GPT-5.1 Instant vs GPT-6 Astra
GPT-6 Astra leads the LLM Stats Score 60.3 to 36.6. GPT-5.1 Instant is 5.8x cheaper per token.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT-6 Astra leads the overall LLM Stats Score 60.3 to 36.6, 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-5.1 Instant is roughly 5.8x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-6 Astra also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5.1 Instant
- cost matters — it's about 5.8x cheaper per token
Choose GPT-6 Astra
- overall performance matters — it scores 60.3 and ranks #1 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
- you process long inputs — it offers a 1,050,000 token context window
- 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
9 reported for GPT-5.1 Instant · 22 for GPT-6 Astra
GPT-5.1 Instant outperforms in 0 benchmarks, while GPT-6 Astra is better at 1 benchmark (GPQA).
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-5.1 Instant ($1.25/1M tokens) is 8.0x cheaper than GPT-6 Astra ($10.00/1M tokens).
For output processing, GPT-5.1 Instant ($10.00/1M tokens) is 5.0x cheaper than GPT-6 Astra ($50.00/1M tokens).
In conclusion, GPT-6 Astra is more expensive than GPT-5.1 Instant.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-6 Astra accepts 1,050,000 input tokens compared to GPT-5.1 Instant's 400,000 tokens. Both models can generate responses up to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both GPT-5.1 Instant and GPT-6 Astra support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.1 Instant
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-5.1 Instant was released on 2025-11-12, while GPT-6 Astra was released on 2026-09-04.
GPT-6 Astra is 10 months newer than GPT-5.1 Instant.
Nov 12, 2025
10 months ago
Sep 4, 2026
4 days ago
9mo newerKnowledge Cutoff
When training data ends
GPT-6 Astra has a documented knowledge cutoff of 2026-04-30, while GPT-5.1 Instant's cutoff date is not specified.
We can confirm GPT-6 Astra's training data extends to 2026-04-30, but cannot make a direct comparison without GPT-5.1 Instant's cutoff date.
—
Apr 2026
Provider Availability
GPT-5.1 Instant is available from OpenAI. GPT-6 Astra is available from OpenAI.
GPT-5.1 Instant
GPT-6 Astra
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.1 Instant and GPT-6 Astra side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.1 Instant vs GPT-6 Astra.