GPT-5.5

GPT-5.5 is OpenAI's flagship multimodal text model, released in April 2026 as the latest iteration in the GPT-5 generation of large language models. It processes text and images, supports long-horizon agentic workflows and tool use, and is distributed through the API, ChatGPT, and Microsoft Azure OpenAI Service. As of April 2026, it holds the top position on the Artificial Analysis Intelligence Index at 60.24, leading all publicly evaluated frontier models.

At a glance

• Lab: OpenAI
• Released: April 2026
• Modality: Text and multimodal (vision)
• Open weights: No (closed)
• Context window: Not officially disclosed; context length is consistent with GPT-5-generation capabilities
• Pricing: Available through tiered API pricing on the OpenAI platform; ChatGPT Free, Plus ($20/month), Pro ($200/month), Business, and Enterprise tiers
• Distribution channels: OpenAI API (https://platform.openai.com), ChatGPT (web and mobile), Microsoft Azure OpenAI Service

Origins

The GPT series traces its origins to GPT-1 (2018), OpenAI's first demonstration of large-scale pretraining on text corpora followed by fine-tuning for downstream tasks. GPT-2 (2019) and GPT-3 (2020) established the now-standard pattern of scaling transformer models on internet text, with GPT-3's 175 billion parameters setting the benchmark for the field at its time. GPT-4 (March 2023) added multimodal vision and significantly extended the model's capability on professional-level tasks; GPT-4o (May 2024) restructured the architecture for end-to-end multimodal processing rather than treating vision as an add-on.

The GPT-5 generation opened in mid-2025 with GPT-5, a model OpenAI described as representing a qualitative improvement over GPT-4o on reasoning, instruction following, and coding tasks. GPT-5.4 followed in February 2026. GPT-5.5 shipped six weeks later, in April 2026. That pace, roughly one major point release per quarter in the GPT-5 generation, reflects OpenAI's stated strategy of compressing its frontier release cadence.

The o-series reasoning models run alongside the GPT series rather than replacing it. o1 (September 2024) and o3 (early 2025) applied reinforcement learning to chain-of-thought reasoning, producing models that "think longer" on hard problems. GPT-5.5 integrates this technique directly: GPT-5.5 Pro, a variant available to Pro-tier ChatGPT subscribers, applies o-series reasoning RL to the base model. This means GPT-5.5 users can access both standard fast inference and extended-reasoning modes from a single model surface, rather than switching between the GPT and o-series lines.

Capabilities

GPT-5.5's core strength is text generation: question answering, summarization, instruction following, code generation, and extended multi-turn dialogue. On tasks that require synthesizing complex information across long contexts, the model performs well across the range of professional knowledge domains that standard benchmarks cover.

Vision is native rather than bolted on. GPT-5.5 processes images alongside text in the same context window, supporting chart interpretation, document understanding, screenshot analysis, and visual question answering. The vision capability is available through both the API and ChatGPT.

Tool use and agentic execution are first-class capabilities. GPT-5.5 supports function calling, structured outputs, and code execution through OpenAI's API. The Codex coding agent and the Operator computer-use agent, both integrated into the ChatGPT product surface, run on top of GPT-5.5 and demonstrate the model's ability to handle multi-step tasks with external tools and real-world interfaces.

The GPT-5.5 Pro variant adds extended reasoning via the o-series reinforcement learning pipeline. Where the standard model returns answers through direct inference, the Pro variant can spend additional compute on intermediate reasoning steps before producing an output, which is particularly effective on mathematical proofs, logic puzzles, and hard coding problems that benefit from step-by-step verification.

OpenAI has not published an architecture paper for GPT-5.5. No independently confirmed details on parameter count, training data, or mixture-of-experts configuration have been released as of April 2026.

Benchmarks and standing

As of April 2026, GPT-5.5 leads most major frontier benchmarks.

The Artificial Analysis Intelligence Index, which aggregates performance across a set of reasoning, language, and multimodal tasks into a composite score, places GPT-5.5 at 60.24. The next highest scores are Claude Opus 4.7 at 57.28, Gemini 3.1 Pro at 57.18, followed by DeepSeek V4 and Grok 4.20.

LMArena ELO scores based on head-to-head human preference judgments place GPT-5.5 at 1328 (general), 1456 (coding), and 1389 (vision). These are the highest scores across all three categories on the leaderboard as of April 2026.

On domain-specific benchmarks, GPT-5.5 leads on GPQA Diamond (94.2%), which tests graduate-level scientific reasoning, and on ARC-AGI Challenge (92.3), a test of novel problem-solving requiring adaptation beyond training patterns. On AIME 2025, the competitive mathematics benchmark, GPT-5.5 scores 96.7%.

The exception is SWE-bench Verified, the software engineering benchmark that tests real-world repository bug-fixing. Claude 4.5 Opus leads at 74.0; GPT-5.5 scores 68.5. HumanEval+, a function-completion coding benchmark, is dominated by GPT-5.5 on ELO but individual task performance across labs is closely bunched.

Frontier benchmark standings shift with each major model release. These positions are as of April 2026 and will change as labs ship updates.

Access and pricing

GPT-5.5 is available through several distribution channels.

