How AI API pricing works
Most large language model APIs price separately for input tokens (the prompt you send) and output tokens (the text the model generates). Input tokens are usually cheaper than output tokens because generating text requires more compute than reading it. Prices are typically listed per 1 000 or per 1 000 000 tokens depending on the provider.
A token is roughly four characters of English text, so 1 000 tokens is about 750 words. A short user question might use 50–100 tokens, while a complex prompt with context and instructions can use several thousand. Completion length depends on how verbose the model response needs to be.
Monthly requests = Requests/user/day × Users × Working days/month
Total API calls per month driven by user activity.
Input cost = (Prompt tokens × Monthly requests / 1000) × Price per 1K input
Total cost of tokens sent to the model each month.
Output cost = (Completion tokens × Monthly requests / 1000) × Price per 1K output
Total cost of tokens generated by the model each month.