GPT-5.6 Terra
by OpenAI · openai/gpt-5.6-terra · #357 cheapest of 422 paid models
Prices updated Sep 20, 2026, 12:34 AM UTC · refreshed hourly
GPT-5.6 Terra is a balanced model in OpenAI's GPT-5.6 series, positioned between the flagship Sol tier and the cost-efficient Luna tier. It is suited for everyday coding, reasoning, and agentic...
Compare vs:Claude Sonnet 5Claude Opus 4.6Claude Haiku 4.5Gemini 3.6 Flash
Pricing
Input
$2.00
per 1M tokens
Output
$12.00
per 1M tokens
Blended (3:1)
$4.50
3 input : 1 output
Cache read
$0.20
per 1M cached tokens
Cache write
$2.50
per 1M tokens
Cache & batch economics
Effective prices for GPT-5.6 Terra with prompt caching.
| Cache hit rate | Effective blended $/1M | Example request* | vs no cache |
|---|---|---|---|
| 0% | $4.50 | $0.216 | — |
| 50% | $3.83 | $0.126 | −42% |
| 90% | $3.29 | $0.054 | −75% |
*Example: 100K sticky context + 2K new input + 1K output. Batch discount is an approximate 50% off list rates for this provider’s batch API. Confirm on the vendor’s pricing page.
What a request costs
| Workload | Input tokens | Output tokens | Cost / request | Cost / 1K requests |
|---|---|---|---|---|
| Short chat message | 500 | 300 | $0.0046 | $4.60 |
| Document summary | 8,000 | 1,000 | $0.028 | $28.00 |
| Codebase question (RAG) | 30,000 | 2,000 | $0.084 | $84.00 |
| Long-context analysis | 150,000 | 5,000 | $0.36 | $360.00 |
Performance
Intelligence Index
42.1
AA composite quality
Coding Index
76.7
Math Index
—
Agentic Index
43.7
Output speed
88 tok/s
median
Time to first token
130.06s
median
Time to first answer
130.06s
after reasoning tokens
Artificial Analysis benchmarks
| Benchmark | Score |
|---|---|
| GPQA Diamond | 92.5% |
| Humanity's Last Exam | 42.9% |
| SciCode | 55.0% |
| IFBench | 71.2% |
| AA-LCR (Long Context Reasoning) | 83.0% |
| Terminal-Bench Hard | 57.6% |
| Terminal-Bench 2.1 | 88.0% |
| τ²-Bench (Telecom) | 86.3% |
| τ³-Bench Banking | 40.2% |
Specs
Context window
1.05M
tokens
Max output
128K
tokens
Input modalities
file, image, text
Tokenizer
GPT