Customer acquisition cost (CAC) is the total sales and marketing spend a business incurs to win one new customer over a defined measurement window. The customer acquisition cost formula divides the sum of all sales expenses and marketing expenses by the number of new customers acquired during that same period — expressed as (Sales Expenses + Marketing Expenses) / New Customers Acquired — making it a direct measure of commercial efficiency at the ledger level. Sales and marketing expenses counted in the numerator include salaries, ad spend, software subscriptions, sales commissions, and agency fees, while the denominator records only net-new customers won within the chosen time period, not renewals or upsells. Each expense category maps to a dedicated chart-of-accounts line — salaries under payroll, ad spend under advertising, subscriptions under software — so the CAC numerator can be assembled directly from a general-ledger export. Cost per lead — the spend divided by leads generated rather than customers won — is a distinct upstream metric that feeds into CAC but does not replace it, because it omits the conversion step from lead to paying customer. A business spending $50,000 on sales expenses and $30,000 on marketing expenses while acquiring 200 new customers in a quarter carries a CAC calculator result of $400 per customer. CAC is evaluated alongside two companion metrics — the LTV:CAC ratio, which compares customer lifetime value to acquisition cost, and the CAC payback period, which measures how many months of gross margin are needed to recover that $400 — and it is reported in two primary variants: blended CAC, which pools all channels, and paid CAC, which isolates only paid-channel spend.
CAC = (marketing spend + sales spend) ÷ new customers acquired; payback = CAC ÷ monthly revenue per customer
Add up everything spent on winning customers in a period, divide by the customers actually won, and you get the price of one customer. Divide that by what a customer pays you monthly and you get how many months of their revenue the acquisition consumed.
How to calculate the cost of acquiring a customer?
To calculate the cost of acquiring a customer, divide the total sales and marketing expenses incurred during a defined measurement window by the number of new customers won during that same period. The formula is (Sales Expenses + Marketing Expenses) / New Customers Acquired, where the numerator captures every dollar spent to generate and close new business, and the denominator counts only customers who completed a first purchase or signed a first contract within the window. The measurement window must be fixed before any inputs are pulled — a 30-day window and a 90-day window will produce different customer acquisition cost figures even when the underlying spend rate is identical.
The numerator of the customer acquisition cost formula draws from specific expense line items recorded in the chart of accounts. Sales expenses include sales-team salaries, sales commissions paid on new contracts, and sales-software subscriptions such as CRM licenses. Marketing expenses include paid-media ad spend across all channels, agency and contractor fees, content-production costs, and marketing-platform subscriptions. A fully-loaded customer acquisition cost calculation also folds in the allocated portion of sales-leadership salaries and any overhead directly attributable to the sales and marketing function, a convention documented in named SaaS unit-economics writing such as David Skok's "SaaS Metrics 2.0" framework on ForEntrepreneurs.com.
The denominator requires a precise definition of "new customer" that aligns with the company's revenue-recognition policy. A new customer is a business entity or individual that generated its first recognized revenue event within the measurement window — reactivated lapsed accounts and upsell revenue from existing customers are excluded, because including them would deflate the customer acquisition cost figure and misrepresent the efficiency of new-business acquisition spend. For a SaaS business billing $500 per month per seat, a customer counts as acquired when the first invoice is recognized, not when a trial begins. For a professional-services firm, the acquisition event is the signed engagement letter, consistent with the accrual-basis revenue-recognition standard under ASC 606.
A worked example clarifies the calculation. A B2B software company records $120,000 in sales-team salaries, $45,000 in paid-media spend, $15,000 in agency fees, and $20,000 in CRM and marketing-automation subscriptions over a single calendar quarter — a total numerator of $200,000. During that same quarter, the company signs 80 new customers. Dividing $200,000 by 80 produces a customer acquisition cost of $2,500 per new customer. If the company then separates paid-channel spend ($45,000 in ad spend + $15,000 in agency fees = $60,000) and attributes 25 of the 80 new customers to paid channels, the paid CAC for that channel is $2,400 ($60,000 / 25), while the blended CAC across all channels remains $2,500. The gap between paid CAC and blended CAC signals how much of the acquisition load organic and referral channels are carrying.
Calculating customer acquisition cost by channel requires tagging each new customer to the channel that sourced the first meaningful engagement, a process that depends on consistent UTM tracking and CRM pipeline-source fields. Channel-level customer acquisition cost figures feed directly into the LTV:CAC ratio analysis, where a ratio below 3:1 in a SaaS context typically indicates that the cost of acquiring customers is consuming an unsustainable share of customer lifetime value, a benchmark reflected in SaaS Capital's annual "Benchmarks for Private SaaS Companies" study. The CAC payback period — calculated as customer acquisition cost divided by the monthly gross-profit contribution per customer — translates the ratio into months of revenue required to recover the acquisition investment, giving finance teams a time-based measure alongside the ratio-based one.
