High-volume, cost-sensitive work
Choose GPT-5.6 Terra
GPT-5.6 Terra costs 25% less on a typical mix of three input tokens for every output token ($4.50 against $6.00 per million tokens).
Claude Sonnet 4.5 vs GPT-5.6 Terra: price, context and capabilities
Choose GPT-5.6 Terra for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), very long inputs and the latest release; on the other points the two are level or the data is missing.
In short
- GPT-5.6 Terra is 25% cheaper than Claude Sonnet 4.5 at the headline price ($4.50 / 1M tokens vs $6.00 / 1M tokens).
- GPT-5.6 Terra reads more per request: 1.05M tokens against 200k.
- GPT-5.6 Terra is the newer model (Jul 9, 2026, against September 2025).
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 $15.00 for Claude Sonnet 4.5. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose GPT-5.6 Terra
GPT-5.6 Terra charges $0.20 per million cached input tokens, against $0.30 for Claude Sonnet 4.5.
Very long inputs
Choose GPT-5.6 Terra
GPT-5.6 Terra reads up to 1.05M tokens per request, against 200k for Claude Sonnet 4.5.
Latest release
Choose GPT-5.6 Terra
GPT-5.6 Terra is the newer release (Jul 9, 2026, against September 2025 for Claude Sonnet 4.5).
Monthly cost at three volumes
| Volume | Claude Sonnet 4.5 | GPT-5.6 Terra | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $6.75 | $5.00 | GPT-5.6 Terra, $1.75 less |
| Production: 20M input, 5M output tokens | $135.00 | $100.00 | GPT-5.6 Terra, $35.00 less |
| Scale: 500M input, 100M output tokens | $3,000 | $2,200 | GPT-5.6 Terra, $800.00 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Sonnet 4.5 | GPT-5.6 Terra | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Deprecated | Generally available |
| Headline price | $6.00 / 1M tokens | $4.50 / 1M tokens |
| Input | $3.00 / 1M tokens | $2.00 / 1M tokens |
| Output | $15.00 / 1M tokens | $12.00 / 1M tokens |
| Cached input | $0.30 / 1M tokens | $0.20 / 1M tokens |
| Context window | 200k | 1.05M |
| Max output | 64k | 128k |
| Released | September 2025 | Jul 9, 2026 |
| Knowledge cutoff | No data | 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-sonnet-4-5-20250929 | gpt-5.6-terra |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Sonnet 4.5 | GPT-5.6 Terra |
|---|---|---|
| Intelligence Index | No data | 42.1 |
| Terminal-Bench Hard | No data | 57.6% |
| SciCode | No data | 55% |
| GPQA Diamond | No data | 92.5% |
| Humanity's Last Exam | No data | 42.9% |
| IFBench (instruction following) | No data | 71.2% |
| τ²-Bench (agentic tool use) | No data | 86.3% |
| MMMU-Pro (visual reasoning) | No data | 80.7% |
| Long-context reasoning (AA-LCR) | No data | 83% |
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 Sonnet 4.5 or GPT-5.6 Terra?
Choose GPT-5.6 Terra for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), very long inputs and the latest release; on the other points the two are level or the data is missing.
Which is cheaper, Claude Sonnet 4.5 or GPT-5.6 Terra?
GPT-5.6 Terra is 25% cheaper than Claude Sonnet 4.5 at the headline price ($4.50 / 1M tokens vs $6.00 / 1M tokens).
Which has the larger context window, Claude Sonnet 4.5 or GPT-5.6 Terra?
GPT-5.6 Terra reads more per request: 1.05M tokens against 200k.
What is the difference between Claude Sonnet 4.5 and GPT-5.6 Terra?
Claude Sonnet 4.5 is made by Anthropic and GPT-5.6 Terra by OpenAI. GPT-5.6 Terra is 25% cheaper than Claude Sonnet 4.5 at the headline price ($4.50 / 1M tokens vs $6.00 / 1M tokens). GPT-5.6 Terra reads more per request: 1.05M tokens against 200k. GPT-5.6 Terra is the newer model (Jul 9, 2026, against September 2025).
How much do Claude Sonnet 4.5 and GPT-5.6 Terra cost per month?
At 20 million input and 5 million output tokens a month, Claude Sonnet 4.5 costs $135.00 and GPT-5.6 Terra costs $100.00, at standard rates.
Which is newer, Claude Sonnet 4.5 or GPT-5.6 Terra?
GPT-5.6 Terra was released on Jul 9, 2026 and Claude Sonnet 4.5 on September 2025.