Marketing and advertising rely on a wide range of formulas to evaluate media costs, campaign performance, customer acquisition, conversion, retention, and financial return. The AAMA Common Marketing Formulas reference brings together frequently used calculations in one place, with clear explanations of what each formula measures and how it should be interpreted.
This resource is designed for marketing and advertising professionals, agencies, brands, students, academics, analysts, and anyone who needs a practical reference for commonly used calculations. Formulas should always be applied with an understanding of the underlying data, assumptions, and business context because the same metric may be calculated differently depending on the organization or platform.
Advertising & Media Formulas
Cost per Mille
Cost per mille, or CPM, measures the cost of 1,000 advertising impressions. It is commonly used to compare the relative cost efficiency of media placements and campaigns focused on audience exposure.
Formula: CPM = Advertising Cost ÷ Impressions × 1,000
Example: A campaign spends $5,000 and generates 1,000,000 impressions. The CPM is $5.00.
Related AAMA Resource: CPM Calculator
Cost per Click
Cost per click, or CPC, measures the average advertising cost associated with each click generated by a campaign. It is commonly used in paid search, paid social, display advertising, and other digital channels.
Formula: CPC = Advertising Cost ÷ Clicks
Example: A campaign spends $2,000 and generates 4,000 clicks. The CPC is $0.50.
Related AAMA Resource: CPC Calculator
Click-Through Rate
Click-through rate, or CTR, measures the percentage of impressions that generate a click. It can help evaluate whether creative, targeting, messaging, or placement is generating interaction.
Formula: CTR = Clicks ÷ Impressions × 100
Example: An advertisement receives 2,500 clicks from 250,000 impressions. The CTR is 1%.
Related AAMA Resource: CTR Calculator
Cost per Acquisition
Cost per acquisition, or CPA, measures the average campaign cost required to generate a defined acquisition. An acquisition may represent a sale, registration, subscription, lead, application, or another completed action.
Formula: CPA = Campaign Cost ÷ Acquisitions
Example: A campaign spends $10,000 and generates 500 acquisitions. The CPA is $20.
Related AAMA Resource: CPA Calculator
Reach
Reach estimates the number of unique individuals exposed to a campaign when total impressions and average frequency are known.
Formula: Reach = Gross Impressions ÷ Frequency
Example: A campaign generates 1,200,000 gross impressions with an average frequency of 4. The estimated reach is 300,000 people.
Related AAMA Resource: Reach Calculator
Frequency
Frequency measures the average number of times each reached individual is exposed to a campaign.
Formula: Frequency = Gross Impressions ÷ Reach
Example: A campaign generates 900,000 impressions among 300,000 people. The average frequency is 3.
Related AAMA Resource: Frequency Calculator
Gross Impressions
Gross impressions represent the total number of advertising exposures generated by a campaign, including repeated exposure to the same individuals.
Formula: Gross Impressions = Reach × Frequency
Example: A campaign reaches 250,000 people with an average frequency of 4. The campaign generates 1,000,000 gross impressions.
Related AAMA Resource: Gross Impressions Calculator
Conversion & Campaign Performance Formulas
Conversion Rate
Conversion rate measures the percentage of users, visits, clicks, leads, or other opportunities that result in a defined conversion.
Formula: Conversion Rate = Conversions ÷ Total Opportunities × 100
Example: A landing page receives 10,000 visits and generates 500 completed registrations. The conversion rate is 5%.
Related AAMA Resource: Conversion Rate Calculator
Return on Ad Spend
Return on ad spend, or ROAS, compares revenue attributed to advertising with the amount spent on that advertising.
Formula: ROAS = Attributed Revenue ÷ Advertising Spend
Example: A campaign generates $40,000 in attributed revenue from $10,000 in advertising spend. The ROAS is 4.0, or 4x.
ROAS measures revenue efficiency, not profit. Whether a campaign is actually profitable depends on margins, operating costs, returns, fulfillment, and other business expenses.
Related AAMA Resources: ROAS Calculator and Break-Even ROAS Calculator
Marketing Return on Investment
Marketing return on investment measures financial return relative to the cost of a marketing investment. Organizations should define clearly which costs and returns are included in the calculation.
Formula: Marketing ROI = (Return Attributed to Marketing – Marketing Cost) ÷ Marketing Cost × 100
Example: A marketing initiative generates $150,000 in attributable financial return and costs $100,000. The marketing ROI is 50%.
Related AAMA Resource: Marketing ROI Calculator
Break-Even ROAS
Break-even ROAS estimates the minimum return on ad spend required for revenue to cover the cost structure used in the calculation. One simplified version uses gross margin.
Formula: Break-Even ROAS = 1 ÷ Gross Margin
Gross margin should be expressed as a decimal. A 25% gross margin would therefore be entered as 0.25.
Example: If a product has a gross margin of 25%, the break-even ROAS is 4.0. The advertiser would need four dollars in revenue for every dollar of ad spend to cover the gross-margin constraint used in the calculation.
