---
id: "2026-09-03-arc-agi-3-gpt-6-astra"
url: "https://postcutoff.com/e/2026-09-03-arc-agi-3-gpt-6-astra/"
as_of: "2026-11-13T13:49:00+01:00"
date: "2026-09-03"
date_precision: day
category: benchmark
importance: 5
confidence: high
status: [Confirmed]
sources: 7
editor: human editor
human_review: null
version: "2026-10-05"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/2026-09-03-arc-agi-3-gpt-6-astra/

# GPT-6 Astra scores 62.7% on ARC-AGI-3, outacting humans on 96% of levels

Full title: GPT-6 Astra scores 62.7% on ARC-AGI-3 (99.9% with provider harness), outacting humans on 96% of levels

ARC Prize reported on 2026-09-03 that OpenAI's GPT-6 Astra scored 62.7% on ARC-AGI-3 (semi-private) with the standard harness ($26K) and 99.9% ($19K) with OpenAI's own provider-adapter harness, using fewer actions than the human baseline on 96% of levels; ARC Prize will now label both conditions separately.

## Key facts
- Standard harness: 62.7% at $26,098; Provider Adapter harness: 99.9% at $18,817
- Fewer actions than human baseline on 96.0% of levels; 51.7% fewer actions per level on average (provider harness)
- Human participants were paid ~ $12.78 per attempted game
- Other ARC-AGI-3 scores: Claude Opus 5 30.16% (Jul 24), Gemini 3.8 Flash 35.00%, GPT-5.6 7.78%, Grok 4.6 2.11% (leaderboard as of late Sept)
- Same leaderboard: GPT-6 95.0% on ARC-AGI-2; Claude Opus 5.5 93.3% (Sep 22)
- Later verified ARC-AGI-3 scores: GPT-6 Sol 4.6% standard / 23.0% provider harness (Sept 28); GPT-6.1 Sol 52.7% standard / 96.4% provider harness at $4.4K, 77% cheaper than Astra (Sept 30)
- Kaggle ARC Prize 2026 (open, compute-limited track): Tufa Labs retook 1st place at 45.33% on Sept 29; Milestone #2 prizes went to Daniel Franzen (27.9%), Lord Han Solo (23.8%) and Lohit Siriki (22.5%) on Oct 1
- ARC Prize is exploring next-generation benchmarks (recursive self-improvement, open-ended innovation)

## What happened

Six months after ARC-AGI-3 launched with frontier models near 0%, GPT-6 Astra reached 62.7% under the neutral harness. With OpenAI's context-management setup it reached 99.9%, a result the shared harness did not reproduce,
so ARC Prize now reports both. ARC Prize said Astra "builds the most precise symbolic model of novel environments we've seen."

## Why it matters

ARC-AGI-3 was meant to measure human-like skill acquisition; its near-saturation (and the harness gap) shows both how fast agentic reasoning improved in 2026 and how much scaffolding now drives scores.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): 126 days after its cutoff
- Claude Opus 5.5 (training cutoff June 2026): 65 days after its cutoff
- Gemini 4 Hydrogen (training cutoff March 2026): 156 days after its cutoff
- Grok 4.7 (training cutoff May 2026): 95 days after its cutoff

## Sources

1. [ARC Prize: OpenAI's GPT-6 Astra on ARC-AGI-3](https://arcprize.org/blog/astra) (arcprize.org, official)
2. [ARC Prize results leaderboard](https://arcprize.org/results) (arcprize.org, official)
3. [ARC Prize on X: GPT-6.1 Sol on ARC-AGI (Verified)](https://x.com/arcprize/status/2105391846067249649) (x.com, official)
4. [ARC Prize on X: GPT-6 Sol on ARC-AGI (Verified)](https://x.com/arcprize/status/2104671274299429283) (x.com, official)
5. [36Kr: GPT-6 scores 99.9%, ARC exam forced remake](https://eu.36kr.com/en/p/3985494895115010) (eu.36kr.com, press)
6. [ARC Prize on X](https://x.com/arcprize/status/2095597602545025138) (x.com, discussion)
7. [François Chollet on X: Astra a 'step-function change' on ARC-AGI-3](https://x.com/fchollet/status/2095598451115614371) (x.com, discussion)

## Changes

- 2026-10-04: Added GPT-6 Sol and GPT-6.1 Sol verified ARC-AGI-3 scores and Kaggle Milestone #2 results
- 2026-09-29: Added post link(s)
- 2026-09-29 (filed): Created

## Related

- 2026-10-01: [Open-source ARC-AGI-3 agents top out at 27.9% at ARC Prize 2026 Milestone #2](https://postcutoff.com/e/2026-10-01-arc-prize-2026-milestone-2-winners/index.md)
- 2026-09-29: [OpenAI releases GPT-6.1 Sol](https://postcutoff.com/e/2026-09-29-gpt-6-1-sol/index.md)
- 2026-03-25: [ARC Prize launches ARC-AGI-3, an interactive game benchmark where frontier AI scored under 1%](https://postcutoff.com/e/2026-03-25-arc-agi-3-launch/index.md)
- People: [François Chollet](https://postcutoff.com/person/francois-chollet/)
- Archived: 6 posts, listed in https://postcutoff.com/e/2026-09-03-arc-agi-3-gpt-6-astra/index.json