LLM API Token Cost Calculator: Estimate Your Monthly AI Spend

Estimate your monthly and annual LLM API costs from request volume and average token counts, with built-in pricing for GPT, Claude, and Gemini models.

Mathematical Audit

LLM API Token Cost Formula

We multiply your daily request volume by an average month length to get monthly requests, then multiply by your average input and output token counts per request to get total monthly token volume. Each token total is divided by 1,000,000 and multiplied by the selected model's per-million-token price.

Monthly Requests = Requests per Day × 30.4
Total Input Tokens = Avg Input Tokens per Request × Monthly Requests
Total Output Tokens = Avg Output Tokens per Request × Monthly Requests
Input Cost = (Total Input Tokens ÷ 1,000,000) × Input Price per 1M Tokens
Output Cost = (Total Output Tokens ÷ 1,000,000) × Output Price per 1M Tokens
Total Monthly Cost = Input Cost + Output Cost
Total Annual Cost = Total Monthly Cost × 12

Pricing reflects standard, non-cached, non-batch API rates at the time of writing. Prompt caching can cut input costs by up to 90% on repeated context, and Batch APIs offer roughly 50% off both input and output tokens for asynchronous workloads — neither discount is applied by default here. Always confirm current rates on each provider's official pricing page before budgeting.

Operational Guide

How to Use the LLM API Token Cost Calculator

1

Select your model

Choose from popular models like GPT-4o, GPT-5.2, Claude Sonnet 4.6, Claude Haiku 4.5, Claude Opus 4.8, or Gemini 2.5 Flash/Pro — or pick Custom to enter your own per-token pricing.

2

Enter average tokens per request

Estimate how many input (prompt) tokens and output (completion) tokens a typical request uses. As a rule of thumb, 1,000 tokens is roughly 750 words.

3

Enter your daily request volume

Enter how many API calls your app makes per day on average — this gets scaled to a 30.4-day month.

4

Click Calculate

View your projected monthly and annual cost, broken down by input vs. output token spend.

Real-World Scenario Example

"A chatbot app makes 2,000 requests per day, each using around 1,200 input tokens and 600 output tokens, on Claude Sonnet 4.6 ($3/$15 per 1M tokens)."

Inputs

model:claudeSonnet
avgInputTokensPerRequest:1200
avgOutputTokensPerRequest:600
requestsPerDay:2000

Result

Total monthly cost is roughly $776 (about $221 for input tokens and $555 for output tokens), or about $9,318/year.

Important Disclaimer

LLM API pricing changes frequently as providers release new models and adjust rates. The per-model prices used in this calculator reflect publicly listed standard rates at the time of writing and are for educational budgeting purposes only — verify current pricing on each provider's official pricing page before making purchasing decisions.

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Sources & References

Claude API Pricing — Anthropic

https://platform.claude.com/docs/en/about-claude/pricing

Gemini API Pricing — Google AI for Developers

https://ai.google.dev/gemini-api/docs/pricing