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

# Bottling: fill & mix

> How Saturday turns per-hour targets into real bottles

# Bottling: fill & mix

<div id="bottling-fill-mix" />

**What it is.** An athlete's Setup describes the vessels they carry, their **carriage**, and how each one is filled and mixed. Saturday maps the per-hour prescription onto that carriage, so the athlete knows what goes in each bottle and when to drink it.

**When to change it.** When the athlete's gear changes, such as more or fewer bottles, a bigger flask, or a feed zone on course. When a mix that is too concentrated is causing stomach trouble. When what they carry does not cover the session's duration.

**What the athlete gets.** A concrete bottle plan with fill volumes, scoop counts, and a drink cadence, with none of the math left to them.

**The question it answers.** *"How much do I put in each bottle, and how often do I drink?"*

## How carriage is structured

Carriage is stored per activity type, not globally. A cycling Setup and a running Setup are separate, each an ordered list of **slots**. A slot is one vessel with a maximum volume.

So "how many bottles" is the slot count for that activity type, and "how big" is each slot's volume ceiling.

<Note>
  **There is no concentration dial.** Concentration is an outcome, not an input. You set what the athlete carries and how large each vessel is; Saturday works out how much carbohydrate and sodium go into each one to hit the prescription. To make a mix less concentrated, give the athlete more fluid capacity to spread the same carbohydrate across.
</Note>

## What you do as a coach

* **Read it first.** Open the athlete's current carriage before changing anything, so you are adjusting from ground truth rather than a guess.
* **Edit the slots.** Pick the activity type, then add, remove, or resize slots. Saturday re-maps the consumption plan and shows a one-line impact preview as you go. See [The Setup](/coaching/nutrition/setup-dials).
* **Pre-fill for a new athlete.** For an athlete who is less comfortable with the app, you can dial in their bottling from your roster before they ever open it, so they arrive to a working plan.

## See also

* [The Setup](/coaching/nutrition/setup-dials) for where carriage lives and how to adjust it.
* [Gluc:fruc ratio](/coaching/nutrition/gluc-fruc-ratio) for what goes into the mix.
* [Eco-mode vs products](/coaching/nutrition/eco-mode-vs-products) for what you fill bottles with.