CAC Payback: SGD 500 to Acquire, SGD 50/Month Revenue, 10-Month Payback = Long
E-commerce: monthly marketing spend SGD 10K, customers acquired 20. CAC = SGD 500/customer. Monthly profit per customer SGD 50 (gross profit after COGS/support). Payback: SGD 500 ÷ SGD 50 = 10 months. If customer LTV = 12 months of profit = SGD 600, payback 10 months is acceptable (ROI 20% = SGD 100 profit above CAC). But if LTV = 8 months (churn early) = SGD 400 profit, then payback is unprofitable (lose SGD 100 per customer).
- Calculating CAC
- CAC Payback Period
- CAC by Channel Variation
- AskBiz CAC Tracking
- Why Payback Period Matters More Than CAC Alone
Calculating CAC#
CAC = Total Marketing Spend ÷ New Customers Acquired. Example: spent SGD 10K on ads last month, acquired 20 customers = CAC SGD 500. Includes: ads, email, sales team, discounts. Everything that brings customer in.
CAC Payback Period#
Payback = CAC ÷ Monthly Profit per Customer. If CAC SGD 500 and customer generates SGD 50/month profit = 10 months payback. Should payback <LTV (customer lifetime). If LTV = 12 months, payback 10 months = healthy (2-month buffer). If LTV = 6 months, payback 10 months = death spiral (lose money per customer).
CAC by Channel Variation#
Paid ads: CAC SGD 500-1K (expensive, scalable). Organic/referral: CAC SGD 100-300 (cheap, limited scale). Partnerships: CAC SGD 200-500 (moderate). Most businesses mix channels: 30% paid, 50% organic, 20% partnerships. Blended CAC SGD 350. Then optimize: cut expensive channels, grow cheap ones.
AskBiz CAC Tracking#
Tracks acquisition spend and customer count by channel. Calculates CAC per channel, payback period. "Paid ads CAC: SGD 800. Organic CAC: SGD 150. Payback: paid ads 16 months, organic 3 months. Shift 30% ad spend to organic growth (content marketing, referral incentives). Projected blended CAC reduction: SGD 350 → SGD 280, payback 5.6 months → 4.5 months."
Why Payback Period Matters More Than CAC Alone#
A low CAC in isolation can mislead you if the customer generates very little monthly profit — SGD 100 CAC against SGD 5/month profit is a 20-month payback, worse than a SGD 500 CAC against SGD 100/month profit (5-month payback). Payback period = CAC ÷ monthly contribution margin per customer, and it's the number that tells you how long your cash is tied up before an acquisition becomes profitable. The rule of thumb: payback under 12 months is generally healthy for an SMB funding growth from operating cash flow; payback beyond 18 months means you're financing growth with cash reserves or debt, which is fine if deliberate but dangerous if it creeps up unnoticed. Track payback period per channel, not just blended, because a channel with attractive blended CAC can hide a much longer payback if its customers have lower monthly value than average.
Worked Example: The Channel That Looked Cheap But Wasn't#
A Singapore subscription meal-kit business ran two acquisition channels. Instagram ads: CAC SGD 180, average customer monthly profit SGD 22, payback = 180 ÷ 22 = 8.2 months. A local radio partnership: CAC SGD 340, but customers acquired via radio had notably higher basket sizes and monthly profit of SGD 55, giving payback = 340 ÷ 55 = 6.2 months — a shorter payback despite nearly double the CAC. Judged on CAC alone, Instagram looked like the better channel. Judged on payback, radio was actually more capital-efficient, because radio listeners who converted tended to be higher-intent, higher-spend customers. The business reallocated 15% of its Instagram budget toward expanding the radio partnership and saw blended payback improve from 7.4 months to 6.8 months over the following quarter — a result CAC alone would never have surfaced.
Common Mistakes When Judging Acquisition Spend#
The first mistake is comparing CAC across channels without normalising for customer quality — cheap channels often attract lower-value or higher-churn customers, and a fair comparison requires payback period, which factors in monthly profit, not just acquisition cost. The second is excluding indirect acquisition costs — sales team salaries, tools, and content production costs should be allocated into CAC even though they're harder to attribute per customer than direct ad spend; leaving them out understates true CAC and makes payback look better than it is. The third is not revisiting payback as retention changes — if churn increases, monthly average customer lifespan shortens, and a payback period that used to be safely inside your LTV window can suddenly exceed it, turning a profitable channel unprofitable without any change in acquisition cost at all. AskBiz ties acquisition spend to actual customer profit and churn data automatically, so payback period updates in real time as retention shifts rather than being recalculated only once a year.
People also ask
What CAC is acceptable?
If LTV = 12 months, CAC should be <30% of LTV = CAC <SGD 180 (if SGD 600 LTV). For SaaS: CAC <SGD 300, payback <12 months. For retail: CAC <SGD 100, payback <3 months.
How do I reduce CAC?
Improve conversion rate (same ad spend, more customers), reduce ad cost per impression, shift to cheaper channels (organic, referral), negotiate better rates with partners.
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