AI API Monthly Budget Calculator
Turn daily request volume and average prompt and reply length into a monthly AI API bill, cost per request, per day and per year, at current GPT, Claude and Gemini prices.
Last updated: October 2026
Monthly API cost
$105.00
Formula below · 3 sources (developers.openai.com, platform.claude.com, ai.google.dev) · Updated Oct 2026
Compare with similar
About this calculator
A monthly API budget is the per-request cost times the number of requests:
monthly cost = requests per day × days × (input tokens × input price + output tokens × output price) ÷ 1,000,000
Use averages measured from real traffic where you can: the usage block in every API response gives exact input and output tokens. Chat applications resend the conversation history with each turn, so the average input grows with conversation length.
Prices are standard list prices as of October 2026. GPT-6 requests with prompts over 272,000 tokens pay 2× input and 1.5× output; Claude Haiku 5.5 prompts over 100,000 tokens pay $0.50 / $2.50. Budgets usually add a margin for retries, traffic growth and the occasional very long request; prompt caching and the Batch API can reduce the total.
How to use
Pick the model, then enter requests per day, average input and output tokens per request, and the days the workload runs each month. Example (the defaults): GPT-6.1 Sol ($2 / $10), 500 requests a day of 1,500 input and 400 output tokens, 30 days. Per request: (1,500 × 2 + 400 × 10) ÷ 1M = $0.007. Monthly: 500 × 30 × $0.007 = $105.00, or $3.50 a day and $1,260 a year. That is 28.5 million tokens a month. Example 2: the same traffic on Claude Haiku 5.5 ($0.10 / $0.50): 15,000 × (1,500 × 0.10 + 400 × 0.50) ÷ 1M = $5.25 a month. Example 3: 22 working days instead of 30 on GPT-6.1 Sol: 500 × 22 × $0.007 = $77.00.
Frequently asked questions
How do I set a spending limit on the API?
OpenAI, Anthropic and Google let you set budgets or spend limits and alerts per organisation or project in their consoles. Set the limit a little above this estimate, and alerts at about 50% and 80% of it, so a bug that loops requests cannot run up an unlimited bill.
Why is my real bill higher than the estimate?
Usually because real requests are longer than assumed: chat history resent on every turn, retrieved documents, tool definitions, retries after errors, and reasoning tokens billed as output. Compare the token counts in your usage dashboard with the averages entered here.
How can I lower a monthly AI API bill?
Route simple requests to a small model, cap the output length, cache long repeated prefixes (system prompts, documents), and send work that can wait to the Batch API, which all three providers discount by 50%.
How current are the prices?
They are the standard list prices on the OpenAI, Anthropic and Google pricing pages as of October 2026 (checked 17 October 2026), before taxes, volume discounts or regional surcharges. Google has announced increases for Gemini 4 Argon (from December 1, 2026) and Gemini 3.8 Flash (from January 1, 2027); both prices are in the list. Providers change prices often, so confirm on the official pricing page before you commit a budget.
Related calculators
Sources & references
Think a result is wrong? Report a problem with this calculator.