Cost Per Impression Formula & Calculating Impressions from CPM

Understanding the underlying math of your digital advertising campaigns is crucial for optimizing your budget. While ad platforms provide automated reporting, knowing the manual math allows marketers to forecast outcomes and verify platform data.

The Cost Per Impression Formula Explained

The cost per impression formula is the foundation of all CPM (Cost Per Mille) advertising. It calculates the exact amount you pay for a single user to view your ad. The formula is simple: divide your total advertising cost by the total number of impressions generated.

• Formula: Total Cost ÷ Total Impressions = Cost Per Impression (CPI)
• Example: If you spend $500 on a Google Display campaign that generates 100,000 views, your CPI is $0.005. (To find your standard CPM, you simply multiply that number by 1,000, resulting in a $5.00 CPM).

The CPM Formula for Impressions

Often, marketers know their budget and their target CPM, but they need to forecast their total reach. When calculating impressions from cpm, you reverse the standard formula. You divide your total budget by the CPM, and then multiply by 1,000.

• The CPM formula for impressions: (Total Budget ÷ Target CPM) × 1,000 = Total Impressions
• Example: If you have a $2,000 budget for a YouTube ad campaign and the average CPM is $8.00, your calculation is ($2,000 ÷ $8.00) × 1,000. This campaign will yield an estimated 250,000 impressions.

Automate Your Campaign Math

Memorizing formulas is helpful, but calculating them across dozens of ad groups is time-consuming. To instantly switch between these formulas without manual math, use our free Cost Per Impression Calculator. Simply plug in your known variables, and the tool will instantly solve for your missing metrics.