Should retries count as requests?

Yes. Include billable retries in the monthly request estimate or create a separate higher-volume scenario.

What belongs in fixed monthly costs?

Only costs you want in the same budget, such as observability, hosting, storage, or subscriptions; avoid double counting.

Why is cost per request undefined at zero requests?

Division by zero has no meaningful per-request result, even when fixed costs remain.

Is this the same as pricing one prompt?

No. Use the Token Cost Calculator for one known workload; use this page for recurring request-volume planning.

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Monthly LLM API Cost Calculator

Turn request volume and average token usage into a transparent recurring AI budget.

Monthly request scaling

Separate input and output usage

Fixed platform cost allowance

Projects recurring LLM API usage by multiplying monthly requests by average input and output tokens, then adds entered fixed monthly costs.

Limitation: This is a deterministic planning estimate, not an invoice forecast.

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Free Calculators HubLLM API Cost Calculator

CurrencyRequests per monthExpected billable API calls in the budget period.Average input tokens per requestObserved or planned average across prompts, system messages, tools, and context.Average output tokens per requestObserved or planned mean billable generated tokens.Input rate per 1 million tokensEnter the current effective input rate for this workload.Output rate per 1 million tokensEnter the current effective output rate.Fixed monthly costsHosting, observability, vector storage, subscriptions, or other entered fixed costs.

Understanding Monthly LLM API Cost Calculator

How to Plan an LLM API Budget

Use production telemetry when available; otherwise document why your planning averages are reasonable.

Choose the reporting currency.

Use percentiles for risk planning

An average is useful for a base case, but a separate high-usage scenario can expose context-window growth, retries, and traffic spikes.

What the Monthly API Model Calculates

The model scales average tokens across a recurring request count. Unlike the Token Cost Calculator, it is a period budget rather than a price for one already-defined workload.

Recurring LLM Budget Examples

Production monthly base case

Monthly traffic, averages, rates, and fixed costs

requestsPerMonth:100000

averageInputTokensPerRequest:1500

averageOutputTokensPerRequest:500

inputRatePerMillion:2

outputRatePerMillion:8

fixedMonthlyCosts:50

Projected monthly cost

$750.00 per month

Input usage costs 300, output usage costs 400, and fixed costs add 50.

No requests during setup

Monthly traffic, averages, rates, and fixed costs

requestsPerMonth:0

fixedMonthlyCosts:25

Projected monthly cost

$25.00 per month

Usage is zero while entered fixed infrastructure costs remain.

Separate base and stress cases

Repeat the calculation with higher request and token assumptions instead of treating one average as a guarantee.

Frequently Asked Questions

No. Rates change and may depend on account terms, so you enter the rates that apply.

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Monthly LLM API Budget Formulas

The workload average is expanded into period token totals before per-million prices are applied.

Formula

monthly tokens = requests per month × average tokens per request

Monthly token volumes

monthly tokens = requests per month × average tokens per request

Monthly token charges

token charge = monthly tokens ÷ 1,000,000 × entered rate

Total monthly budget

total = input charge + output charge + fixed monthly costs

Scientific Background

Official provider pricing documentation commonly distinguishes input and output token categories. The engine uses that unit convention but deliberately requires the user to enter current rates.

Sources & review

LLM API Cost Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.

Last reviewed

July 22, 2026

Reference
platform.openai.com
https://platform.openai.com/docs/pricing
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