---
title: The Fast tier
description: The Fast tier runs gemini-3.6-flash by default — $1.80 per million input tokens and $9.00 per million output tokens. What lands here, what it costs, and what happens when it cannot run.
---

{/*
  ============================================================================
  DO NOT EDIT THIS FILE BY HAND. IT IS GENERATED, AND YOUR EDIT WILL BE LOST.

  Generated by : apps/platform/scripts/build-docs-model-guides.ts
                 (in the chatinone-platform repo)
  Generated from: packages/core/data/models.json  ->  pickerModels(CATALOG_MODELS)
                 apps/platform/src/model-routing.ts  (DEFAULT_TIER_BINDINGS)
  This page     : Fast tier

  To change anything below, change the source in that repo and re-run:
      pnpm --filter @chatinone/platform gen:docs-model-guides -- --write

  Committed snapshots live in that repo under
  apps/platform/test/fixtures/docs-model-guides/, and
  apps/platform/test/docs-price-table-drift.test.ts fails if a snapshot, or the
  SET of pages, disagrees with the regenerated output.

  Prices here are RETAIL — what you are actually charged. They come from the
  same projection the in-product engine picker is built from, so this page and
  the product cannot disagree.
  ============================================================================
*/}

**Fast** is one of four options in the composer's engine menu, alongside **Auto**, and the other two tiers. It exists to give you the cheapest acceptable answer.

## What it runs

The Fast tier runs `google/gemini-3.6-flash` by default, made by Google.

| Runs as | Input / 1M tokens | Output / 1M tokens |
| --- | --- | --- |
| **Fast** tier default | $1.80 | $9.00 |
| **Fast** tier default, repeated context | $0.18 | — |

The second row is the **repeated-context rate**. When a request re-sends context the model has already seen, those tokens are billed at that lower rate instead of the full input rate — it is applied automatically by the biller, not something you switch on. See [How billing works](/docs/how-billing-works).

You can point this tier at a different model in Settings → *How it works* → **Set an engine per speed tier**, and you can override it for a single request from **Pick an exact engine**.

## What lands here

Send work here when the answer is short, the material is small, and being right matters more than being thorough: rewriting a paragraph, extracting a few fields from a page you paste in, drafting a reply, classifying or tidying a list.

Work that does **not** belong here is anything with many steps that depend on each other, or anything where you would rather pay more than re-do it. That is what **Max** is for.

Two things this page deliberately does not tell you: how **Auto** decides, and how a request moves between models. Those are internal and we do not publish them. What we do publish is the above — pick a tier and you know which model runs and what it costs.

## What it costs on a real run

Both examples below run as the **Fast** tier default, at the two rates above:

| Runs as | Run shape | Cost |
| --- | --- | --- |
| **Fast** tier default | 4,000 in, 800 out (a short question with a little context) | **$0.0144** |
| **Fast** tier default | 100,000 in, 10,000 out (a long document and a long answer) | **$0.27** |

That is the whole arithmetic: tokens × the two rates. Nothing is rounded up, there is no per-run fee, and the receipt itemises every line. The ceiling on one request is this model's context window, 1M tokens (about 786,000 words, roughly 1.6k pages) — instructions, attachments and the answer all share it.

## What happens when it cannot run

If `gemini-3.6-flash` loses its price or its capacity, this tier does **not** silently run something else:

- If you had re-bound **Fast** to your own choice and that choice lost supply, the tier falls back to its own default and **tells you it did** — you get a notice naming what you asked for and what actually ran.
- If the default itself is unavailable too, the tier reports itself unresolved rather than borrowing another tier's model. There is no quiet cross-tier substitution.

This is the only failure behaviour we publish, because it is the only one we can point at in the code that implements it.

## What you will and will not notice

You will notice: which tier you are on (the engine menu shows it), a fallback when one happens (it is reported, not hidden), and every charge (itemised on the receipt — see [Reading a receipt](/docs/reading-a-receipt)).

You will not notice, because we do not expose it: how **Auto** chooses, or anything about where capacity comes from.

## What we have not verified

- We publish no measured speed for this tier. Tiers are named for what they are **for**, not for how fast they run: "Fast" is a meaning, not a benchmarked latency, and we have no timings we would stand behind.
- We publish no measured quality comparison between tiers. Nothing here claims Fast answers better or worse than another tier on your work.
- Image input on `gemini-3.6-flash` has **not** been measured. If you need to hand over a picture, use a model from [Models that can read your images](/docs/models-that/read-your-images) instead of assuming this tier can.

## Next

- [Model prices](/docs/model-prices) — every model and every price in one table
- The other tiers: [Smart](/docs/tiers/smart) and [Max](/docs/tiers/max)
- Start a run at [elsedoes.com/home](https://elsedoes.com/home)

**Prices last changed 2026-07-29** (source `ced6a4f`). Every figure here is generated from the same pricing code that bills your runs.