AI Context Window Planner
Estimate input room, output reserve, overlap, and chunk count before sending long text to AI.
Context window planner workspace
Estimate whether source text fits an AI context window.
Source text
Context plan
Plan result
176 input tokens6400 available1 chunks
Text fits
The estimated input fits after reserving output and system prompt space.
Token planning uses local estimates only. No text is uploaded.
Questions
Are context-window calculations exact?
No. They are local estimates based on text length and should be treated as planning guidance.
Why reserve output tokens?
A model response also consumes context, so leaving no output room can break long-prompt workflows.
Does Utilumo upload my input?
No. This tool is designed for local browser processing and does not send your input to a server.
Do I need an account?
No. Utilumo tools are built to work without accounts or sign-in.