Free Developer Tool
LLM Prompt Cost Estimator
Paste your prompt and see exactly what each API call costs across every major LLM. Separate system and user prompts, set output length, and get prompt caching tips. 100% Browser-Based
System Prompt (optional)
User Message
Output & Volume
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Cost per API Call
Type or paste a prompt above to see per-call costs.
Prompt Caching Opportunity
Understanding Prompt Costs
How Prompt Costs Work
Every API call has two cost components: input tokens (your prompt) and output tokens (the model's response). Input tokens include both your system prompt and user message. Output tokens depend on the response length, which varies by task. Longer system prompts add up quickly at scale.
System Prompts & Cost
System prompts are sent with every API call. A 500-token system prompt across 10,000 daily requests means 5 million extra input tokens per day. Keeping system prompts concise is one of the easiest ways to reduce costs without sacrificing quality.
Prompt Caching
Providers like OpenAI, Anthropic, and Google offer prompt caching for system prompts and repeated prefixes. Cached input tokens are typically 50-90% cheaper. If your system prompt is a large portion of your input, caching can dramatically reduce costs.
100% Client-Side
All cost calculations happen entirely in your browser. Your prompts are never sent to any server. Pricing data is fetched from our API and updated regularly to reflect current API rates from each provider.
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