How this Claude Token Calculator works
How Claude counts tokens
Claude uses Anthropic's own tokenizer, so the same text often tokenizes to a slightly different count than GPT — don't assume a GPT estimate transfers exactly. Roughly three-and-a-half to four characters per token works for rough English planning, and Anthropic's token-counting endpoint gives exact figures. The system prompt and prior conversation are resent on every turn, so input grows as a session lengthens.
Choosing the right Claude model
The verified lineup includes Claude Fable 5.1 at the highest standard token price, Claude Opus 5.5 and Opus 4.7 for demanding reasoning and agentic work, Claude Sonnet 4.6 as the balanced production default, and Claude Haiku 4.5 for fast, inexpensive, high-volume tasks. Output is priced above input on each tier, so generation-heavy features lean on output cost — switch models in the calculator above to compare the same workload.
Prompt caching and what's excluded
Anthropic's distinctive lever is prompt caching: reusing a large, stable prefix such as a long system prompt or reference document sharply cuts the input cost of repeated calls. This calculator uses standard uncached pricing, so caching-heavy workloads cost less than shown. It also excludes the Batch API, long-context premiums, and tool use — verify the real numbers in the Anthropic console.