What does text cost?
How these numbers are made
Tokens are the chunks a model actually reads — about three-quarters of an English word each, so 100 words is roughly 130–140 tokens.
OpenAI rows are exact. Your text is encoded in your browser by
the gpt-tokenizer library using o200k_base, the same
encoding OpenAI’s models use. Same input, same count, every time.
Claude rows are estimates. Anthropic doesn’t publish its tokenizer, so there’s nothing exact to run. I multiply the o200k count by 1.15 and mark it “est.” — read ±20% into it. Where this site has real Claude numbers — Arena races and Guess reveals — they come from Anthropic’s own usage reports, and those are exact.
The math on every line: tokens × rate ÷ 1,000,000 = the line’s cost, rounded to six decimals at display — recompute any line by hand. Rates per million tokens (MTok), as listed by OpenAI and Anthropic, verified 2026-07-09: GPT-4.1 nano $0.10 in / $0.40 out · GPT-5.4 nano $0.20 in / $1.25 out · Claude Haiku 4.5 $1.00 in / $5.00 out · Claude Sonnet 5 $2.00 in / $10.00 out.
The receipt prices sending your text, so lines use the input rate; what a reply would cost depends on its length (output rates above).
Nothing you type leaves the page — the counting runs in your browser. The headline’s own token boundaries are computed once, when the site is built. Your text is tokenized live, on your device.