Prompt Token Estimator
Get a rough token and context-size estimate for a prompt without transmitting its content.
Free browser tool
No Matrix computer needed
✓ No account or card
✓ Use the result right away
✓ Task-specific limits below
Workspace
Use prompt token estimator
Runs in this browser tab
Result
How to use it
Paste a prompt to estimate its approximate token count using a simple text heuristic.
Try this example
Explain how Matrix keeps agents working when a laptop closes.
What to check
Actual tokenizer counts vary by model and format; use provider metering for billing.
Review the result before using it in a published page, application, or agent configuration.
Quick answers
Frequently asked questions
How does Matrix estimate prompt tokens?
It uses a rough character-based calculation. Actual counts depend on the model tokenizer, language, formatting, and tool messages.
Can I use this estimate to enforce a model limit?
Treat it as an early planning signal. Leave room for system instructions and outputs, then check the actual model or API count.
Keep exploring
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Need this work to keep going?
Matrix gives agents a private cloud computer for files, connected tools, and work that continues after you close your laptop. The browser tool above is free; a Matrix computer requires a paid plan.