Head to head
Claude Sonnet 5 vs GPT-5.6 Terra
Which is better, Claude Sonnet 5 or GPT-5.6 Terra?
Claude Sonnet 5 finishes ahead of GPT-5.6 Terra on the index, 87.9 to 84.4, and leads on all four scores: craft, speed, control and value. Both are scored on the same rubric, in the same week, and neither placing is sponsored.
Updated
Claude Sonnet 5
04 of 53
87.9
The coding workhorse: near the top on real software tasks, at a working price.
GPT-5.6 Terra
11 of 53
84.4
The middle of OpenAI's range, and the one most teams should actually deploy.
The four scores, side by side
| Score | Claude Sonnet 5 | GPT-5.6 Terra | Difference |
|---|---|---|---|
| Craft | 89 | 85 | +4 |
| Speed | 88 | 84 | +4 |
| Control | 89 | 88 | +1 |
| Value | 84 | 80 | +4 |
| Index score | 87.9 | 84.4 | +3.5 |
Which to pick
Claude Sonnet 5 is the safer pick on every axis we score. GPT-5.6 Terra earns its place in the index, but nothing in these four numbers argues for it over Claude Sonnet 5.
Claude Sonnet 5
Sonnet 5 is what most coding agents actually run on, and the benchmark gap to the tier above it is smaller than the price gap. It applies patches that compile, follows a repository's existing conventions, and holds up over the long tool-calling chains that agent frameworks generate. Anthropic has been discounting it, so check the current rate before you build a budget on it.
Where it shines
- Among the strongest models on verified software engineering tasks
- Priced to run continuously rather than occasionally
- Reliable tool calling over long chains, which is what breaks weaker models
GPT-5.6 Terra
Terra keeps the million-token context and most of Sol's competence, then costs a fraction of it. It is the balanced member of the family: quick enough for product work, strong enough for the reasoning most applications actually contain, and backed by the deepest tooling ecosystem of any model in this index. Nothing about it is remarkable, which is the compliment.
Where it shines
- Best-supported model in the industry: every framework ships an adapter
- Million-token context at a mid-tier price
- Predictable structured output, which matters more than benchmarks in production