Claude Code Context Window: What's Using Your Space and How to Fix It

Imagine this: you sit down after work, beverage of choice in hand after a long day. You start up Claude Code in the project you've been working on for weeks and type a message or two.

And now your available context is already smaller than you think.

What the...? I mean, you just started typing.

Is it the Incredible Shrinking Context Window? Not really, but this Claude Code tutorial on context may surprise you.

I believe most of us are familiar with the CLAUDE.md file. It's the configuration file we use to give Claude Code project context, documentation links, instructions, and items to remember about the project itself across sessions. Every time you begin a new session, the CLAUDE.md file is automatically loaded into your project context, eating away at its availability.

This is why it's important to evaluate your CLAUDE.md file from time-to-time to ensure it only contains the information your project truly needs, and to keep it at 500 lines or less, a recommendation directly from Anthropic's Claude Code documentation.

Aside from the CLAUDE.md file, there's another file that can fill up quickly, and it's Claude Code's auto memory file (MEMORY.md). The first 200 lines of the auto memory file is loaded at the beginning of each session, and Claude Code writes information there that it deems important enough to remember across sessions. What it doesn't do well, however, is keep it to 200 lines or less. To give you an example, I just asked Claude Code to check MEMORY.md for my current project and it was a whopping 610 lines. Everything after the first 200 lines is not automatically loaded on session start, but it's efficient to keep the file as clean as possible.

What I do periodically is ask Claude Code what's in its auto memory file. It self-analyzes and, in my situation, it pared down the auto memory file to include only necessary information that should be remembered across sessions and it moves all ancillary data into a separate markdown file that is linked from the auto memory file.

Or, if you want to see what's in your memory files, simply run the /memory skill. You'll be prompted to select one of the memory files available to see its contents. Once selected, Claude Code will open the file in an external editor. The /memory skill also shows you where each file is stored in your environment.

So the next time you think Claude Code isn't remembering things it should remember, or you feel as if your context is being eaten before you've even had a chance to start, have it examine its CLAUDE.md and MEMORY.md files. You just might find some context savings.

Preparing for the CCA exam? Start with our overview: What Is Anthropic's Claude Certified Architect Exam?