Cost = total_tokens × price_per_million / 1,000,000

def estimate_monthly_cost(
    requests_per_day: int,
    avg_tokens_per_request: int,
    price_per_million: float
) -> float:
    daily_tokens = requests_per_day * avg_tokens_per_request
    monthly_tokens = daily_tokens * 30
    cost = monthly_tokens * price_per_million / 1_000_000
    return cost

# Example: 1000 requests/day, 500 tokens each, $0.10/M
cost = estimate_monthly_cost(1000, 500, 0.10)
print(f"Monthly cost: ${cost:.2f}")  # $1.50