Related AAMA Resource: Break-Even ROAS Calculator
Customer Acquisition & Value Formulas
Customer Acquisition Cost
Customer acquisition cost, or CAC, measures the average cost required to acquire a new customer.
Formula: CAC = Customer Acquisition Costs ÷ New Customers Acquired
Depending on the purpose of the analysis, acquisition costs may include advertising, marketing personnel, sales costs, software, agency fees, promotions, and other acquisition-related expenses.
Example: An organization spends $60,000 on customer acquisition and gains 1,000 new customers. The CAC is $60.
Related AAMA Resource: Customer Acquisition Cost Calculator
Customer Lifetime Value
Customer lifetime value, commonly abbreviated CLV or LTV, estimates the value a customer generates over the duration of the customer relationship. Organizations may use more advanced models depending on available data and forecasting needs.
A simplified approach is:
Formula: LTV = Average Purchase Value × Purchase Frequency × Average Customer Lifespan
Example: A customer spends an average of $50 per purchase, buys four times per year, and remains a customer for three years. The estimated LTV is $600.
This simplified calculation measures revenue rather than contribution margin unless margin is incorporated separately.
Related AAMA Resource: Customer Lifetime Value Calculator
LTV:CAC Ratio
The LTV:CAC ratio compares estimated customer lifetime value with the cost required to acquire that customer.
Formula: LTV:CAC Ratio = Customer Lifetime Value ÷ Customer Acquisition Cost
Example: If LTV is $600 and CAC is $150, the LTV:CAC ratio is 4:1.
The ratio should be interpreted in the context of margin, cash flow, retention, growth objectives, and the reliability of the lifetime-value estimate.
Related AAMA Resource: LTV:CAC Ratio Calculator
Customer Retention Rate
Customer retention rate measures the percentage of existing customers who remain customers over a defined period.
Formula: Retention Rate = (Customers at End of Period – New Customers Acquired During Period) ÷ Customers at Start of Period × 100
Example: A company begins the year with 1,000 customers, ends with 1,100 customers, and acquired 300 new customers during the year. The retention rate is 80%.
Retention is most meaningful when the measurement period and definition of an active customer remain consistent.
Customer Churn Rate
Customer churn rate measures the percentage of customers lost during a defined period.
Formula: Churn Rate = Customers Lost During Period ÷ Customers at Start of Period × 100
Example: A business begins the month with 2,000 customers and loses 100. The churn rate is 5%.
Churn and retention are closely related, but the calculations may not always be exact inverses when customer counts change during the measurement period.
Repeat Purchase Rate
Repeat purchase rate measures the percentage of customers who make more than one purchase during a defined period.
Formula: Repeat Purchase Rate = Customers With More Than One Purchase ÷ Total Customers × 100
Example: If 2,000 customers made purchases during the year and 800 made more than one purchase, the repeat purchase rate is 40%.
Lead Generation & Sales Formulas
Cost per Lead
Cost per lead, or CPL, measures the average marketing cost required to generate a lead.
Formula: CPL = Marketing Cost ÷ Leads Generated
Example: A campaign spends $12,000 and generates 600 leads. The CPL is $20.
Cost per lead should generally be evaluated alongside lead quality and downstream conversion rather than used by itself.
Lead-to-Customer Conversion Rate
Lead-to-customer conversion rate measures the percentage of leads that ultimately become customers.
Formula: Lead-to-Customer Conversion Rate = New Customers ÷ Leads × 100
Example: A campaign produces 1,000 leads and 100 become customers. The lead-to-customer conversion rate is 10%.
Revenue per Lead
Revenue per lead compares total revenue generated with the number of leads acquired.
Formula: Revenue per Lead = Revenue ÷ Leads
Example: A lead-generation program produces $200,000 in revenue from 2,000 leads. Revenue per lead is $100.
This metric can help compare lead sources that generate different levels of volume and customer quality.
Website & Digital Formulas
Landing Page Conversion Rate
Landing page conversion rate measures the percentage of landing-page visits that result in the intended action.
Formula: Landing Page Conversion Rate = Conversions ÷ Landing Page Visits × 100
Example: A page receives 8,000 visits and generates 320 completed forms. The conversion rate is 4%.
Related AAMA Resource: Landing Page Evaluation Checklist
Engagement Rate
Engagement rate compares defined engagement actions with an audience or exposure measure. There is no universal engagement-rate formula, so marketers should always document the denominator being used.
A common version is:
Formula: Engagement Rate = Engagements ÷ Impressions × 100
Another version may use reach, followers, sessions, or views instead of impressions.
Example: A post generates 1,000 engagements from 50,000 impressions. Using impressions as the denominator, the engagement rate is 2%.
Email Marketing Formulas
Email Delivery Rate
Email delivery rate measures the percentage of sent emails that are successfully accepted by recipient mail systems.
