What is a token in AI language models?

A token is roughly 4 characters or 3/4 of a word in English. ChatGPT is amazing is about 5 tokens. AI models process and charge by token, not by word or character.

What are the context window limits?

GPT-4o: 128K tokens. Claude 3.5 Sonnet: 200K tokens. Gemini 1.5 Pro: 1 million tokens. GPT-3.5: 16K tokens. Going over the limit causes the conversation to be truncated.

How are API costs calculated?

Most APIs charge separately for input tokens (your prompt) and output tokens (the AI response). GPT-4o is approximately $5 per million input tokens and $15 per million output tokens.

Why do token counts differ between models?

Different models use different tokenizers. GPT models use BPE tokenizers via tiktoken. Claude uses a similar approach. The count can vary by 5 to 15% between models for the same text.

AI Token Counter — GPT-4, Claude, Gemini Token & Cost Estimator | Free Edu & .COM Temporary Mails

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AI Token & Character Counter

Count tokens, characters, words, and lines for GPT-4, Claude, Gemini, and Llama. Estimate API costs before sending prompts. Free, instant, private.

AI Model:

Text Input

Tokens

Characters

Words

Lines

💰 API Cost Estimate (GPT-4o)

Input cost:$0.000000

Per 1K tokens:$0.005

Context used:0%

📊 Context Window: 128K

Your text uses 0% of the available context window.

Remaining: 128,000 tokens available

AI Model Token Pricing Comparison (2025)

Model	Context Window	Input (per 1M tokens)	Output (per 1M tokens)
GPT-4o	128K	$5.00	$15.00
GPT-4	128K	$30.00	$60.00
GPT-3.5 Turbo	16K	$0.50	$1.50
Claude 3 Opus	200K	$15.00	$75.00
Claude 3 Sonnet	200K	$3.00	$15.00
Gemini 1.5 Pro	1M	$1.25	$5.00
Llama 3.1 70B	128K	$0.59	$0.79

AI Token & Character Counter

AI Model Token Pricing Comparison (2025)

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