Claude & Anthropic Token Counting (Approximate)
Last updated: July 2026
Size Claude prompts in the browser with labeled estimates—why Anthropic has no static tiktoken twin, how to plan context, and when to verify on the API.
Searches for claude token counter, anthropic token counting, and token counter claude usually mean: size this paste before you stuff a long spec into Claude. Anthropic does not ship a public tiktoken-style twin for static sites — so our Claude modes are labeled approximate on purpose.
What Anthropic meters
Claude APIs and products work in tokens (and their own context limits). Exact splits belong to Anthropic’s APIs and docs. A browser estimate is for planning: how heavy is this paste, and will it burn the window fast.
Why “approximate” stays visible
Without a browser-identical tokenizer, we use documented approximation rules and badge the result. See tiktoken vs approximate and methodology. Do not treat the number as an invoice.
Recommended workflow
Open the token counter, pick a Claude / Anthropic-oriented mode, paste system + tools + user text. Near the limit, use the context window calculator for fill % and leave room for the reply.
Multi-turn and tools
Prior turns, tool results, and JSON add up. Count chunks separately or paste the combined payload you will actually send. Critical paths still verify on the Anthropic API.