Formula: Delivery Rate = Delivered Emails ÷ Emails Sent × 100
Example: An organization sends 10,000 emails and 9,700 are delivered. The delivery rate is 97%.
Email Open Rate
Email open rate estimates the percentage of delivered emails that register an open.
Formula: Open Rate = Recorded Opens ÷ Delivered Emails × 100
Example: An email is delivered to 20,000 recipients and records 6,000 opens. The open rate is 30%.
Privacy protections and automatic image loading can affect open-rate accuracy, so the metric should be interpreted alongside clicks and conversions.
Email Click-Through Rate
Email click-through rate measures the percentage of delivered emails that generate a click.
Formula: Email CTR = Email Clicks ÷ Delivered Emails × 100
Example: An email is delivered to 25,000 recipients and generates 1,250 clicks. The email CTR is 5%.
Click-to-Open Rate
Click-to-open rate, or CTOR, compares the number of clicks with recorded email opens.
Formula: CTOR = Clicks ÷ Opens × 100
Example: An email records 8,000 opens and 1,600 clicks. The CTOR is 20%.
Because the calculation depends on open data, limitations in open tracking also affect CTOR.
Email Conversion Rate
Email conversion rate measures the percentage of email recipients, delivered messages, or clickers who complete a defined action. The denominator should always be stated clearly.
One common version is:
Formula: Email Conversion Rate = Conversions ÷ Delivered Emails × 100
Example: An email is delivered to 10,000 recipients and generates 300 purchases. Using delivered emails as the denominator, the conversion rate is 3%.
Related AAMA Resource: Email Marketing Metrics Calculator
Unsubscribe Rate
Unsubscribe rate measures the percentage of delivered emails that generate an unsubscribe request.
Formula: Unsubscribe Rate = Unsubscribes ÷ Delivered Emails × 100
Example: An email is delivered to 40,000 recipients and generates 200 unsubscribes. The unsubscribe rate is 0.5%.
Revenue & Commercial Formulas
Average Order Value
Average order value, or AOV, measures the average amount spent per transaction.
Formula: AOV = Revenue ÷ Number of Orders
Example: A business generates $500,000 from 10,000 orders. The average order value is $50.
AOV can help marketers evaluate pricing, promotions, cross-selling, upselling, and purchasing behavior.
Revenue per Customer
Revenue per customer measures average revenue generated by each customer during a defined period.
Formula: Revenue per Customer = Total Revenue ÷ Customers
Example: A business generates $2 million in annual revenue from 20,000 customers. Revenue per customer is $100.
Revenue Growth Rate
Revenue growth rate measures the percentage change in revenue between two comparable periods.
Formula: Revenue Growth Rate = (Current Period Revenue – Previous Period Revenue) ÷ Previous Period Revenue × 100
Example: Revenue grows from $1 million to $1.2 million. The revenue growth rate is 20%.
The periods being compared should be equivalent whenever seasonality or timing could materially affect the result.
Brand & Research Formulas
Net Promoter Score
Net Promoter Score, or NPS, is calculated from responses to a standardized likelihood-to-recommend question. Respondents are categorized as promoters, passives, or detractors.
Formula: NPS = Percentage of Promoters – Percentage of Detractors
Example: If 60% of respondents are promoters and 20% are detractors, the NPS is 40.
NPS is expressed as a score rather than a percentage and should be interpreted as one customer-experience indicator rather than a complete measure of loyalty.
Response Rate
Response rate measures the percentage of people invited to participate in a survey, research study, or direct-response activity who provide a response.
Formula: Response Rate = Responses ÷ Eligible Invitations × 100
Example: A survey is sent to 5,000 eligible participants and receives 1,000 completed responses. The response rate is 20%.
The exact denominator should reflect the methodology and exclude invalid or undeliverable invitations when appropriate.
Using Marketing Formulas Correctly
A formula can produce an accurate calculation while still producing a misleading conclusion if the underlying data is incomplete, inconsistent, or poorly defined. Before comparing results, marketers should confirm that the measurement period, attribution method, audience definition, cost inputs, conversion criteria, and data sources are consistent.
Metrics should also be interpreted together rather than in isolation. A campaign may achieve a low CPC while generating poor-quality traffic, or a high ROAS while producing insufficient profit because margins are thin. The calculation identifies what happened within a particular framework, while professional judgment determines what the result actually means.
Related AAMA Resources
Continue exploring the AAMA Resource Library with the Marketing & Advertising Glossary, Marketing Metrics & KPI Reference, Advertising & Marketing Acronyms Guide, Marketing Channels Reference Guide, Campaign Measurement Framework, and AAMA Calculators & Tools. These resources provide deeper definitions, measurement guidance, and interactive tools for many of the formulas included in this reference.
AAMA will continue expanding this reference as new platforms, measurement methods, and professional practices introduce additional calculations used throughout advertising and marketing.