How much does an AI chatbot cost per month?

Short answer: for a simple website or support chatbot, the model bill ranges from under a dollar to a few thousand dollars a month, depending on traffic and model. For most small sites it is under $150. Long conversations and big knowledge-base snippets are what make it grow.

The example

One question and one answer: about 800 input tokens (instructions plus the visitor's question) and 300 output tokens (the reply). No caching. 30 days a month, list prices.

Why long conversations cost more

A chatbot has no memory of its own. To answer the 5th message, it is sent the whole conversation so far. So input grows with every turn. If the average chat has 5 turns and each turn sends about 2,400 input tokens, Claude Sonnet 5.5 at 1,000 chats a day goes from $138 to $1,170 a month.

Two easy fixes: summarise older messages instead of resending them word for word, and keep fixed instructions at the start of the prompt so prompt caching can discount them.

If your bot answers from your documents (RAG)

Bots that look up help articles paste the matching passages into every prompt. That can add a few thousand input tokens per answer. Send only the 2–3 most relevant passages, not whole pages.

Costs that aren't the model

• The chat widget or platform subscription, if you use one.
• Hosting and a database for chat logs.
• Your time reviewing answers, especially in the first weeks.

For most small businesses these are bigger than the token bill, so it's worth picking a model on quality first and then checking the price here.

Try your own numbers

Use the calculator with your chats per day and message length, or compare models side by side in our comparisons. More savings tips: How to reduce LLM token costs.

Prices are list prices per million tokens from our pricing table (last refresh 2026-11-02); check providers before you commit. This guide was written with help from AI tools and checked by a human. See also: model vs model cost comparisons and recent price changes.