Question 1

How does OpenAI charge for API usage?

Accepted Answer

OpenAI charges separately for input tokens (your prompt) and output tokens (the response). Prices vary by model — GPT-4o costs $2.50/1M input tokens and $10/1M output tokens, while GPT-4o mini is much cheaper at $0.15/1M input and $0.60/1M output.

Question 2

What is a token in GPT?

Accepted Answer

A token is roughly 4 characters or ¾ of a word in English. The sentence 'Hello, how are you?' is about 6 tokens. Most API requests use between 100–2000 tokens for input and 100–1000 for output.

Question 3

How can I reduce my OpenAI API costs?

Accepted Answer

Switch to GPT-4o mini for simpler tasks (it's ~16x cheaper), implement caching for repeated prompts, reduce prompt verbosity, use streaming to stop generation early, and batch requests where possible.

Question 4

Is GPT-4o mini good enough for most use cases?

Accepted Answer

Yes — GPT-4o mini performs excellently for most tasks like summarization, classification, simple Q&A, and coding assistance. Use GPT-4o only for complex reasoning, nuanced writing, or tasks where output quality is critical.

Question 5

Does this calculator include all OpenAI API costs?

Accepted Answer

This calculator covers text generation (chat completions) costs. OpenAI also charges separately for embeddings, image generation (DALL-E), speech-to-text (Whisper), and fine-tuning. Add those in if applicable.

GPT API Cost Calculator — Free OpenAI Pricing Tool

Frequently Asked Questions

From the Blog