AI Prompt Optimizer: Role, Context, Task and Format

Fill in role, context, task, constraints and output format to build a structured prompt and estimate its tokens.

Structuring an AI prompt in 5 blocks and estimating tokens

The tool assembles your prompt into five sections (role, context, task, constraints, output format), then estimates the token count at one token per 4 characters. The displayed cost multiplies those tokens by a fixed input price per model, for example $2.50 per million tokens for GPT-4o.

What the tool does

The five fields are placed into a template with headings (role and expertise, project context, main task, strict constraints, expected output format). The result is ready to copy. Everything runs in your browser: nothing is sent to an AI service.

Formulas

  • Estimated tokens = prompt character count ÷ 4, rounded up.
  • Input cost ($) = tokens ÷ 1,000 × the selected model's price per 1,000 tokens.

Prices coded in the tool, per million input tokens: Gemini Flash $0.10, Gemini 1.5 Pro $1.25, GPT-4o $2.50, Claude 3.5 Sonnet $3.00.

Example

A 1,200-character prompt gives 1,200 ÷ 4 = 300 tokens. Input cost: $0.00003 with Gemini Flash, $0.00038 with Gemini 1.5 Pro, $0.00075 with GPT-4o and $0.00090 with Claude 3.5 Sonnet.

Limits

  • The 4-characters-per-token rule comes from English; French, Spanish or German text often splits into more tokens. Each provider uses its own tokenizer.
  • Only input is priced: the model's answer (output tokens, which cost more) is not counted.
  • The block structure helps you write a complete request; it does not guarantee the quality of the answer.

Sources and dates: as of 14/10/2026, OpenAI's official price list still shows $2.50 per million input tokens for GPT-4o. Gemini 1.5 and Claude 3.5 Sonnet no longer appear on the Gemini API price list or on Anthropic's price list: the tool's prices for those models are historical and only give an order of magnitude (checked on 14/10/2026).

Frequently Asked Questions

How many tokens are in a 1,000-character prompt?

The tool uses one token per 4 characters, so 250 tokens for 1,000 characters. This approximation is calibrated on English; real tokenizers often produce a few more tokens for other languages.

What are the 5 parts of a good prompt?

The tool uses five: the role given to the AI, the project context, the main task, the constraints to respect and the expected output format. Separating them with headings keeps an instruction from getting lost in a continuous paragraph.

Does the displayed cost include the AI's answer?

No. The tool only prices input tokens, with a fixed rate per model ($2.50 per million for GPT-4o). Output tokens are billed separately and usually cost several times more.

Is my prompt sent to ChatGPT or Gemini?

No. The prompt is assembled and counted in your browser. You then paste it yourself into the AI tool of your choice.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.