Resource
Estimate Token Usage Before You Run It
Know how many tokens a job will consume before you send it — input plus an assumed response, costed per call and at scale.
Count Tokens Before Sending to the API
A quick pre-flight check: count a system prompt's tokens and cost before it ships, so the bill and the size hold no surprises.
Overview
A system prompt rides along on every single request, so its token count is paid over and over. This loads a realistic support-agent system prompt and counts it as a pre-send check — the size and cost you commit to with each call. Counting before sending is the cheap habit that prevents the expensive surprise; this is the fast, honest read you run before the prompt goes live. For whether the whole conversation will still fit the window, hand off to the Context Window Estimator.
How to use this resource
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Paste before you ship
Check the prompt's size and cost before it goes live.
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Note the recurring cost
A system prompt is paid on every single request.
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Hand off for fit
For whole-conversation fit, use the Context Window Estimator.
Why This Works
- Counting before sending is a cheap habit that avoids expensive surprises
- System prompts are paid on every call — their count compounds
- A fast pre-flight read fits naturally before an API request
Best for
- Pre-flight checks before an API call
- Sizing a system prompt paid on every request
- Catching cost surprises before they ship
Not for
- Whole-conversation fit — use the Context Window Estimator
- Editing the prompt for clarity — use the Prompt Cleaner
FAQ
How much does a system prompt cost per API call?
The COST ESTIMATE block turns the size into money for the model shown. This support-agent prompt reports 'Combined per call: $0.0628–$0.0635' and 'Per 1,000 calls: $62.82–$63.45' on Claude Opus, so the recurring cost of a prompt paid on every request is visible before you ship. Treat these as estimates — verify provider rates before you rely on a number.
Is the token count from this pre-flight check exact for billing?
It is not — the estimate is a range, not tokenizer output. This report reads 'Estimated tokens: ~209 (range 188–230)' and the ESTIMATION NOTES call these character-based estimates, not exact counts. Providers meter with their own tokenizers and change rates, so use this to catch surprises before sending, then confirm the real bill against your provider's numbers.
Will this tell me if my whole conversation fits the context window?
It sizes and prices one prompt, not the full window — hand that off to the Context Window Estimator. The MODEL NOTES line spells it out: the per-model figures are 'a count, not a fit check'. This pre-flight read tells you what one call to a live system prompt estimates in cost, not whether an accumulating conversation will still fit.
More resources from Token Counter
Resource
Token Counter for AI Prompts
Paste a prompt, get an honest token estimate — a range, not a fake-precise number — plus the cost across GPT, Claude, and Gemini.
Resource
Calculate AI API Cost for a Prompt
Turn a prompt into a dollar figure: input cost, output cost, combined per call, and the number that actually matters — cost per 1,000 calls.
Resources that pair well
Resource
Estimate Token Budget — Plan Before You Paste
Token budget planning for real workloads: how much of the window a transcript actually consumes, what is left for the answer, and how much headroom remains.
Resource
Message Too Long — the Fix That Doesn't Butcher Content
The "message too long" error has a structural fix: split at paragraph boundaries into sequenced chunks with wait rules, instead of pasting fragments and hoping.
Resource
Prompt Cleanup Examples (Before & After)
A set of before-and-after examples showing exactly what prompt cleanup removes — and what it deliberately leaves alone.
Related tools
Tool
Token Counter
Estimate how many tokens a prompt is and what it costs — honest ranges across GPT, Claude, and Gemini, with per-call and per-1,000-call pricing.