# What is Context window?

Source: https://mushbloom.uk/resources/glossary/what-is-context-window.html

By Mushbloom. Published and updated: 2026-10-12.

## Definition & overview

A context window is the amount of input and output information a model can consider in one interaction, measured in tokens. A larger window does not guarantee that every supplied detail is used correctly.

## Analogy & mental model

It is the size of an assistant’s working desk, not their ability to remember every paper on it.

Supply focused, relevant evidence rather than pasting an entire unfiltered company archive.

## Why it matters

Context limits affect how much evidence a model can use in a single interaction. Overloading the input can add cost and irrelevant material without improving accuracy. Good retrieval and concise instructions often matter more than selecting the largest available window.

## Practical business example

A support assistant receives the current returns policy and the customer’s order details instead of thousands of unrelated support tickets.

Illustrative scenario, not a client case study or promised result.

## How it works

1. Estimate the space required by instructions, retrieved passages and expected output.

2. Select evidence relevant to the current task rather than an entire archive.

3. Test answers involving facts placed in different parts of the supplied context.

## Core components

- Input tokens

- Output budget

- Evidence selection

Available context capacity does not guarantee reliable use of every detail.

## Context window vs Knowledge base

The knowledge base is the wider stored collection. The context window is the limited working information supplied during a particular model interaction.

## Frequently asked questions

What does Context window mean?
A context window is the amount of input and output information a model can consider in one interaction, measured in tokens. A larger window does not guarantee that every supplied detail is used correctly.

How is it different from Knowledge base?
The knowledge base is the wider stored collection. The context window is the limited working information supplied during a particular model interaction.

What is a sensible first step for a small business?
Supply focused, relevant evidence rather than pasting an entire unfiltered company archive. Estimate the space required by instructions, retrieved passages and expected output.

What limitations should I keep in mind?
Available context capacity does not guarantee reliable use of every detail.

## Sources

Google Cloud: Retrieval-augmented generation: https://cloud.google.com/use-cases/retrieval-augmented-generation

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