Claude Fable 5 briefly led in early June, but Anthropic suspended it for all customers on June 12 after a US export-control directive, so it is not currently available. GPT-5.5 remains OpenAI's current flagship, with no GPT-5.6 officially announced as of June 2026.

Question 4

What is GPT-5.5 Instant?

Accepted Answer

GPT-5.5 Instant is the fast default model that replaced GPT-5.3 Instant in ChatGPT on May 5, 2026. It auto-routes between a light model and GPT-5.5 Thinking per prompt, gives shorter answers, and (per OpenAI's internal evals) cuts hallucinations 52.5% on high-stakes prompts versus GPT-5.3 Instant.

Question 5

Does GPT-5.5 hallucinate a lot?

Accepted Answer

On the AA-Omniscience benchmark, yes: GPT-5.5 (xhigh) records an 86% hallucination rate, far above Opus 4.7 (36%) and Gemini 3.1 Pro (50%). It's more likely to fabricate an answer than admit it doesn't know. Verify anything factual it gives you, especially in high-stakes domains.