GPT-5.6 Terra: pricing, context and performance

GPT-5.6 Terra at a glance

GPT-5.6 Terra is a language model from OpenAI, released on July 9, 2026. That makes it 3 months old as of October 22, 2026. It is a closed model: you access it through an API, from OpenAI or one of the 46 providers listed on models.dev. It has a reasoning mode: it can "think" before answering, which helps with multi-step problems but uses more tokens, and therefore more money.

We file it under frontier models (24 models in this category on the site).

Benchmark results

According to results published by Epoch AI (checked on October 22, 2026), GPT-5.6 Terra has a capability index of 85.7 out of 100, computed on 5 benchmarks from our basket.

That puts it at #18 in our weekly model ranking.

• GPQA Diamond (PhD-level science questions): 93.3% — the best tracked model, Gemini 4 Argon, reaches 96.4%
• OTIS Mock AIME (competition mathematics problems): 99.7% — the best tracked model, GPT-5.5 Pro, reaches 100%
• FrontierMath (very hard research-level mathematics): 86% — the best tracked model, GPT-6 Astra, reaches 93.7%
• FrontierCode (advanced programming tasks): 41.3% — the best tracked model, Claude Opus 5.5, reaches 54.6%

What it can do

Its context window reaches 1,050,000 tokens, roughly 1,575 pages of text at 500 words per page: enough to load a whole book or a mid-sized codebase. A single answer can run to 128,000 tokens.

It accepts as input: text, image and PDF. Its knowledge stops at February 16, 2026: beyond that, it needs web search or your documents.

It can call tools (functions, APIs) and return structured JSON output, which makes it a possible foundation for an AI agent.

How much does GPT-5.6 Terra cost?

GPT-5.6 Terra costs $2 per million input tokens and $12 per million output tokens (developer's price, checked on October 22, 2026).

To put it in perspective: reading 20,000 tokens (about thirty pages) and writing 2,000 costs roughly $0.064; a thousand of those tasks, $64.

That is 1.2 times cheaper than the median output price of frontier models ($14.5).

Tokens read back from cache cost $0.20 per million, which helps an agent that keeps resending the same context.

To estimate your own budget, use the agent cost calculator.

When to choose it

Given its category, GPT-5.6 Terra is mainly aimed at hard tasks where quality matters more than cost: deep reasoning, complex code, long analyses.

Its very large context window makes it worth considering for analysing large sets of documents in a single request.

Before adopting it, test it on your own examples: benchmarks measure standard tasks, not your job.

Comparable models

In the same category, the models closest to GPT-5.6 Terra are:

• Gemini 3.7 Flash (Google DeepMind, index 85.9)
• Grok 4.6 (xAI, index 86.1)
• Qwen3.7 Max (Alibaba Cloud (Qwen), index 86.6)
• Gemini 3 Pro Preview (Google DeepMind, index 87)