---
title: Choosing a tier
description: Auto, Fast, Smart and Max — what each one is for, what actually divides them, and which kind of job belongs on which.
---

The engine menu in the composer offers four choices, and the shortest useful answer is:
**leave it on Auto until a specific run gives you a reason not to.** The other three are
there for when you have that reason.

The menu itself is the definition. It reads, word for word:

| Choice | What the menu says it is | Detail |
| --- | --- | --- |
| **Auto** | Best value for each request | picks among the three below |
| **Fast** | Cheapest acceptable answer | [The Fast tier](/docs/tiers/fast) |
| **Smart** | Balanced quality, long context | [The Smart tier](/docs/tiers/smart) |
| **Max** | Deepest reasoning | [The Max tier](/docs/tiers/max) |

## What the tiers are actually dividing

Notice what those four lines are *not* about. They are not four price points, and they are
not four speeds — despite everyone, us included, slipping into calling them that. Each tier
is named for **the kind of answer it is trying to buy** — cheapest acceptable, balanced,
deepest — and the price follows from that rather than defining it.

That distinction is load-bearing, because each of the three named tiers runs one particular
model by default, and swapping which model a tier points at changes what that tier costs
without changing what the tier is *for*. **So a tier name on its own is never a price.** Each
tier's own page — [Fast](/docs/tiers/fast), [Smart](/docs/tiers/smart), [Max](/docs/tiers/max) — names the
model it runs and its rate together, and [Model prices](/docs/model-prices) has the full table.
Those pages are generated from the same source the product itself reads, which is why this
page sends you there instead of repeating a number that would quietly drift.

**Auto is the fourth thing, not a fourth level.** It does not sit between Smart and Max.
It reads the request you actually sent and picks among the three tiers for you — so what
Auto costs depends on what you asked. A one-line question and a research job both sent on
Auto will not land on the same tier and will not cost the same. We are not going to
publish the rule it uses, partly because it changes, but the observable behaviour is the
part you can rely on: **Auto varies by request, and Auto is what every reply's receipt
records when you leave it alone.**

## Which job belongs where

**Leave it on Auto** for anything ordinary. Questions, drafting, tidying up a file,
research you haven't scoped yet. Auto is the default because for most of what people
actually send, deliberately picking a tier is a decision that costs more attention than
it saves money.

**Reach for [Fast](/docs/tiers/fast)** when you already know the answer is easy and there is
volume. Pulling fields out of a document you attached. Reformatting. Renaming forty things.
Anything where you would be able to tell instantly that the output is wrong, so a cheaper
attempt costs you nothing but the attempt.

**Reach for [Smart](/docs/tiers/smart)** when the job is long rather than hard. Its menu line says
*long context* and that is the signal: a big attachment, a chat that has been running for a
while, a document you want read end to end and summarised faithfully. Smart is also what a
handed-off task runs on when no engine was chosen for it.

**Reach for [Max](/docs/tiers/max)** when being wrong is expensive and you cannot check the answer
yourself quickly. A decision that turns on reasoning rather than retrieval. Code you are
going to run against something real. A document whose argument has to hold. Max is the one to
choose deliberately and then stop choosing — compare the three tier pages' rates before you
leave everything on it, because standing on the dearest tier is how a week gets costly for no
gain.

## The thing tiers do not fix

A tier is a choice about how well the thinking is done. It does not change how *much*
thinking a job needs, and on most bills the amount dominates the rate. A vague request
sent on Max costs more than a precise request sent on Max, by a wider margin than Max
costs more than Fast. If a run came back expensive, the tier is the second thing to look
at — see [Why it cost that much](/docs/why-it-cost-that-much), and
[Writing a good request](/docs/writing-a-good-request) for the first thing.

## Going below the tiers

Beneath the four tiers the menu offers **Pick an exact engine**, described as *"Every model
with real supply"* — a list of every individual model you can run, by name, with sort and
filter controls. That is the escape hatch for when you want a specific model rather than a
category. [Switching engines](/docs/switching-models) covers how to use it and what scope your
choice applies to; [Model prices](/docs/model-prices) is the full list with rates.

You can also point a tier at a different model permanently, so that *Smart* means something
else for you from then on. Whether you should is its own question — see
[Changing what a tier runs](/docs/changing-tier-defaults).

## Where to go deeper

This page is the overview: what the tiers mean and how to pick one. For a single tier's
specifics — the model it runs, its rate, a worked cost example, what happens when it cannot
run, and what we have not verified about it — go to that tier's own page:
[Fast](/docs/tiers/fast) · [Smart](/docs/tiers/smart) · [Max](/docs/tiers/max).