CAC / Payback Period Calculator

How to Use the CAC & Payback Calculator

CAC and Payback Period — The Two Numbers That Decide Whether Your SaaS Scales

Payback = CAC ÷ (ARPU × gross margin): why a margin cut from 75% to 50% adds half again

Frequently Asked Questions

• What's the difference between paid CAC and fully-loaded CAC? +
  Paid CAC includes only paid media spend (Google Ads, Meta, LinkedIn) divided by customers acquired from paid channels. It's useful for setting bid caps and comparing paid channels. Fully-loaded CAC includes ALL sales + marketing costs — paid media, sales team salaries plus commissions, marketing tools, content, events, partnerships — divided by net new customers from ALL channels (paid + organic + referral). When investors ask for "your CAC", they almost always mean fully-loaded. Default to that for board decks; use paid CAC for channel-level optimisation.
• What's a healthy CAC payback period? +
  Bessemer's State of the Cloud 2023 bands it as 12–18 months good, 6–12 better and 0–6 best; Skok's guideline is that the best recover CAC in 5–7 months and that much beyond 12 makes profitability anaemic. Enterprise sellers with large, sticky contracts can defend a longer payback than SMB sellers, but the burden of proof rises with every month. The metric is sensitive to gross margin — at the same CAC and ARPU, 75% margin pays back in two-thirds the time of 50% margin.
• Should I include free trial users in CAC denominators? +
  No. CAC is computed on paying customers only — net new customers who actually pay. Free trial users who never convert don't contribute to revenue or LTV. Track free-to-paid conversion rate as a separate funnel metric, and use it to derive blended unit economics if needed. The denominator here is net new paying customers, full stop.
• What's the SaaS Magic Number and how does it relate to CAC? +
  The conventional SaaS Magic Number = (quarter-on-quarter change in recurring revenue × 4) ÷ prior-quarter S&M spend: how much new annualised revenue each dollar of S&M produced. This tool cannot see quarterly revenue, so it shows a proxy built from gross margin per customer × new customers × 12 ÷ S&M. Read it as the inverse of payback in years — a proxy of 1.0 means the year's gross margin from the cohort equals what it cost to acquire — and compare it period to period rather than against ARR-based thresholds.
• My LTV:CAC is 8:1 — is that good? +
  Good — Skok reports the best SaaS businesses at 7 or 8 — but check two things first. One: this tool's LTV is ARPU × margin ÷ churn, so a very low churn input inflates it; a 1% monthly churn implies an 8-year customer life, which few companies have observed yet. Two: if the ratio is real, it usually means you could spend more on acquisition and still clear 3:1, so a venture-backed company would treat it as headroom rather than a trophy. A bootstrapped company running lean may simply prefer it.
• How do I reduce CAC? +
  Three lever categories: (1) Improve conversion rate at every funnel stage — landing page conversion, trial-to-paid, sales-rep close rate. A 20% conversion lift drops CAC 17%. (2) Shift channel mix from expensive to cheap — paid Google Ads is typically the most expensive channel, organic search and partnerships are typically the cheapest. (3) Raise ARPU on the customers you already win — better pricing tiers, annual prepay incentives, upsell on win-back. ARPU lift doesn't reduce CAC directly but improves LTV:CAC, which is what investors actually watch.
• What time period should I use for CAC? +
  For investor reporting and board decks, use trailing 3 months (TTM is also common — trailing 12 months). For operational dashboards, use rolling 30 days. The trade-off: shorter periods are noisier (one big enterprise deal swings the average), longer periods are more stable but slower to detect changes. A common pattern is to report rolling 30, 60, and 90 day CAC side-by-side so management can see if acquisition is improving or deteriorating recently.
• Should I exclude organic customers from CAC? +
  Two views, both legitimate. The Bessemer convention is fully-loaded: all S&M spend divided by all new customers including organic. This reflects the reality that organic growth still has S&M cost (content marketing, SEO investment, brand spend). The alternative is "paid CAC" — paid media spend only ÷ paid-channel customers. Use paid CAC for channel optimisation (bid caps, ROAS targets) and fully-loaded CAC for investor reporting. Paid CAC is usually the higher of the two, because the loaded view spreads spend over organic customers as well.
• How does US SaaS CAC compare to ASEAN markets? +
  The formula does not change; the inputs do. Paid click prices and sales-team compensation are both higher in the US, and so is ARPU, so payback often lands in a similar band once both sides move. The structural edge available to an ASEAN-based company selling into the US is the mismatch: US-level ARPU against a lower-cost sales and marketing team. Model it explicitly — put the actual fully-loaded team cost into S&M spend and the US price point into ARPU — rather than assuming a multiple. See our MRR Calculator for the matching revenue-side math.
• I'm an ASEAN SaaS founder targeting the US — what payback period should I aim for? +
  Under 12 months. Two reasons specific to ASEAN-founded SaaS targeting US: (1) Your remote-team cost structure should produce structurally lower S&M cost than US-headquartered competitors, so a sub-12-month payback proves the cost advantage is real and gives US VCs confidence in your operating leverage; (2) US investors apply higher scrutiny to ASEAN-founded SaaS in the first deal — beating the headline Bessemer benchmark removes one of the standard objections. Once you have raised a Series A and demonstrated a consistent payback, spend more aggressively until payback drifts toward the top of Bessemer's "good" band — that is what the headroom is for.

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