calx, calcis
A small stone.
The Latin genitive of calx.
Limestone. Chalk. Pebble.
The thing you hold in your hand
before you count.
Rome, circa 100 BC
Before the transaction,
the stones.
Roman merchants counted with calculi, small pebbles, before committing to a deal.
The cost was known first.
Always first.
TOKENS COUNTED
1,247
input tokens · before you send
COST BEFORE THE CALL
$0.0084 estimated
The same root
One stone.
All of mathematics.
From calcis came calculus, the pebble used for reckoning.
From calculus came calculate. From calculate came every spreadsheet, every budget, every number that ever mattered.
calcis → calculus → calculate → cost
What changed
The bill arrives
after the call.
LLM APIs charge per token. The cost appears on your invoice, not before the request fires.
Nobody lays out the stones first.
Until now.
MONTHLY INVOICE
$847.23
OpenAI API · billed after the fact
No warning. No preview.What [calcis] does
Paste a prompt.
See what it costs.
Exact token counts using each provider's own tokeniser.
Output prediction before generation.
Cost across 25+ models before you send a single request.
SAME PROMPT · 1K IN / 500 OUT
| GPT-5 nano | OpenAI | $0.0003 |
| Gemini 2.5 Flash | $0.0016 | |
| GPT-4o | OpenAI | $0.0075 |
| Claude Sonnet 4.6 | Anthropic | $0.0105 |
4 of 24 supported models shown.
calcis, from calx
The count,
before the call.
Know what every API call costs before you make it. Free to start.