> ## Documentation Index
> Fetch the complete documentation index at: https://docs.inferencelab.co/llms.txt
> Use this file to discover all available pages before exploring further.

# Reasoning effort

> Instant, Low, Medium, High — the four levels of how hard reasoning models think.

Reasoning models can think for milliseconds or for many seconds. Foundry exposes that choice as a four-level dial in **Settings → Reasoning Effort**.

<Note>
  **Pro feature.** Reasoning Effort is available on Pro plans.
</Note>

<Note>
  **Screenshot coming.** Effort dropdown.
</Note>

## The four levels

| Level | When to use | What it buys you |
| - | - | - |
| **Instant** | Quick lookups, casual replies | No reasoning. Fastest. Cheapest. |
| **Low** | Light synthesis, simple multi-step | Brief reasoning trace. Snappy. |
| **Medium** | Coding, analysis, comparisons | Balanced. The default for serious work. |
| **High** | Hard math, long planning, complex research | Deepest trace. Slowest. Highest token cost. |

The dial applies to **every routed reply** until you change it.

## What "instant" means

`Instant` turns reasoning **off**, even when the routed model is reasoning-capable. The reply behaves like a regular chat completion. The Reasoning block doesn't render.

## Picking a level

Most people pick **Medium** and leave it there. Move to **High** for one-off hard problems, **Low** when you want speed, **Instant** when you don't want any thinking.

The footer of every reply tells you which level was used so you can audit cost and latency.

## Limits

* Reasoning Effort only affects **reasoning-capable** models. If the router picks a non-reasoning model for your prompt, the level is ignored.
* High runs can take 30+ seconds on the hardest prompts. Pair with [browser notifications](/foundry/chat/notifications) so you don't sit and watch.

## Related

<CardGroup cols={2}>
  <Card title="Live reasoning view" icon="eye" href="/foundry/reasoning/live-view">
    Watch the trace stream.
  </Card>

  <Card title="Reasoning models" icon="brain" href="/foundry/reasoning/overview">
    Concept overview.
  </Card>
</CardGroup>


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