The OpenAI API at https://platform.openai.com provides programmatic access. Developers can call GPT-5.5 for text and vision tasks, use function calling and structured outputs, and integrate code execution. OpenAI uses a tiered pricing model based on input and output tokens; specific per-token rates are published on the OpenAI pricing page at https://openai.com/api/pricing/.

ChatGPT is the consumer-facing product surface. The Free tier includes access to GPT-5.5 with usage limits. The Plus tier ($20/month) removes most limits and adds priority access. The Pro tier ($200/month) provides access to GPT-5.5 with extended-reasoning (the o-series reasoning RL variant), higher usage ceilings, and access to Codex and Operator in their current forms. Business and Enterprise tiers add team management, administrative controls, and expanded compliance features for organizational use.

Microsoft Azure OpenAI Service provides a managed deployment of GPT-5.5 within the Azure cloud. This channel is the primary route for enterprises that have existing Azure agreements or require data-residency and compliance configurations that the standard API does not support.

Comparison

Direct competitors to GPT-5.5 in the frontier text and multimodal category, as of April 2026:

• Claude Opus 4.7 (Anthropic). The closest competitor on overall benchmark score (57.28 on the Artificial Analysis Intelligence Index, vs. GPT-5.5's 60.24). Claude Opus 4.7 leads on SWE-bench Verified (74.0 to GPT-5.5's 68.5), which has made it the preferred model for enterprise software engineering workflows. Anthropic's commercial positioning emphasizes safety and enterprise reliability, which differentiates it in procurement processes where those attributes carry weight. On pricing, Anthropic's API rates are comparable to OpenAI's; neither has a clear cost advantage for standard inference.
• Gemini 3.1 Pro (Google DeepMind). The third-highest Intelligence Index score (57.18) and a model with the strategic advantage of deep integration with Google's existing product surface: Search, Workspace, and Android. Gemini 3.1 Pro's multimodal range extends to longer video contexts than GPT-5.5 currently supports. The primary risk to OpenAI from Gemini is not direct capability displacement but distribution: if Google routes enough queries through Gemini natively, it reduces the reach of ChatGPT and the OpenAI API for use cases that currently flow through Google products.
• Grok 4.20 (xAI). Real-time access to data through the X platform is a differentiator that GPT-5.5 lacks by default, making Grok more useful for tasks that depend on current events. On aggregate benchmarks, Grok 4.20 trails GPT-5.5 meaningfully. The distribution moat is X's user base, not raw capability.
• DeepSeek V4 (DeepSeek). The Chinese open-weights model that benchmarks well on the Intelligence Index while being available for self-hosted deployment at near-zero marginal cost. DeepSeek V4 does not close the capability gap with GPT-5.5 on the aggregate index, but it substantially changes the cost calculus for API-heavy use cases. Organizations that can run open-weights models at scale and are not constrained by data-sovereignty requirements have a plausible alternative at a fraction of OpenAI's per-token cost. This is the substitution risk OpenAI publicly names as a strategic concern.

Outlook

Open questions for the 12 to 18 months following GPT-5.5's release:

• GPT-6 timeline. OpenAI's release cadence for the GPT-5 generation has been roughly one major point release per quarter. The GPT-6 timeline has not been publicly disclosed. If the cadence holds, GPT-6 or an equivalent model would be expected in late 2026 or early 2027.
• Agentic capability expansion. Codex and Operator are early demonstrations of GPT-5.5's potential as the engine of multi-step autonomous workflows. The extent to which those products mature, gain real-world reliability, and convert into recurring enterprise revenue is the main product question over this period.
• Pricing pressure from open-weights labs. DeepSeek V4 and future open-weights releases from labs including Meta (Llama) and DeepSeek are available for self-hosted deployment. If open-weights capability continues to close the gap with closed frontier models, the API pricing that OpenAI depends on for revenue becomes harder to defend at current rates.
• o-series integration. GPT-5.5 Pro is the first model to integrate o-series reasoning directly into the standard GPT product line. Whether this architecture continues as a variant or becomes the default, and how OpenAI manages the compute cost of extended-reasoning inference at scale, will shape the product structure for GPT-6.
• Regulatory exposure. The EU AI Act's high-risk category classifications and the ongoing US federal debate on frontier AI oversight could add compliance requirements to GPT-5.5's enterprise use. How OpenAI navigates those requirements relative to Anthropic and Google, both of which have invested more publicly in safety and policy positioning, is a watchable signal.

Sources

• OpenAI: Introducing GPT-5.5. Official launch announcement, April 2026.
• TechCrunch: OpenAI releases GPT-5.5, bringing company one step closer to an AI 'super app'. Release context and product surface coverage.
• Artificial Analysis Intelligence Index. Frontier benchmark composite scores; GPT-5.5 at 60.24, April 2026 data.
• LMArena Leaderboard. Head-to-head ELO scores across general, coding, and vision categories.
• SWE-bench Verified leaderboard. Software engineering benchmark covering real repository bug-fixing tasks.
• OpenAI API pricing. Per-token pricing for GPT-5.5 and other OpenAI models.
• The Frontier Lab Exodus. Background on OpenAI alumni lab formation and the broader competitive landscape post-2024.