LLM Context Window Visualizer

About the LLM Context Window Visualizer

Visualizes how a context window is allocated across system prompt, conversation history, the new user message and the reserved response space.

How to use

Enter the token counts for each part and the total window, then click Calculate.

Worked example

Window 8192 = 300 system + 4000 history + 200 user + 1000 reserved → 2692 free.

How to use this calculator

1. Enter the token counts for system, history, and response.
2. Add the three values to find the total tokens used.
3. Compare the total to the model's context window limit to see how full it is.

The formula explained

• \(\text{system tokens}\) = Tokens used by the system prompt or instructions
• \(\text{history tokens}\) = Tokens used by prior messages in the conversation
• \(\text{response tokens}\) = Tokens reserved for or used by the assistant reply
• \(\text{total tokens used}\) = The combined number of tokens filling the context window

Step by step method

1. Start by identifying how many tokens are used by the system instructions.
2. Add the tokens from conversation history, including prior user and assistant messages.
3. Add the tokens needed for the response you want to generate.
4. Use the total to understand how much of the context window is occupied.

Worked example

Suppose a chat uses 120 system tokens, 1,850 history tokens, and 430 response tokens.

1. First, add the system and history tokens: \(120 + 1850 = 1970\).
2. Then add the response tokens: \(1970 + 430 = 2400\).
3. So the context window is filled by 2,400 tokens in total.

Tips and common mistakes

• Make sure you count system, history, and response separately before adding them.
• Do not confuse characters with tokens, since they are not the same thing.
• If the total is close to the limit, older history may need to be trimmed.
• Check whether the tool is showing reserved response tokens or actual generated tokens.

Frequently asked questions