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OpenAI expands GPT-5 context window to one million tokens

OpenAI expands GPT-5 context window to one million tokens

New Capabilities

Model processes more than 100 times more text per request than GPT-4, enabling single-request document and codebase generation

Yesterday: OpenAI unveils GPT-5 with million-token context

Overview

Updated 1 hour ago

OpenAI's GPT-5 can now process a million tokens in a single request, enough to absorb an entire manuscript or codebase at once. That is about 125 times the 8,000-token limit of GPT-4, the generation it builds on.

The larger window lets developers feed GPT-5 full research reports, complete codebases, or multi-chapter narratives in one prompt, instead of splitting inputs and stitching together outputs. OpenAI says reasoning, factuality, and instruction-following also improved. The move puts OpenAI on par with Google and Anthropic, which already ship million-token models.

Why it matters

A million-token context lets a single GPT-5 call digest a full codebase or book, collapsing multi-step AI pipelines into one request.

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Key Indicators

1,000,000
GPT-5 context window (tokens)
Maximum tokens GPT-5 can process per request.
125x
Context increase over GPT-4
Million-token window versus GPT-4's 8,000-token limit.
33%
Fewer false claims in GPT-5.4 vs GPT-5.2
On prompts users flagged for factual errors, per OpenAI's release notes.

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People Involved

Organizations Involved

Timeline

March 2023 October 2026

5 events Latest: Yesterday
Tap a bar to jump to that date
  1. OpenAI unveils GPT-5 with million-token context

    Latest Announcement

    OpenAI unveils GPT-5 with a one-million-token context, more than 100 times GPT-4's.

  2. GPT-5.5 reaches the API

    Release

    GPT-5.5 and GPT-5.5 Pro reach the API with a one-million-token window.

  3. GPT-5.4 ships with million-token context

    Release

    GPT-5.4 ships with a one-million-token context window and native computer-use in Codex.

  4. GPT-5 launches as OpenAI's flagship

    Launch

    GPT-5 launches as OpenAI's flagship with built-in reasoning, available to all users.

  5. GPT-4 launches with 8,000-token context

    Launch

    GPT-4 launches with an 8,000-token context window, the baseline for GPT-5.

Scenarios

1

Million-token context reaches all GPT-5 API tiers

Likely Resolves by Q2 2027

Discussed by: OpenAI developer documentation and Codex release notes

OpenAI has given GPT-5.4 experimental one-million-token support in Codex at double the standard usage rate, and GPT-5.5 a one-million-token API window. If developer demand holds, the full context opens to standard non-Pro tiers and appears in published API documentation.

2

Rivals undercut OpenAI on long-context pricing

Possible Resolves by Q2 2027

Discussed by: The Decoder, industry pricing trackers

Google and Anthropic already ship million-token models. OpenAI prices million-token usage at twice the standard rate in Codex and lists GPT-5.5 Pro at $30 per million input and $180 per million output tokens. If competitors undercut those rates, long-context work flows to them; if they match, a pricing contest follows.

3

Independent tests find GPT-5 accuracy slips at long context

Possible Resolves by Q2 2027

Discussed by: Third-party evaluation labs such as Artificial Analysis

OpenAI says GPT-5.4's claims are 33% less likely to be false than GPT-5.2's on flagged prompts. Whether accuracy holds at a million tokens, retrieving facts across a full codebase, is a separate question that independent evaluations will test as long-context use spreads.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

February 2024

Gemini 1.5 Pro (2024)

Google gave developers a one-million-token context window in its Gemini 1.5 Pro model, letting it process an entire book's worth of text or hours of video in one pass.

Then

Google demonstrated that million-token contexts were feasible and marketed Gemini's capacity against OpenAI's smaller windows.

Now

The one-million-token bar became the industry comparison point for long-context models.

Why this matters now

OpenAI's million-token window matches a threshold Google set years earlier, rather than setting a new one.

March 2023

GPT-4 launch (2023)

OpenAI released GPT-4 with an 8,000-token context window, up from roughly 4,000 in earlier GPT-3.5-era models.

Then

The larger window let developers build applications that could process longer documents and hold more instructions.

Now

Each context jump has unlocked new application categories, from document analysis to multi-step agents.

Why this matters now

GPT-4's 8,000-token limit is the baseline OpenAI now measures against; the million-token window is a 125-fold jump.

Sources

(6)