GPT-5.5 Pro vs GPT-5.6 Terra
GPT-5.5 Pro and GPT-5.6 Terra are both current openai production-tier models. GPT-5.6 Terra is meaningfully cheaper at $2.5 / $15 per 1M. GPT-5.6 Terra has a 1.1M context window — about 3× the 400k of GPT-5.5 Pro. GPT-5.5 Pro leads on reasoning.
Specs side by side
| Metric | OpenAI GPT-5.5 Pro | OpenAI GPT-5.6 Terra |
|---|---|---|
| Input price (per 1M) | $30 | $2.5 |
| Output price (per 1M) | $180 | $15 |
| Context window | 400k tokens | 1.1M tokens |
| Speed tier | slow | balanced |
| Open weights | No | No |
| EU region | No | Yes |
| Free tier | No | No |
| Prompt caching | Yes | Yes |
| Vision input | Yes | Yes |
| Extended thinking | Yes | Yes |
When to choose each
Choose GPT-5.5 Pro if…
- Reasoning is central to your workload
Choose GPT-5.6 Terra if…
- Cost is a priority ($2.5 / $15 per 1M vs $30 / $180 per 1M)
- You need 1.1M context (3× more than GPT-5.5 Pro)
- EU data residency is required
Benchmark delta
GPT-5.5 Pro leads on
- Reasoning
GPT-5.6 Terra leads on
GPT-5.6 Terra has no meaningful benchmark lead in this pair.
FAQ — GPT-5.5 Pro vs GPT-5.6 Terra
GPT-5.5 Pro vs GPT-5.6 Terra — which is better?
GPT-5.5 Pro and GPT-5.6 Terra are both current openai production-tier models. GPT-5.6 Terra is meaningfully cheaper at $2.5 / $15 per 1M. GPT-5.6 Terra has a 1.1M context window — about 3× the 400k of GPT-5.5 Pro. GPT-5.5 Pro leads on reasoning. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does GPT-5.5 Pro pricing compare to GPT-5.6 Terra?
GPT-5.5 Pro costs $30 / $180 per 1M vs GPT-5.6 Terra at $2.5 / $15 per 1M. GPT-5.6 Terra is cheaper on output tokens by roughly 1100%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does GPT-5.5 Pro or GPT-5.6 Terra have the bigger context window?
GPT-5.6 Terra has a 1.1M-token context window — 3× the 400k context of GPT-5.5 Pro. Enough for entire codebases, books, or multi-document RAG.
Is there a free tier for GPT-5.5 Pro or GPT-5.6 Terra?
GPT-5.5 Pro: no — Paid-only — no free tier. GPT-5.6 Terra: no — Free $5 credit for new accounts; paid thereafter.
Which is better for coding — GPT-5.5 Pro or GPT-5.6 Terra?
GPT-5.5 Pro leads on coding benchmarks (GPT-5.5 Pro: 96/100, GPT-5.6 Terra: 93/100). For production coding agents also weigh tool-use performance — GPT-5.5 Pro scores 94, GPT-5.6 Terra scores 93.