GPT-5.5 Pro vs GPT-6 Astra
GPT-6 Astra leads the LLM Stats Score 60.3 to 44.9. GPT-6 Astra is 3.4x cheaper per token.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT-6 Astra leads the overall LLM Stats Score 60.3 to 44.9, ranking #1 overall.
In the 1 individual benchmarks reported for both models, GPT-6 Astra wins 1; this is a narrower head-to-head signal than the composite indexes.
On price, GPT-6 Astra is roughly 3.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5.5 Pro
- you want predictable pricing at $30.00/M input and $180.00/M output
Choose GPT-6 Astra
- overall performance matters — it scores 60.3 and ranks #1 on LLM Stats
- your work emphasizes reasoning — it leads those capability indexes
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
- cost matters — it's about 3.4x cheaper per token
- you want the most recent training data — it shipped Sep 2026
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
5 reported for GPT-5.5 Pro · 22 for GPT-6 Astra
GPT-5.5 Pro outperforms in 0 benchmarks, while GPT-6 Astra is better at 1 benchmark (BrowseComp).
GPT-6 Astra significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.5 Pro ($30.00/1M tokens) is 3.0x more expensive than GPT-6 Astra ($10.00/1M tokens).
For output processing, GPT-5.5 Pro ($180.00/1M tokens) is 3.6x more expensive than GPT-6 Astra ($50.00/1M tokens).
In conclusion, GPT-5.5 Pro is more expensive than GPT-6 Astra.*
* 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
Documented input modalities across available providers
Both GPT-5.5 Pro and GPT-6 Astra support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.5 Pro
GPT-6 Astra
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-5.5 Pro was released on 2026-04-23, while GPT-6 Astra was released on 2026-09-04.
GPT-6 Astra is 4 months newer than GPT-5.5 Pro.
Apr 23, 2026
4 months ago
Sep 4, 2026
6 days ago
4mo newerKnowledge Cutoff
When training data ends
GPT-5.5 Pro has a knowledge cutoff of 2025-12-01, while GPT-6 Astra has a cutoff of 2026-04-30.
GPT-6 Astra has more recent training data (up to 2026-04-30), making it potentially better informed about events through that date compared to GPT-5.5 Pro (2025-12-01).
Dec 2025
Apr 2026
4 mo newerProvider Availability
GPT-5.5 Pro is available from OpenAI. GPT-6 Astra is available from OpenAI.
GPT-5.5 Pro
GPT-6 Astra
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.5 Pro and GPT-6 Astra side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.5 Pro vs GPT-6 Astra.