Context Overflow Calculator
Determine whether your prompt and history exceed a model's maximum context window.
Inputs
Overflow Tokens
616
Context Utilization
103.8%
Total Tokens Needed
17,000
Step by step
Total tokens needed
3000 + 12000 + 2000
= 17000
Overflow
17000 − 16384
= 616 tokens over
How it works
Context overflow occurs when the sum of prompt tokens, conversation history, and reserved completion tokens exceeds the model's maximum context window. When overflow happens, you must truncate history, summarize context, or switch to a model with a larger context window.
Formula
Overflow Check
overflow = max(prompt + history + reserved - max_context, 0)
- max_context
- Model's maximum context window in tokens
Frequently Asked Questions
What happens when context overflows?
Most APIs return an error. Some frameworks silently truncate the oldest messages. Either way, important context is lost, potentially degrading response quality.
How can I avoid overflow?
Implement sliding window history, summarize old messages, use RAG to retrieve only relevant context, or upgrade to a model with a larger context window.