Claude Sonnet 4.5 vs GPT-5.6 Terra
Side-by-side specs, pricing and capabilities. Both models run on Clade under one subscription, so you can switch between them in the same conversation.
Claude Sonnet 4.5 comes from Anthropic and GPT-5.6 Terra from OpenAI. The practical difference for most people is context, price, and which input types each one accepts.
GPT-5.6 Terra holds more in a single conversation — 1.1M tokens against 1M — which matters for long documents and large codebases.
GPT-5.6 Terra is the cheaper of the two on input tokens at $2.00 / 1M tokens.
| Specification | Claude Sonnet 4.5 | GPT-5.6 Terra |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Model ID | claude-sonnet-4-5-20250929 | gpt-5.6-terra |
| Context window | 1M | 1.1M |
| Max output | 64K | 128K |
| Input price | $3.00 / 1M tokens | $2.00 / 1M tokens |
| Output price | $15.00 / 1M tokens | $12.00 / 1M tokens |
| Knowledge cutoff | 2025-01 | — |
| Input types | text, image, file | image, text |
| Output types | text | image, text |
| Plan | Premium | Premium |
Which should you use?
Pick Claude Sonnet 4.5 when…
- You need file input, which the other model does not accept.
Pick GPT-5.6 Terra when…
- You need the larger context window — 1.1M against 1M.
- Cost matters: input runs at $2.00 / 1M tokens versus $3.00 / 1M tokens.
- You want longer single responses — up to 128K output tokens.
Related comparisons
Try both on Clade
You do not have to choose. One Clade subscription gives you Claude Sonnet 4.5, GPT-5.6 Terra, and every other model on the platform.