OpenAI
GPT-5.1 Chat
Chat-tuned GPT-5.1 for polished assistants, writing, and product conversations
- Context
- 128K
- Max output
- 16.4K
- Input / 1M
- $1.25
- Output / 1M
- $10.00
- Output speed
- —
Accepts
- Text input
- Image input
Produces
- Text output
AI model comparison
Compare recorded price, context, output limits, speed, latency, capabilities, and input/output support. Every missing value stays visible, and unsourced benchmarks are excluded.
GPT-5.1 Chat and GPT-5.6 Terra both come up when teams are choosing a model for production work, and the honest answer usually depends on your workload rather than a leaderboard. This page puts their published specifications side by side — context window, token pricing, supported inputs and outputs — so you can see where they actually differ.
OpenAI
Chat-tuned GPT-5.1 for polished assistants, writing, and product conversations
Accepts
Produces
OpenAI
OpenAI's mid-tier GPT-5.6 reasoning model with a 1.05M token context window, function calling, and vision, priced between GPT-5.5 and GPT-5.5 Pro.
Accepts
Produces
At a glance
This is a directional summary of the values recorded in this directory—not a universal quality verdict. Test the finalists on your own prompts before committing.
Where GPT-5.1 Chat leads in recorded data
Where GPT-5.6 Terra leads in recorded data
Context capacity
Higher listed limit
GPT-5.1 Chat:128K
GPT-5.6 Terra:1.1M
GPT-5.6 Terra
Maximum output
Higher listed limit
GPT-5.1 Chat:16.4K
GPT-5.6 Terra:128K
GPT-5.6 Terra
Input price
Lower recorded price
GPT-5.1 Chat:$1.25
GPT-5.6 Terra:$2.00
GPT-5.1 Chat
Output price
Lower recorded price
GPT-5.1 Chat:$10.00
GPT-5.6 Terra:$12.00
GPT-5.1 Chat
Output speed
Higher recorded throughput
GPT-5.1 Chat:—
GPT-5.6 Terra:—
No complete comparison
Time to first token
Lower recorded latency
GPT-5.1 Chat:—
GPT-5.6 Terra:—
No complete comparison
Intelligence Index
Higher directory index
GPT-5.1 Chat:—
GPT-5.6 Terra:—
No complete comparison
Evidence
A score appears only when both records include a verified source. It is not treated as a universal ranking.
Specifications
| Specification | GPT-5.1 Chat | GPT-5.6 Terra |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Model family | gpt-codex | gpt-terra |
| Accepted inputs | text, image | text, image, pdf |
| Produced outputs | text | text |
| Context window | 128K | 1.1MRecorded lead |
| Max output | 16.4K | 128KRecorded lead |
| Intelligence Index | — | — |
| Input price / 1M | $1.25Recorded lead | $2.00 |
| Output price / 1M | $10.00Recorded lead | $12.00 |
| Output speed | — | — |
| Time to first token | — | — |
| Reasoning mode | Documented | Documented |
| Tool calling | Documented | Documented |
| Image input | Documented | Documented |
| Audio input | Not documented | Not documented |
| Structured output | Documented | Documented |
| License | Proprietary | Proprietary |
| Released | Nov 13, 2025 | Jul 9, 2026 |
Workload guidance
On the published numbers, GPT-5.6 Terra accepts the larger context window and GPT-5.1 Chat is cheaper per input token. Which matters more depends on whether your bottleneck is document size or spend — the table above has the exact figures.
Provenance
Prices and hosted performance can change. SyncDev records source references and clearly separates documented specifications from measured values; confirm commercial terms with the provider before deployment.
GPT-5.1 Chat
OpenAI · model record and recorded source
GPT-5.6 Terra
OpenAI · model record and recorded source
Choose any two approved model records and review them with the same evidence rules.