T9 Token Budget
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Guides for understanding AI costs

Practical explanations for tokens, model pricing, cost planning, and smarter AI usage.

Start here · Basics

What are AI tokens?

Input vs output tokens, what a context window is, and why these decide what you pay.

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More guides

Avoid surprises

Why is my AI API bill higher than expected?

The common reasons a bill grows — history, system prompts, output length, RAG context — and how to investigate and reduce the risk before launch.

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Related resources

Reference material and tools — not guides, but useful alongside them.

Reference Methodology — how we estimate Tools All four calculators, side by side

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