ToolPuma Logo

Prompt Length Checker

Verify a prompt fits a model's context window.

Context usage0 / 128k (0%)
0
Prompt tokens
127,000
Max input w/ output
Too long
Status

What Is a Prompt Length Checker?

The Prompt Length Checker verifies that a prompt fits comfortably within a model's context window. It compares the prompt's token count against the window, reserving space for output, and flags prompts that are too long or close to the limit.

How to Use This Prompt Length Checker

  1. 1
    Pick a modelSelect the target model.
  2. 2
    Paste the promptThe token count is estimated automatically.
  3. 3
    Set output reserveEnter the tokens you expect for the reply.
  4. 4
    Read the verdictSee whether the prompt fits and how much room remains.

Frequently Asked Questions

The API typically returns an error, or the model silently truncates the input. Checking in advance avoids failed calls.
Reserve whatever you expect the model to generate. If in doubt, use the model's max output or a value you have observed in practice.
Yes. Trim redundant instructions, compress the history, or switch to a model with a larger context window using the comparison tool.

Related AI & LLM Tools Tools

AI Token Counter

Count the estimated tokens in any text or prompt.

LLM Token Cost Calculator

Estimate the cost of LLM token usage across models.

Multilingual Token Counter

Estimate tokens for text in any writing system.

Tokenizer Visualizer

See how text splits into approximate tokens.

Context Window Calculator

Check how much of a model's context window is used.

Prompt Cost Calculator

Estimate the token cost of a single prompt.

More AI & LLM Tools Tools

OpenAI Cost Calculator

Estimate OpenAI API costs for GPT models.

Claude Cost Calculator

Estimate Anthropic Claude API costs with caching.

Gemini Cost Calculator

Estimate Google Gemini API costs.

Token Efficiency Calculator

Measure how many tokens a rewritten prompt saves.

RAG Chunking Calculator

Plan chunk size and overlap for RAG pipelines.

Embedding Cost Calculator

Estimate embedding API costs for your corpus.