ChatGPT Flagship Verified 19 Aug 2026

GPT-5.5 Pro

The previous high-effort tier for the most demanding tasks.

Previous generation. Use GPT-5.6 Sol instead. Previous generation. GPT-5.6 shipped 9 Jul 2026.

Maker: OpenAI
Context: Large (see OpenAI docs)
Pricing: See OpenAI pricing / See OpenAI pricing

Available on Pro, Business, and Enterprise plans.

Best for

The hardest reasoning and analysis you'd throw at ChatGPT
Long, complex documents and codebases
When you'd rather wait and get it right

Prompting quirks

Reserve it for when the answer actually matters

Pro is slower and pricier. Use it for the 10% of tasks where depth beats speed; default everything else down a tier.

Give it everything relevant up front

It rewards rich context. Paste the full brief, the constraints, and the prior attempts rather than feeding it piecemeal.

Copy-paste example

Tuned for GPT-5.5 Pro. Swap in your own content where marked.

Strategy stress-test

Here is our full product strategy and the market context:
{paste strategy + context}
Act as a skeptical board member. Where is this strategy most likely to
fail in the next 12 months? Give me the three scenarios that would kill
it and the leading indicator for each.

Facts verified against the official OpenAI docs on 19 August 2026.