GPT-5.6 Terra

openaiopenai/gpt-5.6-terra

OpenAI's GPT-5.6 family (Terra tier). Frontier reasoning and coding at the GPT-5.5 price/quality tier.

GPT-5.6 Terra is the mid tier of OpenAI's GPT-5.6 family, verified live 2026-07-27 across three surfaces: the OpenAI direct API, Azure OpenAI eastus2 (deployed by the operator the same day), and OpenRouter. It sits at the same cost tier as GPT-5.4 with a newer checkpoint.

Best for

• General-purpose reasoning and coding workloads that currently run on GPT-5.4/5.5

Reach for something else if

• Cost-sensitive high-volume simple tasks — route to gpt-5.6-luna instead

Context Length

Max Output

128K

Input Priceper 1M tokens

$2.16/ 1M tokens

Output Priceper 1M tokens

$12.96/ 1M tokens

Modalities

textimage→text

Capabilities

Vision

Pricing Breakdown

Type	Rate
Prompts up to 272K tokens
Input	$2.16 / 1M tokens
Output	$12.96 / 1M tokens
Cached input	$0.216 / 1M tokens
Cache write (5m)	$2.70 / 1M tokens
Prompts over 272K tokens
Input	$4.32 / 1M tokens
Output	$19.44 / 1M tokens
Cached input	$0.432 / 1M tokens
Cache write	$5.40 / 1M tokens

Tiered pricing: when a request's prompt (input, cached tokens included) is over 272K tokens, every token in that request is billed at the long-context rates; exactly 272K is still the base rate.

Supported Parameters

temperaturemax_tokenstop_ptoolstool_choiceresponse_formatreasoningstop

Specifications

Release date	Not publicly disclosed	unknown
License	Commercial via OpenAI API / Azure OpenAI	verified

Benchmarks

Benchmark	Distribution	Score	Source
Not publicly disclosed	—	Not publicly disclosed	—

API Usage Examples

Use the global api.therouter.ai endpoint shown below for new integrations; the legacy China accelerated endpoint is retired.

cURL

curl https://api.therouter.ai/v1/chat/completions   -H "Content-Type: application/json"   -H "Authorization: Bearer $THE_ROUTER_API_KEY"   -d '{
    "model": "openai/gpt-5.6-terra",
    "messages": [
      {"role": "user", "content": "Summarize the key points from this input."}
    ]
  }'

API guide

Chat completion

cURL

curl https://api.therouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $THEROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"openai/gpt-5.6-terra","messages":[{"role":"user","content":"Hello"}]}'

More from openai

openai/gpt-5.6-solHigher tier in the same family openai/gpt-5.6-lunaCost-efficient sibling

Fact ledger — every claim on this page traces here

source	URL	retrieved
Release date	—	—	unknown
License	—	—	verified
Not publicly disclosed	openai.com ↗	2026-07-27	unknown