CAC and LTV Math for Peptide Brands

most peptide brands have a CAC number and an LTV number and both are wrong, in the same direction, for the same reason: they're calculated on revenue instead of margin and on calendar periods instead of cohorts. that combination reliably makes a marginal business look healthy, which is why founders are surprised when the bank balance doesn't match the dashboard. here's how to do the math properly, with worked numbers.

start with contribution margin, not revenue

everything downstream depends on this number, so build it carefully. take a peptide brand with a $180 average order value and load every cost.

• —AOV: $180.00
• —COGS (product, vial, packaging): -$38.00
• —inbound freight, allocated per unit: -$2.50
• —3PL pick, pack, and materials: -$4.00
• —outbound shipping: -$9.00
• —payment processing at high-risk rates (4.5% + $0.30): -$8.40
• —refund and chargeback allowance at 3%: -$5.40
• —contribution margin: $112.70, or 62.6% of AOV

that $112.70 is the real number. it's what one order contributes before you've spent anything to acquire the customer. notice that a founder using only COGS would have calculated 79% margin and $142 of contribution — a 26% overstatement, which is exactly enough to turn a profitable CAC into a losing one without anyone noticing for a quarter.

calculate CAC the honest way

CAC equals total acquisition cost divided by new customers acquired. two decisions matter here.

first, new customers, not orders. if you acquired 400 new customers and took 550 orders in a month, dividing spend by 550 understates CAC by 27% — and the understatement grows as your repeat business grows, which means your CAC appears to improve at exactly the moment it isn't.

second, decide what goes into the numerator and be consistent. media-only CAC uses just ad spend and is the right number for evaluating media efficiency week to week. fully-loaded CAC adds agency fees, creative production, and any acquisition tooling, and it's the right number for business decisions. look at both, label them clearly, and never compare one to the other.

worked example: $28,000 in meta spend plus $6,000 agency retainer plus $3,000 creative production equals $37,000. 400 new customers. media-only CAC is $70. fully-loaded CAC is $92.50. both are true and they lead to different decisions.

LTV: in margin, by cohort, at 90 days

three rules, each of which fixes a specific way LTV gets inflated.

1. 1.measure in contribution margin, not revenue. an LTV of $420 in revenue sounds great and is unspendable. the same customer's margin LTV might be $260, and that's the number you can actually pay a CAC out of.
2. 2.measure by cohort. follow the customers who first bought in march for their own 90 days. calendar-period LTV mixes new and mature customers and hides trends entirely.
3. 3.use a fixed window — 90 days as your primary read, 180 as secondary. 'lifetime' is a projection, and early-stage projections in this category are almost always optimistic.

worked example with our $112.70 contribution margin. cohort of 400 customers. 35% place a second order within 90 days (140 customers). of those, 40% place a third (56 customers). total orders from the cohort in 90 days: 400 + 140 + 56 = 596. total contribution margin: 596 × $112.70 = $67,169. 90-day LTV per customer: $167.92.

note that repeat orders often carry slightly better margin — no acquisition-related discount, sometimes a larger basket — so this is a conservative read, which is how you want it.

the ratio, and what it actually tells you

with a fully-loaded CAC of $92.50 and a 90-day margin LTV of $167.92, the ratio is 1.82:1. that's workable but not comfortable. here's how to read the ranges:

• —under 1:1 — you lose money on every customer within the window. stop scaling and fix the offer, price, or repeat mechanism.
• —1:1 to 1.5:1 — thin. it can work with a very short payback and disciplined overhead, but you have no room for a CAC increase, and CAC always increases as you scale.
• —1.5:1 to 2.5:1 — healthy for a growing dtc brand. you're building real equity and can absorb some CAC drift.
• —2.5:1 to 4:1 — strong. you're likely under-spending; consider increasing budget until the ratio compresses toward 2.5.
• —over 4:1 — you are definitely under-spending, or your attribution is wrong and you're crediting organic demand to paid.

that last point is worth sitting with. a very high LTV:CAC ratio is not a trophy. it usually means there's profitable growth on the table you aren't taking, or that a chunk of the revenue you're attributing to ads would have arrived anyway. either way it's a prompt to investigate, not to celebrate.

