What an AI API costs a small business
An API is paid by tokens, not by the month. This guide shows how to estimate the bill from the number of messages, which models are cheap and which are flagships, and when a subscription comes out cheaper.
Updated 5 October 2026 · prices in the text are today's
What a token is
A token is a piece of a word; Czech usually splits into more tokens than English text of the same length. An API price list states two prices: per million input tokens (what you send the model) and per million output tokens (what the model writes). Output costs more than input on every model.
A typical customer-support message carries about 1,500 input tokens (question, history and instructions) and 600 output tokens (the answer).
How to count a month
1,000 messages a day is 30,000 messages a month, that is 45 million input and 18 million output tokens. Bill = 45 × price per 1M input + 18 × price per 1M output.
The calculator on the AI API page computes the same for your number of messages and for all models at once. Cached input (repeated instructions) and batch processing lower the price further; each model lists its discount.
Cheap and flagship models
The cheap tier: GPT-6 Luna API (CZK 0.09 / CZK 0.45 per 1M tokens), Gemini 3.5 Flash-Lite API (CZK 0.27 / CZK 2.23 per 1M tokens), DeepSeek V4.1 Flash API (CZK 0.27 / CZK 1.07 per 1M tokens) and Claude Haiku 4.5 API (CZK 0.89 / CZK 4.45 per 1M tokens). Enough for sorting e-mails, summaries and simple answers.
Flagships: Claude Opus 5.5 API (CZK 3.56 / CZK 17.82 per 1M tokens) and GPT-6 Astra API (CZK 8.91 / CZK 44.54 per 1M tokens). The price per token can be a hundred times that of the cheap tier (compare Luna and Astra); it pays where a mistake costs more than the tokens, such as contracts or code.
Subscription or API
For one person who writes and codes with AI a subscription such as Claude Pro (€18 a month) or ChatGPT Plus (€17.82 a month) comes out cheaper: a fixed price whatever the number of messages, up to the limit. The API pays off when AI answers automatically (a shop, support, document processing) and nobody sits at it.
A subscription cannot power an automated service on your website; only the API can. API prices are in dollars; the token in the text converts them to your currency.
Fordeal earns a commission when you buy through a link; it never changes the order of offers. Every price carries its capture time on the product page.