Master the CPM formula in all 3 variants. Use our free CPM formula calculator, get the Excel formula, and see real examples — all in one place.
The CPM formula has three forms depending on which variable you need to solve. Know any two values — and the CPM formula gives you the third.
Use when you know your total spend and total impressions. The standard CPM formula — tells you the rate per 1,000 impressions.
Use when you know your CPM rate and target impressions. Calculates the total budget needed for your campaign.
Use when you have a fixed budget and a known CPM rate. Estimates your total reach from a given spend.
Understanding why the CPM formula works — not just how — gives you a real edge in planning campaigns and evaluating ad revenue.
The CPM formula — CPM = (Total Cost / Total Impressions) × 1,000 — is the foundation of impression-based advertising. "CPM" stands for Cost Per Mille, where "mille" is Latin for thousand. The ×1,000 in the formula normalizes cost to a per-thousand basis, making it easy to compare campaigns of any size.
Individual ad impressions cost fractions of a cent — too small to be practical. The CPM formula multiplies by 1,000 to express cost in a meaningful unit. A CPM of $5.00 means you pay $5 per 1,000 impressions, or $0.005 per single impression. This makes the CPM formula universally useful across campaigns of any scale.
When planning a campaign, you often know your CPM rate and target reach. The rearranged CPM formula gives you the required budget: Cost = (CPM × Impressions) ÷ 1,000. Example: targeting 5,000,000 impressions at a $4 CPM requires a $20,000 budget.
With a fixed budget and a known CPM, the impressions variant of the CPM formula predicts your reach: Impressions = (Cost / CPM) × 1,000. A $500 budget at $2.50 CPM delivers 200,000 impressions.
The eCPM (Effective CPM) formula is identical — eCPM = (Total Revenue / Total Impressions) × 1,000 — but applies from the publisher's perspective across any ad pricing model (CPC, CPA, CPV). The CPM formula and eCPM formula use the same math; the difference is whether you're the buyer or the seller.
The CPM formula measures cost efficiency — not campaign effectiveness. A low CPM doesn't guarantee results. Always combine the CPM formula output with CTR (click-through rate), conversion rate, and ROAS (return on ad spend) for a complete picture of campaign performance.
Apply the CPM formula directly in Excel or Google Sheets. Here are the exact formulas — ready to copy into your spreadsheet.
Assuming: A1=Label, B1=Value. Cost in B2, Impressions in B3.
Set up your spreadsheet with these columns and formulas:
Format cells correctly: Format Cost and CPM columns as Currency ($ symbol). Format Impressions as Number with comma separators. The CPM formula result should be formatted as Currency with 2 decimal places.
Avoid division by zero: Wrap the CPM formula in Excel with an IFERROR function: =IFERROR((B2/C2)*1000, "—"). This prevents #DIV/0! errors when impressions are empty.
Build a campaign comparison table: Put each campaign on a new row. Use the CPM formula in the D column for all rows. Add conditional formatting to highlight campaigns above or below your target CPM threshold.
Google Sheets: The CPM formula works identically in Google Sheets — same syntax, same logic. No adjustments needed when copying between Excel and Sheets.
Forgetting to multiply by 1,000: The most common CPM formula error. =(B2/C2) gives cost per impression, not CPM. Always include *1000 at the end.
Wrong units for impressions: Enter impressions as the full number (200000), not in thousands (200). The CPM formula already handles the per-thousand conversion.
Use our CPM formula calculator above to verify your Excel results — both should always match exactly.
Three steps to apply the CPM formula correctly — whether manually, in Excel, or with our CPM formula calculator.
The CPM formula needs exactly two inputs to solve for the third. Decide: do you know Cost + Impressions (solve for CPM), CPM + Impressions (solve for Cost), or Cost + CPM (solve for Impressions)?
Use CPM = (Cost ÷ Impressions) × 1,000 for rate calculation. Use Cost = (CPM × Impressions) ÷ 1,000 for budget planning. Use Impressions = (Cost ÷ CPM) × 1,000 for reach estimation.
Apply the CPM formula manually, in Excel, or use the CPM formula calculator above for instant results. Compare your CPM against industry benchmarks: $2–5 display, $2–10 YouTube, $15–50 finance niche.
Everything you need to know about the CPM formula, CPM formula calculator, and CPM formula in Excel.