Customer Acquisition Cost (CAC) Calculator

A CAC calculator tells you exactly how much you spend to acquire one paying customer — the single most important number in any startup's unit economics. This free CAC calculator (Customer Acquisition Cost) uses the standard blended CAC formula (total marketing + sales spend divided by new paying customers acquired in the same period) and adds a payback-period verdict against your ARPU and gross margin. Whether you're a SaaS founder evaluating a paid channel, an e-commerce operator auditing acquisition spend, or a board member preparing for a fundraising round, getting CAC right is non-negotiable.

The CAC formula this calculator uses

Blended CAC = (total marketing spend + total sales spend in the period) ÷ (new paying customers acquired in the same period). This CAC calculator uses the blended version — the simplest and most-cited formula. Some teams prefer paid CAC (which excludes organic acquisition) or fully-loaded CAC (which adds tooling and partial salaries); when you're sub-$1M ARR, blended CAC is almost always the right number to track because it captures everything you're actually spending. Enter your total spend and your new-customer count to see your blended CAC; add ARPU and gross margin and the calculator shows your CAC payback period.

What a healthy CAC looks like

There's no universal CAC benchmark — a $200 CAC is cheap for an enterprise SaaS, ruinous for a $9.99/month consumer app. The right framing is CAC payback period: how many months of gross margin from the average customer it takes to recover their acquisition cost. Under 6 months is healthy and characteristic of well-tuned SaaS businesses; 6-12 months is acceptable for established SaaS; 12-24 months is risky and demands very low churn; 24+ months is usually unsustainable without a clear retention moat. The CAC calculator surfaces this verdict automatically when you enter ARPU and margin.

Why the CAC calculator is only the first step

Blended CAC is a starting line, not a finish line. The deeper questions a CAC calculator can't answer: which channels are subsidising which? What does CAC look like by cohort, by segment, or by month? How does CAC trend as you scale paid spend? These questions need cohort data and channel-level attribution — usually a spreadsheet, a BI tool, or a product like SegMetrics or Northbeam. Use this CAC calculator to set a baseline; use a channel-attribution stack to optimise it. The Unbuilt Lab Blueprint Pack covers per-channel CAC modelling for your specific idea inside the GTM doc.

Frequently asked questions

What is CAC (Customer Acquisition Cost)?

CAC, or Customer Acquisition Cost, is the total amount a business spends to acquire one new paying customer. It's calculated as total marketing and sales spend divided by new customers acquired in the same period. Along with LTV (Lifetime Value), CAC is the most fundamental unit-economics metric in SaaS, e-commerce, and consumer apps.

What's the difference between blended CAC and paid CAC?

Blended CAC includes ALL marketing + sales spend divided by ALL new customers (organic + paid). Paid CAC includes only paid-marketing spend divided by customers attributed to paid channels. Most early-stage teams use blended CAC because it captures total spend; scaled teams switch to paid CAC to evaluate channel performance.

What's a good CAC payback period?

Under 6 months is healthy SaaS; 6-12 months is acceptable; 12-24 months is risky and demands very low churn (under 2%/month); above 24 months is usually unsustainable. The CAC calculator surfaces a verdict automatically when you enter ARPU and gross margin. Consumer subscription apps usually target sub-6 months; B2B enterprise often runs 9-15 months.

How often should I recalculate CAC?

Monthly at minimum. CAC moves with channel saturation, seasonality, ad-platform pricing, and your team's mix of acquisition tactics. Many SaaS finance teams recalculate trailing-90-day blended CAC every Monday so the metric reflects recent reality rather than smoothed history.

Related free resources: LTV calculator · Burn Rate & Runway calculator