The total cost or budget of a campaign is calculated by multiplying Cost per Acquisition (CPA) by conversions, Cost per Click (CPC) by clicks, or dividing CPM by 1000 and multiplying it by impressions. This is the formula to calculate the cost of a campaign:
Cost=CPA x Conversions  Cost=CPC x Clicks 

Use our PPC Calculator to automatically calculate budget and other Google Adwords metrics.