How to calculate customer acquisition cost in Excel?
To calculate customer acquisition cost in Excel, enter total sales expenses in one cell, total marketing expenses in a second cell, new customers acquired in a third cell, and then divide the sum of the first two cells by the third using the formula =(B2+C2)/D2, where B2 holds sales expenses, C2 holds marketing expenses, and D2 holds new customers acquired over the measurement window. This spreadsheet structure mirrors the canonical CAC formula: (Sales Expenses + Marketing Expenses) / New Customers Acquired and produces a single blended CAC figure per period. The formula scales across multiple rows when each row represents a distinct time period — a month, a quarter, or a fiscal year — so the workbook builds a running CAC trend without manual recalculation.
A fully-loaded CAC model in Excel expands the numerator across several expense line items rather than a single aggregated figure. Column B captures sales team salaries and commissions, column C captures paid advertising spend, column D captures software subscriptions and CRM licensing fees, column E captures agency and contractor fees, and column F captures any trade-show or event costs attributable to customer acquisition. The master CAC cell then reads =(SUM(B2:F2))/G2, where G2 is the new-customer count for that period. This column-per-expense-category layout maps directly to the chart of accounts structure that accounting teams already maintain, making it straightforward to pull figures from a general ledger export into the spreadsheet without reclassifying entries.
Channel-level customer acquisition cost requires a separate tab per acquisition channel — paid search, organic, referral, and outbound — with each tab carrying its own version of the =(Sales Expenses + Marketing Expenses) / New Customers Acquired formula scoped to that channel's spend and customer count. A summary tab then consolidates channel-level CAC figures alongside blended CAC, enabling a direct comparison. A business spending $18,000 USD on paid search in a quarter and winning 45 new customers from that channel records a paid CAC of $400 per customer, while a referral program costing $3,000 and generating 30 new customers yields a referral CAC of $100 per customer — a 75% lower cost per acquisition from the referral channel.
The LTV:CAC ratio column extends the Excel model by adding a customer lifetime value input alongside the CAC output. If column H contains the LTV figure — calculated separately as average revenue per customer multiplied by gross margin percentage and average customer lifespan — then column I can read =H2/I2 to produce the ratio automatically for each period row. A ratio of 3:1 or higher is the widely cited benchmark for sustainable unit economics across SaaS and subscription business models, as documented in David Skok's "SaaS Metrics 2.0" framework on ForEntrepreneurs.com. The CAC payback period, expressed in months, occupies a further column using the formula =CAC / (Monthly Recurring Revenue per Customer × Gross Margin %), giving finance teams a second output metric alongside the ratio without requiring a separate workbook.
Common mistakes in Excel-based CAC models include double-counting customers who churned and re-subscribed within the same measurement window, and mixing fiscal-period boundaries so that December ad spend is paired with January new-customer counts. Some fully-loaded CAC frameworks include the non-cash portion of stock-based compensation for sales and marketing staff, though standard blended CAC calculations typically exclude non-cash items; finance teams should apply a consistent policy and disclose it when reporting CAC to investors. Each boundary or classification error inflates or deflates the denominator or numerator independently, producing a CAC figure that does not reflect the true all-in cost to win one customer. Locking the measurement window as a named range — for example, defining Period_Start and Period_End as named cells and referencing them in every expense and customer-count pull — eliminates boundary mismatches and keeps the Excel CAC calculation internally consistent across every row and tab in the workbook.
An agency spends $6,000 on marketing and $4,000 on sales in a month and signs 25 new clients paying $250 a month each.
The $10,000 of combined spend buys 25 clients at $400 each. At $250 of monthly revenue per client, acquisition pays back in 1.6 months of revenue — a healthy leash before delivery costs.
A shop spends $9,000 on ads in a month and lands 300 first-time buyers.
$30 per new customer. Whether that works depends entirely on order value and repeat rate — on a $40 first order it needs buyers to come back; on a $120 order it prints money.
The calculation for customer acquisition cost is (Total Sales Expenses + Total Marketing Expenses) ÷ New Customers Acquired over a defined measurement window, producing a dollar figure that represents the all-in cost to win one new paying customer. The formula is expressed consistently across the dominant SERP sources and mainstream SaaS unit-economics guides. Every variable in the formula maps directly to a line item on the income statement, making customer acquisition cost a ledger-grounded metric rather than an estimate.
The numerator captures all sales and marketing spend attributed to the measurement period. Expense categories that belong in the numerator include sales-team salaries and commissions, marketing-team salaries, paid advertising spend across all channels, software subscriptions used exclusively for sales or marketing functions, agency and contractor fees, and event or sponsorship costs. A business that spent $120,000 USD on sales expenses and $80,000 USD on marketing expenses in a single fiscal quarter places $200,000 in the numerator. Omitting any one of these line items produces an understated CAC figure, a distortion that causes the LTV:CAC ratio to appear more favorable than the underlying economics support.
