GPT-5.5 Pro
openai/gpt-5.5-pro-20260423
OpenAI: GPT-5.5 Pro accepts file, image, and text inputs and provides text outputs. It has a context length of 1,050,000 tokens and supports tools and reasoning. Input pricing is $30 per million tokens, while output pricing is $180 per million tokens.
- tool use
- structured outputs
- reasoning
At a glance
Specifications
What the API gives you
- Context window
- 1.1M tokens
- Max output
- 128K tokens
- Input price
- $30 / 1M tokens
- Output price
- $180 / 1M tokens
- Cache read
- —
- Modalities
- file, image, text → text
- Knowledge cutoff
- Dec 1, 2025
- Released
- Apr 8, 2026
Measured evidence
Public benchmark record
- FrontierMath Tiers 1-3 (Epoch AI)‡
- 87.7% ± 1.92026-06-12xhigh effort, evaluated 2026-06-12
LMArena data licensed CC-BY-4.0. Aider (Apache-2.0) and SWE-bench (MIT) are open. Design Arena uses blind human preference. ‡ Submitted scaffold plus model result. Compare the harness and effort settings, not only the model name.
Task evidence
How broad is the support?
Each status is exact to this model version and the selected task. Official release claims remain provisional.
- Best LLM for Competition MathProvisional evidence
19% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from OTIS Mock AIME (Epoch AI) or LiveBench Mathematics. 6 of 6 configured evaluation feeds currently have results.
- Best LLM for Math & ReasoningProvisional evidence
8% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from GPQA Diamond (Epoch AI) or OTIS Mock AIME (Epoch AI). 7 of 7 configured evaluation feeds currently have results.
Recommendation coverage
Where this model appears
Not currently included in a published recommendation. The task evidence panel above says exactly what is confirmed and what is still missing.
Catalog data via OpenRouter and models.dev. Last checked within the past 6 hours.