Model Comparison
GPT-5.6 Terra vs GPT-5.5Which is better in 2026?
GPT-5.6 Terra shows notably better performance in the majority of benchmarks. GPT-5.6 Terra is 2.0x cheaper per token.
Verdict: GPT-5.6 Terra vs GPT-5.5 — which is better?
GPT-5.6 Terra (by OpenAI) and GPT-5.5 (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
GPT-5.6 Terra outperforms in 6 benchmarks (BrowseComp, FrontierMath, GDPval-AA, Graphwalks BFS >128k, MRCR v2 (8-needle), SWE-Bench Pro), while GPT-5.5 is better at 3 benchmarks (GPQA, MMMU-Pro, Toolathlon). GPT-5.6 Terra shows notably better performance in the majority of benchmarks.
On price, GPT-5.6 Terra is roughly 2.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Choose GPT-5.6 Terra if…
- you want the strongest raw capability — it leads on 6 of 9 shared benchmarks
- cost matters — it's about 2.0x cheaper per token
- you want the most recent training data — it shipped Jul 2026
Choose GPT-5.5 if…
- you want predictable pricing at $5.00/M input and $30.00/M output
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.6 Terra outperforms in 6 benchmarks (BrowseComp, FrontierMath, GDPval-AA, Graphwalks BFS >128k, MRCR v2 (8-needle), SWE-Bench Pro), while GPT-5.5 is better at 3 benchmarks (GPQA, MMMU-Pro, Toolathlon).
GPT-5.6 Terra shows notably better performance in the majority of benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.6 Terra ($2.50/1M tokens) is 2.0x cheaper than GPT-5.5 ($5.00/1M tokens).
For output processing, GPT-5.6 Terra ($15.00/1M tokens) is 2.0x cheaper than GPT-5.5 ($30.00/1M tokens).
In conclusion, GPT-5.5 is more expensive than GPT-5.6 Terra.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Both models have the same input context window of 1,050,000 tokens. Both models can generate responses up to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both GPT-5.6 Terra and GPT-5.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.6 Terra
GPT-5.5
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
GPT-5.6 Terra was released on 2026-07-09, while GPT-5.5 was released on 2026-04-23.
GPT-5.6 Terra is 3 months newer than GPT-5.5.
Jul 9, 2026
1 weeks ago
2mo newerApr 23, 2026
2 months ago
Knowledge Cutoff
When training data ends
GPT-5.6 Terra has a knowledge cutoff of 2026-02-16, while GPT-5.5 has a cutoff of 2025-12-01.
GPT-5.6 Terra has more recent training data (up to 2026-02-16), making it potentially better informed about events through that date compared to GPT-5.5 (2025-12-01).
Feb 2026
2 mo newerDec 2025
Provider Availability
GPT-5.6 Terra is available from OpenAI. GPT-5.5 is available from OpenAI.
GPT-5.6 Terra
GPT-5.5
Outputs Comparison
Key Takeaways
GPT-5.5
View detailsOpenAI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.6 Terra and GPT-5.5 side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT-5.6 Terra vs GPT-5.5.