LLM·Dex
Newsletter
ProprietaryOpenAIflagshiptextvisionaudio

GPT-5.5

OpenAI's mid-cycle GPT-5 refresh, improved reasoning, tool use, and multimodal grounding over the 2025 launch.

Updated

Quick facts

Released
Mar 2026
Context
400K tokens
Output / 1M
Pricing not published
License
Proprietary

About GPT-5.5

GPT-5.5 is OpenAI's mid-2026 flagship and the model most production stacks are migrating to from GPT-5. The headline upgrades are richer agentic tool use, better long-context recall, and noticeably stronger vision grounding for screenshot- and chart-heavy workflows.

The model retains the unified GPT-5 architecture and the same Realtime/Responses API surface, so applications written against GPT-5 typically work against 5.5 with a model-name swap. OpenAI ships 5.5 as the default behind ChatGPT and the new Agent product.

For builders, the practical case for GPT-5.5 over GPT-5 is hard agent loops and any workload that benefits from longer reasoning at lower cost. For chat workloads where GPT-5 was already enough, the upgrade matters less.

Benchmarks

Published scores from OpenAI's model card or independent leaderboards. We do not publish numbers we cannot source, see methodology.

HumanEval
,
Python coding pass@1
MMLU
,
Broad academic knowledge
GPQA
,
Graduate-level reasoning
SWE-bench
,
Real software-engineering tasks
Benchmark scores not yet available. We only publish numbers we can source from official model cards or independent leaderboards, see methodology.

Capabilities

Strengths

  • Industry-leading tool-use and function-calling reliability
  • Strong end-to-end agent performance across SWE-bench and GAIA
  • Wide ecosystem support, ChatGPT, Realtime API, Responses API
  • Polished multimodal grounding on screenshots and charts

Tracked weaknesses

  • Pricing premium vs. open-weight alternatives
  • Output cost climbs fast on agent loops with many reasoning tokens
  • Stricter content policy than some peers for creative work

Pricing

Per-million-token rates as published by OpenAI.

Per-token pricing not yet published for GPT-5.5. Check the official provider site for current tiers.

Call GPT-5.5 from your code

Drop-in snippet for the OpenAI SDK. Set your API key in the environment and run.

typescript
import OpenAI from "openai";

const client = new OpenAI({
  // Use OPENAI_API_KEY for OpenAI, or your provider's key + baseURL.
  apiKey: process.env.OPENAI_API_KEY,
});

const completion = await client.chat.completions.create({
  model: "gpt-5-5",
  messages: [
    { role: "user", content: "What's the time complexity of quicksort?" },
  ],
});

console.log(completion.choices[0].message.content);

Best for

Tasks where GPT-5.5 ranks among LLMDex's top picks.

Compare GPT-5.5 with…

Frequently asked

  • How much does GPT-5.5 cost?
    OpenAI has not published per-token API pricing for GPT-5.5 at the time of writing. Check the official site for current pricing tiers, or compare against alternative models on LLMDex.
  • What is GPT-5.5's context window?
    GPT-5.5 supports a context window of 400K tokens.
  • Is GPT-5.5 open source?
    No. GPT-5.5 is a closed-weight model, you can use it via OpenAI's API but the model weights are not publicly downloadable.
  • When was GPT-5.5 released?
    GPT-5.5 was released on Mar 1, 2026 by OpenAI.
Friday digest

Intelligence, distilled weekly.

One short email every Friday, new model launches, leaderboard moves, and pricing drops. Curated by hand. Free, no spam.