payback period is the metric that governs cash

LTV:CAC tells you whether the business model works. payback tells you whether you'll survive long enough to find out. it's the number of days until cumulative contribution margin from a cohort equals what you paid to acquire it.

continuing the example: CAC of $92.50 against $112.70 of contribution margin on the first order means you're technically paid back on order one — day zero. that's an unusually strong position and it's what makes a self-funded peptide brand viable.

now change one input. raise CAC to $150 — entirely plausible at scale or in a competitive window. now the first order recovers $112.70 and you're $37.30 short. the second order arrives around day 32 for the 35% who reorder, so blended across the cohort you're paid back somewhere around day 45–60. still workable. raise CAC to $220 and payback stretches past 120 days, at which point you need either financing or a much slower growth rate.

• —under 30 days: you can grow as fast as inventory allows.
• —30–60 days: comfortable for a self-funded brand.
• —60–90 days: workable with a cash buffer and careful inventory planning.
• —90–120 days: you need capital or a slower pace.
• —over 120 days: you are financing customer acquisition from savings, and growth actively increases your risk.

one thing peptide brands specifically must factor in: a rolling reserve on a high-risk merchant account, commonly 5–10% held for six months, extends your effective payback by holding back a slice of every dollar. if your reported payback is 55 days, your cash payback is longer. model the cash, not the accounting.

the five mistakes that make bad businesses look good

1. 1.using COGS-only margin. inflates contribution by 20–30% and is the single most common error.
2. 2.dividing spend by orders instead of new customers. understates CAC and makes it look like acquisition is improving as repeat business grows.
3. 3.using platform-reported revenue. every platform claims the same sale, so summing them overstates total revenue and understates CAC. use blended.
4. 4.projecting LTV from warm cohorts. your first customers were existing patients, friends, and early adopters. they reorder at rates cold traffic never will. wait for a cold-acquired cohort to mature before letting LTV justify a higher CAC.
5. 5.ignoring payback entirely. this is how profitable businesses run out of money while growing.

LTV to CAC tells you if the model works. payback tells you if you'll still be here when it does.

how to improve each input, ranked by effort

if the math isn't working, these are the levers in order of return per unit of effort.

• —raise AOV. bundles, multi-month supply, subscribe-and-save, a paired second product. a $30 AOV increase flows almost entirely to contribution margin and requires no ongoing spend. this is the highest-leverage lever in the list and the one most brands skip.
• —improve repeat rate. refill reminders timed to the actual usage cycle, post-purchase education that gets people using the product correctly, and a genuine subscription option. moving from 25% to 40% repeat changes your entire spend requirement.
• —reduce COGS at volume. supplier renegotiation on run three or four, once you have real volume to trade on.
• —improve site conversion rate. it lowers CAC directly and it's usually the cheapest media-side improvement available.
• —improve creative. more angles and higher volume lowers CPA over time. real but slower and noisier than the levers above.
• —reduce processing costs. worth doing at scale, but never trade redundancy for a lower rate. a cheaper single processor is a false economy.

for context on what good acquisition efficiency looks like at scale, wayyless ran $4.3M in spend to $19.1M in revenue — a 4.45 blended ROAS. that's the acquisition side working. the retention side is what determines whether numbers like that compound into a durable business or just a large, expensive one. your own results will depend on your offer, market, and cost structure, and none of this is financial advice — build your model with your accountant.

a simple monthly routine

1. 1.recompute contribution margin per order with actual costs from the month, not last quarter's assumptions.
2. 2.compute CAC both ways — media-only and fully loaded.
3. 3.pull the cohort that just crossed 90 days and compute its margin LTV.
4. 4.compute LTV:CAC and payback in days, including the effect of any merchant reserve.
5. 5.reconcile: does modeled contribution margin times orders match actual gross profit? if not, find the missing cost.
6. 6.then, and only then, decide next month's budget.

that whole routine takes about two hours and it's the difference between scaling deliberately and scaling hopefully.