High-volume, cost-sensitive work
Choose GPT-5.6 Terra
GPT-5.6 Terra costs 44% less on a typical mix of three input tokens for every output token ($4.50 against $8.00 per million tokens).
Claude Opus 5.5 vs GPT-5.6 Terra: price, context and capabilities
Choose Claude Opus 5.5 for the hardest reasoning tasks, the latest release and the most recent knowledge. Choose GPT-5.6 Terra for high-volume, cost-sensitive work and writing and code generation.
In short
- GPT-5.6 Terra is 44% cheaper than Claude Opus 5.5 at the headline price ($4.50 / 1M tokens vs $8.00 / 1M tokens).
- GPT-5.6 Terra reads more per request: 1.05M tokens against 1M.
- Claude Opus 5.5 is the newer model (September 2026, against Jul 9, 2026).
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose GPT-5.6 Terra
GPT-5.6 Terra charges $12.00 per million output tokens, against $20.00 for Claude Opus 5.5. Output dominates the bill when answers are long.
Hardest reasoning tasks
Choose Claude Opus 5.5
Claude Opus 5.5 scores 57.6 on the Artificial Analysis Intelligence Index, against 42.1 for GPT-5.6 Terra.
Reasoning over long documents
Either one
They are practically level on Long-context reasoning (AA-LCR) (84.7% and 83%).
Latest release
Choose Claude Opus 5.5
Claude Opus 5.5 is the newer release (September 2026, against Jul 9, 2026 for GPT-5.6 Terra).
Most recent knowledge
Choose Claude Opus 5.5
Claude Opus 5.5 was trained on data up to June 2026, against February 2026 for GPT-5.6 Terra.
Monthly cost at three volumes
| Volume | Claude Opus 5.5 | GPT-5.6 Terra | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $9.00 | $5.00 | GPT-5.6 Terra, $4.00 less |
| Production: 20M input, 5M output tokens | $180.00 | $100.00 | GPT-5.6 Terra, $80.00 less |
| Scale: 500M input, 100M output tokens | $4,000 | $2,200 | GPT-5.6 Terra, $1,800 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Opus 5.5 | GPT-5.6 Terra | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Generally available | Generally available |
| Headline price | $8.00 / 1M tokens | $4.50 / 1M tokens |
| Input | $4.00 / 1M tokens | $2.00 / 1M tokens |
| Output | $20.00 / 1M tokens | $12.00 / 1M tokens |
| Cached input | $0.20 / 1M tokens | $0.20 / 1M tokens |
| Context window | 1M | 1.05M |
| Max output | 128k | 128k |
| Released | September 2026 | Jul 9, 2026 |
| Knowledge cutoff | June 2026 | February 2026 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | claude-opus-5-5 | gpt-5.6-terra |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Opus 5.5 | GPT-5.6 Terra |
|---|---|---|
| Intelligence Index | 57.6 | 42.1 |
| SciCode | 66.9% | 55% |
| Humanity's Last Exam | 61.4% | 42.9% |
| MMMU-Pro (visual reasoning) | 87.7% | 80.7% |
| Long-context reasoning (AA-LCR) | 84.7% | 83% |
| Terminal-Bench Hard | No data | 57.6% |
| GPQA Diamond | No data | 92.5% |
| IFBench (instruction following) | No data | 71.2% |
| τ²-Bench (agentic tool use) | No data | 86.3% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Claude Opus 5.5 or GPT-5.6 Terra?
Choose Claude Opus 5.5 for the hardest reasoning tasks, the latest release and the most recent knowledge. Choose GPT-5.6 Terra for high-volume, cost-sensitive work and writing and code generation.
Which is cheaper, Claude Opus 5.5 or GPT-5.6 Terra?
GPT-5.6 Terra is 44% cheaper than Claude Opus 5.5 at the headline price ($4.50 / 1M tokens vs $8.00 / 1M tokens).
Which has the larger context window, Claude Opus 5.5 or GPT-5.6 Terra?
GPT-5.6 Terra reads more per request: 1.05M tokens against 1M.
What is the difference between Claude Opus 5.5 and GPT-5.6 Terra?
Claude Opus 5.5 is made by Anthropic and GPT-5.6 Terra by OpenAI. GPT-5.6 Terra is 44% cheaper than Claude Opus 5.5 at the headline price ($4.50 / 1M tokens vs $8.00 / 1M tokens). GPT-5.6 Terra reads more per request: 1.05M tokens against 1M. Claude Opus 5.5 is the newer model (September 2026, against Jul 9, 2026).
How much do Claude Opus 5.5 and GPT-5.6 Terra cost per month?
At 20 million input and 5 million output tokens a month, Claude Opus 5.5 costs $180.00 and GPT-5.6 Terra costs $100.00, at standard rates.
Which is newer, Claude Opus 5.5 or GPT-5.6 Terra?
Claude Opus 5.5 was released on September 2026 and GPT-5.6 Terra on Jul 9, 2026.