Claude Opus 5 (Fast mode) Token Calculator
The Claude Opus 5 (Fast mode) token calculator below counts Claude Opus 5 (Fast mode) tokens and prices them at Anthropic's published rates — $10.00 per 1M input tokens and $50.00 per 1M output tokens, last verified 2 October 2026. Anthropic does not publish its tokenizer, so the count is a calibrated estimate — stated plainly on every table here rather than dressed up as exact. Use it to budget and to compare Claude Opus 5 (Fast mode) against other models.
Open the full Claude Opus 5 (Fast mode) counter with the whole pricing table →
Claude Opus 5 (Fast mode) token cost at a glance
| Volume | Approx. size | Input cost | Output cost |
|---|---|---|---|
| 1K tokens | ≈ 769 words | $0.01 | $0.05 |
| 10K tokens | ≈ 7,692 words | $0.1 | $0.5 |
| 100K tokens | ≈ 76,923 words | $1.00 | $5.00 |
| 1M tokens | ≈ 769,230 words | $10.00 | $50.00 |
Figures are list prices per 1M tokens, verified 2 October 2026. Enterprise contracts and volume tiers differ — edit the rates in the calculator if your deal is not list.
How accurate is the Claude Opus 5 (Fast mode) count?
Anthropic does not publish a public tokenizer, so this page reports an estimate — accurate to roughly 5–10% on English text and widening on code or mixed Chinese-English prompts. Treat it as a budgeting number, not an invoice number. If you need invoice-grade counts, count with the exact OpenAI tokenizer on the main calculator and read the gap as your margin of safety.
## What fits in the Claude Opus 5 (Fast mode) context window Claude Opus 5 (Fast mode) accepts **1M tokens**. At roughly 1.3 tokens per English word that is about **769,230 words**, or roughly **3,600,000 characters** of prose. Code and CJK text consume the budget faster: a source file or a Chinese document of the same visible length can run 30–60% more tokens, so leave headroom rather than budgeting to the exact ceiling.Claude Opus 5 (Fast mode) pricing against the rest of Anthropic
| Model | Tokenizer | Context | Input / 1M | Output / 1M |
|---|---|---|---|---|
| Claude Opus 5 (Fast mode) | estimate | 1M | $10.00 | $50.00 |
| Claude Opus 5.5 | estimate | 1M | $4.00 | $20.00 |
| Claude Opus 5 | estimate | 200K | $5.00 | $25.00 |
| Claude Sonnet 5 | estimate | 1M | $2.00 | $10.00 |
| Claude Haiku 4.5 | estimate | 200K | $1.00 | $5.00 |
| Claude Fable 5 | estimate | 1M | $10.00 | $50.00 |
| Claude Opus 4.6 | estimate | 1M | $5.00 | $25.00 |
| Claude Sonnet 4.6 | estimate | 1M | $3.00 | $15.00 |
| Claude Opus 4.7 | estimate | 1M | $5.00 | $25.00 |
| Claude Opus 4.8 | estimate | 1M | $5.00 | $25.00 |
| Claude Fable 5.1 | estimate | 1M | $10.00 | $50.00 |
| Claude Sonnet 5.5 | estimate | 1M | $2.00 | $10.00 |
| Claude Mythos 5 | estimate | 1M | $11.00 | $55.00 |
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Claude Opus 5 (Fast mode) token FAQs
How many tokens is a word in Claude Opus 5 (Fast mode)?
About 1.3 tokens per English word for Claude Opus 5 (Fast mode) — roughly 3.6 characters per token. Code and CJK text tokenize denser, so a 1M tokens window holds fewer words than a prose estimate suggests.
What does Claude Opus 5 (Fast mode) cost per 1M tokens?
Claude Opus 5 (Fast mode) is listed at $10.00 per 1M input tokens and $50.00 per 1M output tokens as of 2 October 2026.
What is the Claude Opus 5 (Fast mode) context window?
Claude Opus 5 (Fast mode) accepts up to 1M tokens of input.
Is the Claude Opus 5 (Fast mode) token count on this page exact?
No. Anthropic does not expose its tokenizer, so this is a calibrated estimate at 5–10% accuracy.
Does this Claude Opus 5 (Fast mode) calculator upload my text?
No. Tokenization runs entirely in your browser over JavaScript. Your text is never sent to any server, which is why the tool works with client code, unreleased prompts and internal data.