GPT-5 Arrives in Microsoft Copilot: What You Need to Know

Copilot Aug 13, 2025

Microsoft rolled out GPT-5 to Microsoft 365 Copilot starting in August 2025, and the model has continued to evolve significantly since then. What started as GPT-5 has progressed through several iterations, and as of early 2026 the current versions available are GPT-5.3 Instant and GPT-5.4 Thinking. This post covers what the GPT-5 family of models brings to your day-to-day Copilot experience, how the model selector works, and what to expect from the different reasoning modes.

What GPT-5 Brought to Copilot

GPT-5 was a meaningful upgrade over the models that powered Copilot before it. The most noticeable improvement for most users is response quality on complex, multi-step tasks. GPT-5 handles ambiguous instructions better and is less likely to produce confident-sounding but incorrect answers. For the kinds of tasks Copilot handles in Word, Excel, and Teams, this translates to outputs that need less editing and fewer follow-up corrections.

A few specific improvements that made an immediate practical difference:

• Better performance on long documents. GPT-5 can hold significantly more content in its working context, which means fewer cases where Copilot seems to forget what was in the file you uploaded or misses something from earlier in a document.

• Improved reasoning on structured tasks. Creating formulas in Excel, building structured summaries, and handling multi-step workflows all benefit from the improved reasoning capability.

• Faster responses on simpler tasks. GPT-5's routing technology sends straightforward requests to a faster sub-model, so basic tasks like short email drafts or simple summaries come back quicker than before.

How the Model Has Evolved: GPT-5.2 through GPT-5.4

Since the initial GPT-5 rollout, Microsoft has pushed several updated versions through Copilot:

• GPT-5.2 rolled out in December 2025 and introduced the model selector, letting users choose between different reasoning modes for the first time.

• GPT-5.3 Instant launched in early 2026, optimized for speed. Best for quick tasks where you want a fast response over deep reasoning.

• GPT-5.4 Thinking launched in March 2026, adding a dedicated deep reasoning mode for complex analysis, long documents, and multi-step problems.

The rollout is complete. There is no longer a staged wait for access. All users with a Microsoft 365 Copilot license have access to the full model selector.

The Model Selector and Reasoning Modes

As of January 2026, the model selector is available across all Copilot surfaces: web, Windows, Mac, iOS, and Android. When you open Copilot Chat, you will see a model selector that lets you choose how you want Copilot to approach the conversation. There are three modes:

• Auto: This is the default. Copilot picks the right model for the task automatically based on what you ask. For most everyday use, this is the right choice.

• Quick Response (GPT-5.3 Instant): Prioritizes speed. Good for simple drafts, quick summaries, or when you are iterating fast and do not need deep reasoning.

• Think Deeper (GPT-5.4 Thinking): Uses more processing time to reason through complex problems. Good for analyzing long documents, working through ambiguous instructions, or tasks where quality matters more than speed.

For standard day-to-day Copilot use, leaving it on Auto gives you the best balance. Switch to Think Deeper when you are working on something complex and have a moment to wait for a more thorough response.

What This Means Across Microsoft 365 Apps

GPT-5 and its successors power Copilot across the full Microsoft 365 suite. The model selector is available in Copilot Chat, and the underlying model improvements flow through to the integrated Copilot experiences in Word, Excel, PowerPoint, Outlook, and Teams as well. You do not need to do anything in the individual apps; the model improvements apply automatically.

Declarative agents built in Copilot Studio also received an automatic upgrade to GPT-5.2, and the model selector is available there as well for custom agent configuration.

What Changes for Admins

The GPT-5 rollout does not require any admin action to enable. The model updates automatically for all licensed Copilot users. There are no new licensing costs for GPT-5 access, including the Think Deeper reasoning mode.

If your organization needs to maintain a specific model version for compliance or testing purposes, that is a conversation with your Microsoft account team. Standard admin center settings do not include per-model controls for the core Copilot experience.

Frequently Asked Questions

Is GPT-5.4 Thinking available on mobile?

Yes. The model selector including Think Deeper mode is available on iOS and Android as of January 2026.

Does using Think Deeper cost extra?

No. All reasoning modes are included in the standard Microsoft 365 Copilot license. There is no additional cost for Think Deeper or any of the model versions.

Can I set Think Deeper as my default instead of Auto?

The default is Auto and cannot be changed to a different mode persistently at the user level. You select the mode per conversation. If you consistently need deeper reasoning, building that into your workflow (always switching to Think Deeper before complex sessions) is the current approach.

How is this different from the Reasoning feature in Copilot?

Think Deeper mode is the publicly named version of the reasoning capability. When you select it, Copilot takes more time to think through the problem before responding, which shows up as a visible reasoning step in some interfaces. The result is generally more accurate and better structured for complex tasks.

Final Thoughts

The progression from the initial GPT-5 rollout to the current GPT-5.4 Thinking has made Copilot meaningfully more capable in a short period of time. The model selector gives users actual control over the quality/speed tradeoff for the first time, which is a practical improvement for people who know when they need depth versus when they just need a quick answer. If you have not experimented with Think Deeper mode yet, throw a complex document or a multi-part analytical question at it and see what you get.