Toolivaro

Free AI Token Counter

Estimate tokens and API cost for any prompt across GPT-4o, Claude Sonnet 4, and other models — fully local.

Processed locally in your browser

Optional — used to estimate output-token cost.

How is the result calculated?

A 200-word system prompt on GPT-4o

A system prompt of 1,000 characters is estimated at 250 tokens on GPT-4o (4 characters per token). At $2.50 per million input tokens the input costs about $0.0006; adding a requested 200-word answer (≈ 267 output tokens at $10 per million) brings the total to about $0.0033 per call.

Input Value
prompt 1,000-character system prompt
model GPT-4o
outputWords 200
Result ≈ 250 input tokens · ≈ 267 output tokens · ≈ $0.0033 per call

What is the formula and its assumptions?

Token estimate

tokens ≈ ceil(characters ÷ 4)

Symbol Meaning
characters length of the prompt text (code points)
4 vendor-documented approximation: ~4 characters per token (English)

An estimate, not the exact tokenizer output. Exact counts require each model’s BPE vocabulary, which cannot ship in a static page.

Cost estimate

cost = (inputTokens ÷ 1,000,000 × inputPrice) + (outputTokens ÷ 1,000,000 × outputPrice)

Symbol Meaning
inputPrice list price per million input tokens (as of 2026-08-05)
outputPrice list price per million output tokens (as of 2026-08-05)

Output tokens are estimated at ~0.75 words per token when you provide an expected output length.

What are the most common mistakes?

  • Treating the estimate as the exact billing count — vendor tokenizers are authoritative for billing.
  • Assuming four characters per token for non-English text — the heuristic is calibrated for English.
  • Forgetting that output tokens usually cost more per token than input tokens.
  • Pasting sensitive proprietary code into an online tokenizer — this tool keeps everything local.

What are the assumptions and limitations?

  • The estimate is heuristic (characters ÷ 4), not the model’s exact tokenizer output; accuracy drops for non-English text, dense punctuation, and code.
  • Prices are public list rates as of 2026-08-05 and may change; always confirm at the vendor pricing page before committing spend.
  • Context windows and prices apply to the listed model names at the recorded date; a model update may change both.

Where do the numbers come from?

Last reviewed August 5, 2026 · Version 1.0.0 · Toolivaro does not guarantee external content.

Frequently asked questions

Why is the count an estimate instead of exact?

Exact token counts come from each model’s tokenizer, a BPE vocabulary that ships inside the model provider’s libraries — too large to embed in a static page. The documented ~4 characters-per-token heuristic is within a few percent for typical English prompts, which is accurate enough for cost and context planning.

Does the count match the OpenAI or Anthropic tokenizer pages?

Close, but not identical. The official tokenizers use the real vocabulary and are exact; this tool uses the documented heuristic so it can run entirely in your browser. For billing-critical counts, use the vendor tokenizer — the estimate here is for planning.

Why are prices dated?

Model pricing changes. The tool records the public list rates it was built against (2026-08-05) and shows that date with every result, so a later price change at the vendor is never silently baked into an estimate.

Found a mistake or have a correction? Report it — we review every correction.