OpenAI Token Counter

This tool uses the standard approximation of 1 token ≈ 4 characters for English text. This closely matches the tiktoken tokenizer used by OpenAI for GPT-3.5 and GPT-4 models. For non-English text or code, actual token counts may differ — code tends to use more tokens per character and some languages use fewer characters per token.

GPT-4o supports a 128,000-token context window, which is roughly equivalent to about 300 pages of text. This massive context window allows you to feed entire codebases, long documents, or extended conversations into a single API call. The output limit is 4,096 tokens by default (extendable to 16,384 in some tiers).

OpenAI charges per token — both input (prompt) tokens and output (completion) tokens count toward your bill. A longer prompt consumes more input tokens, which directly increases cost. Understanding token counts before making API calls helps you optimize prompts, stay within context limits, and control spending. For example, GPT-4o costs $5 per 1M input tokens as of 2024.

No. All token counting happens entirely in your browser using JavaScript. Your text never leaves your device. This makes it safe to paste sensitive content like API keys, private documents, or proprietary code when estimating token counts.