---
id: "2024-12-20-openai-o3"
url: "https://postcutoff.com/e/2024-12-20-openai-o3/"
as_of: "2026-11-13T13:49:00+01:00"
date: "2024-12-20"
date_precision: day
category: benchmark
importance: 5
confidence: high
status: [Confirmed]
sources: 2
editor: human editor
human_review: null
version: "2026-10-04"
---

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/2024-12-20-openai-o3/

# OpenAI announces o3, scoring 75.7–87.5% on ARC-AGI

On the last day of its '12 Days of OpenAI', OpenAI previewed o3, which scored 75.7% on the ARC-AGI semi-private set (87.5% with high compute) — a benchmark on which earlier LLMs scored in single digits — and 25.2% on FrontierMath.

## Key facts
- Announced 20 December 2024
- ARC-AGI-1 semi-private: 75.7% (high-efficiency), 87.5% (high-compute), verified by ARC Prize
- FrontierMath: 25.2% vs. under 2% for previous models, per OpenAI
- o3 and o4-mini released publicly on 16 April 2025, with full tool use

## What happened

Only three months after o1, OpenAI showed that scaling RL and test-time compute produced another large leap in reasoning.

## Why it matters

Convinced many observers that reasoning models were on a steep trajectory; ARC Prize called it a genuine step-change.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): in its training data
- Claude Opus 5.5 (training cutoff June 2026): in its training data
- Gemini 4 Hydrogen (training cutoff March 2026): in its training data
- Grok 4.7 (training cutoff May 2026): in its training data

## Sources

1. [OpenAI o3 Breakthrough High Score on ARC-AGI-Pub (ARC Prize)](https://arcprize.org/blog/oai-o3-pub-breakthrough) (arcprize.org, official)
2. [Introducing OpenAI o3 and o4-mini (OpenAI)](https://openai.com/index/introducing-o3-and-o4-mini/) (openai.com, official)

## Changes

- 2026-09-29 (filed): Created

## Related

- 2024-09-12: [OpenAI o1: reasoning models trained with reinforcement learning](https://postcutoff.com/e/2024-09-12-openai-o1/index.md)