Prompt Cost Calculator
Calculate and compare API costs for GPT-4, Claude 3, Gemini and other LLMs. Enter input/output tokens to estimate costs, compare models, and project monthly expenses.
GPT-4o (OpenAI)
Input: $2.50/1M • Output: $10.00/1M • Flagship multimodal model
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Calculate AI API Costs Instantly
Large language model APIs charge per token, making cost estimation essential for budgeting. Our calculator computes costs for GPT-4, Claude 3, Gemini, and other models, helping you compare pricing and optimize your AI spending.
How LLM API Pricing Works
AI providers charge separately for input tokens (your prompts) and output tokens (model responses). Input tokens are typically cheaper than output tokens. Costs are quoted per million tokens, so a 1,000-token prompt with GPT-4o costs about $0.0025 at current rates.
Cost Calculation Formula
Total Cost = (Input Tokens ÷ 1M × Input Rate) + (Output Tokens ÷ 1M × Output Rate)Why Calculate Prompt Costs?
Budget Planning
Estimate monthly API expenses before scaling your application. A chatbot handling 10,000 conversations/day can cost hundreds to thousands of dollars monthly.
Model Selection
Compare costs across providers. GPT-4o Mini is 17x cheaper than GPT-4o, while Claude 3 Haiku is 60x cheaper than Opus. Choose the right model for your quality/cost tradeoff.
Optimize Prompts
Shorter prompts cost less. System prompts that repeat with every request add up quickly—a 500-token system prompt costs $1.25 per 1,000 requests with GPT-4o.
Prevent Surprises
API costs can spike unexpectedly. Understanding your baseline costs helps set usage alerts and prevent budget overruns.
How to Use This Calculator
Frequently Asked Questions
Output tokens require the model to generate new content through an expensive autoregressive process, computing probabilities for each token sequentially. Input tokens are processed in parallel and only require encoding, not generation.