AI & LLM
Token, cost & context tools for LLMs
Claude Token Counter — Estimate Tokens for Anthropic Models
Anthropic does not publish Claude's tokenizer, so this counter uses a calibrated estimate (approximately 1 token per 3.5 characters) derived from Anthropic's own guidance and community benchmarks. For the reference sentence "The quick brown fox jumps over the lazy dog.", Claude Opus 4.8 is estimated at 13 tokens ≈ 10 words. Claude Opus 4.8 has a 1M-token context window — one of the largest available — at $5.00/M input tokens. Paste your system prompt or document to check whether it fits within Claude's context limit.
Sample: "The quick brown fox jumps over the lazy dog."
- Estimated tokens (Claude, chars ÷ 3.5): 13
- Word equivalent (tokens × 0.75): ≈ 10 words
- Claude Opus 4.8 context window: 1,000,000 tokens
- Claude Opus 4.8 max output: 128,000 tokens
- Tokenizer accuracy: ESTIMATED (Anthropic tokenizer is proprietary) — as of 2026-07-03
Frequently asked questions
How accurate is the Claude token estimate in this calculator?
Anthropic does not release Claude's tokenizer, so the count is an estimate based on approximately 3.5 characters per token for English text. This is typically within ±10% of the actual tokenizer output for standard English prose. Code, JSON, and non-English text may differ more. For tight context-limit decisions (e.g. prompts close to the 1M ceiling), add a 10–15% safety margin to the estimate.
How many tokens can Claude Opus 4.8 handle?
Claude Opus 4.8 has a 1,000,000-token (1M) context window. At 0.75 words per token, that is roughly 750,000 words — equivalent to 2–3 full-length novels. The maximum output per response is 128,000 tokens. Input pricing is $5.00/M tokens; with prompt caching, re-used prefixes cost $0.50/M tokens.