Fast mode in Claude Code: enabling it, payment, and disabling it

For explanations of tool settings, see the Ailoot documentation.

What does fast mode change in Claude Code?#

As of the date of the check, the documentation lists Opus 5.5, Opus 5 and Opus 4.8. Sonnet and Haiku are not supported. The feature is in preview: prices and availability may change. The differences in the model itself are covered separately in the Opus 5.5 overview.

Check payment before enabling it#

On Pro, Max, Team and Enterprise subscriptions, fast mode consumes usage credits (credits for additional usage) and is charged separately from the included limits, even when you have not used up the included allowance. On Pro/Max, credits are enabled in Settings > Usage on claude.ai; the /usage-credits command opens that page. On Team/Enterprise, organization settings and the owner's permission are required.

In Claude Console, requests are billed through the API. The organization needs a paid account and access to fast mode; a client setting alone is not enough. Third-party platforms such as Amazon Bedrock are not supported.

According to the documentation checked on 24 September 2026, one million input tokens for Opus 5.5 cost 8 dollars, and output tokens cost 40 dollars; for Opus 5 and 4.8, the respective prices are 10 and 50 dollars. These are fast mode rates, not subscription prices. When fast mode is first enabled in a conversation, its entire context is charged at the full fast mode input-token rate without caching. A long conversation is therefore a poor place to switch modes accidentally.

For additional material on working with AI tools, see the Ailoot guides.

Enable the mode and check it#

1. In the interactive Claude Code terminal, enter /fast.
2. Press Space to toggle the setting and Enter to confirm.
3. Wait for Fast mode ON and the ↯ icon next to the input field. Running /fast again lets you check the status.
4. Run a short task. The icon alone does not mean the entire task will finish faster: assess how long you wait for a response in your own example.
5. After you finish, run /fast again and disable the mode. Run /fast once more to check that it is off.

Enabling fast mode while using an unsupported model switches Claude Code to Opus. In version 2.1.280 and later, the default fast mode model is Opus 5.5. When you disable the mode, you remain on Opus; use /model to choose another model. The Sonnet and Opus comparison can help you choose a model for your budget.

How to avoid leaving acceleration enabled#

By default, fast mode enabled in an interactive session stays enabled in subsequent sessions. To make each new session start without fast mode, add this key to your existing Claude Code settings file without replacing the whole file:

{
  "fastModePerSessionOptIn": true
}

You will then need to enable acceleration explicitly with /fast in each session. This is different from the temporarily grey icon shown during a rate limit.

What to do when it is unavailable#

• Fast mode requires usage credits: check that usage credits are enabled before repeating the command.
• Fast mode has been disabled by your organization: contact the organization owner; the user toggle does not give you permission to bypass its settings.
• A grey ↯: when the fast mode limit is reached, Claude Code temporarily returns to the normal speed and price, then enables acceleration again after a pause. If you no longer need it, turn it off manually.
• A network check error: access to normal responses does not confirm access to fast mode. Check the connection with your administrator rather than changing network protections at random.

On Pro/Max, usage-credit spending is visible in Settings > Usage, but fast mode is not shown separately there. Do not therefore treat a whole month's credit spending as the acceleration cost of a single session. There is a separate article on tracking usage: Claude Code token trackers.

In the source material, the commands above were checked against the documentation; no paid comparative speed benchmark was performed for this article. Start with a short task only when you understand the separate charge.