The denominator is the count of net-new customers acquired during the same measurement window used for the numerator. A customer acquired through a free-trial conversion, a direct sales close, or a channel-partner referral all counts toward this figure, provided the acquisition event falls inside the defined period. Using a mismatched window — for example, dividing a full-year numerator by a single-quarter denominator — is the most common calculation error in customer acquisition cost reporting. Aligning the numerator period and the denominator period to the same calendar interval eliminates this distortion.
Applying the formula to a concrete example: a SaaS business that records $150,000 in sales expenses and $90,000 in marketing expenses during Q1, and closes 300 net-new customers in that same quarter, produces a blended CAC of $800 per customer ([$150,000 + $90,000] ÷ 300). Blended CAC aggregates spend across all acquisition channels — paid search, organic, referral, and outbound — into a single average. Paid CAC, a narrower variant, isolates only paid-channel spend in the numerator and only customers attributed to paid channels in the denominator, producing a channel-specific cost figure that sits alongside the blended rate rather than replacing it.
Fully-loaded CAC extends the numerator further by including overhead allocations — office space, recruiting costs for sales and marketing roles, and tools shared across departments — that standard blended CAC omits. The fully-loaded variant is the most conservative and most complete measure of customer acquisition cost, and it is the figure most relevant to unit-economics analysis for enterprise finance teams and investor reporting. The gap between blended CAC and fully-loaded CAC can be material, and named SaaS benchmarking sources such as OpenView Partners' annual SaaS Benchmarks report document meaningful spreads between the two variants. Tracking all three variants — blended, paid, and fully-loaded — gives finance and accounting teams a complete picture of the cost structure behind each new customer won.
An acceptable customer acquisition cost is one that remains below the revenue a customer generates over their relationship with the business, most commonly benchmarked against the LTV:CAC ratio, where a ratio of 3:1 — meaning customer lifetime value is at least three times the cost to acquire that customer — is the widely cited threshold for sustainable unit economics, as established in David Skok's SaaS metrics framework published on ForEntrepreneurs.com. A ratio below 2:1 signals that acquisition spending is consuming too large a share of customer revenue, while a ratio above 5:1 may indicate underinvestment in sales and marketing that leaves growth on the table.
Acceptable CAC levels vary materially by business model, average contract value, and sales cycle length. SaaS businesses with annual contracts in the $10,000–$50,000 range commonly carry a CAC between $1,000 and $5,000 per new customer, a range consistent with figures reported in the KeyBanc Capital Markets SaaS Survey (the successor to the Pacific Crest SaaS Survey). E-commerce businesses operating on thin gross margins commonly require a substantially lower CAC per customer, because the shorter customer lifespan compresses the lifetime value available to absorb acquisition cost. Professional-services firms with multi-year client relationships and higher gross margins can sustain a materially higher per-customer CAC, provided the CAC payback period — the number of months of gross profit required to recover the acquisition cost — stays within a business-appropriate window, as commonly observed in advisory and consulting engagements.
The CAC payback period is a second benchmark that operates alongside the LTV:CAC ratio. A payback period under 12 months is considered healthy for most B2B software and services businesses, a threshold documented in OpenView Partners' SaaS Benchmarks reporting on growth-stage software companies. Payback periods exceeding 24 months place significant strain on working capital, because the business must fund the acquisition cost for two full years before recovering it through gross profit, a pattern that compounds when new-customer volume is growing rapidly.
Gross margin is a critical modifier when judging whether a given CAC is acceptable. A business with 80% gross margins recovers acquisition cost far faster than one with 40% gross margins at the same CAC and same monthly revenue per customer. The LTV:CAC ratio calculation must therefore use gross-margin-adjusted lifetime value — not raw revenue — to produce a ratio that reflects true profitability. Comparing CAC against unadjusted revenue overstates the business's capacity to absorb acquisition spend and produces an artificially favorable ratio.
Channel mix also shapes what counts as an acceptable blended CAC. Paid-channel CAC, which isolates the cost of customers won through paid advertising and paid sales outreach, consistently runs higher than organic or referral CAC, because it carries the full weight of media spend and sales-commission costs with no offset from inbound demand. A blended CAC that appears acceptable at the portfolio level can mask an unsustainable paid-channel CAC if organic and referral volume is declining, making channel-level cost reporting an essential complement to the top-line CAC figure. Businesses that track marketing ROI at the channel level can identify which acquisition channels produce a CAC that falls within the 3:1 LTV threshold and reallocate spend accordingly.