Estimate chatbot AI cost before your bill surprises you
Enter your chatbot's expected usage to get a Low / Likely / High monthly API cost estimate. Everything runs locally in your browser — no data is sent to any server.
- No login
- No credit card
- No API calls
- Estimate only
Configure your chatbot
Estimated monthly cost
This is an estimate, not a billing guarantee. Actual costs depend on your provider's exact tokeniser, real conversation lengths, and your billing tier.
How this estimate works
- System prompt
- Current user message
- Chat history
- Knowledge base context
Reads everything you send, then writes a reply.
The model's reply. Output tokens usually cost 3–10× more than input.
Knowledge base context counts as extra input. This calculator assumes one retrieval per conversation — if your system retrieves on every message, real cost is higher.
Why history increases cost
Each new message re-sends the whole conversation so far, so later messages keep paying for earlier ones.
A 5-message chat costs far more than 5× one message. The Likely default — 1,650 input tokens — reflects this; ignoring history underestimates cost by 3–5×.
Low / Likely / High explained
Short messages, short answers, 1 prior turn of history retained.
Mid-range assumptions from the T9 methodology. Plan against this number.
Longer messages and answers, 5 prior turns of history. Budget against this.
Cut your cost
Example monthly costs
These worked examples use the same default assumptions as the calculator above — a standard system prompt, medium-length messages and answers, 5 messages per conversation, no knowledge base — with GPT-5.4 Mini. Only the number of conversations per month changes between rows. Use the calculator above to model your own usage or a different model.
| Usage level | Conversations / month | Low | Likely | High |
|---|---|---|---|---|
| Light usage | 200 | $0.9780 | $1.60 | $2.50 |
| Typical usage | 1,000 | $4.89 | $7.99 | $12.52 |
| Heavy usage | 5,000 | $24.45 | $39.94 | $62.62 |
Caveats
- These estimates use the formula characters ÷ 4 ≈ tokens, accurate to ±10–15% for plain English text.
- Each provider uses a different tokeniser. Actual token counts may differ ±5–10% between OpenAI, Anthropic, Google, Mistral, and DeepSeek for the same content.
- If your chatbot handles Portuguese or Spanish conversations, expect 10–25% higher token counts than shown — these languages tokenise less efficiently than English.
- Prices shown are manually verified against each provider's official pricing page as of 2026-09-08. AI provider pricing changes frequently — verify at your provider's official pricing page before making budget decisions.
- Model prices and context windows are checked directly against each provider's own pricing page and model documentation before being added here — see the pricing reference for the verification date and sourcing approach.
- Knowledge base costs assume one retrieval per conversation. If your system retrieves fresh content on every message, multiply the KB cost by the number of messages.
- The context-window warning above appears when the High scenario's combined tokens exceed 80% of the selected model's context window — a safety margin before truncation or failure risk, not a hard limit at 100%.
This is an estimate, not a billing guarantee. Always confirm against your provider's usage dashboard and official pricing before committing a budget.