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A free tool · Ling Koay

The B2B growth math
every founder
should know.

LTV, CAC, payback, the ratio. Move a slider, watch the whole system respond. Built to sharpen the conversation between founders, boards and their CMO — not replace it.

Revenue = Customers × ARPU × 12
01 — Inputs
Revenue inputs
Monthly ARPU
$850
Active paying customers today
800
Revenue target (ARR)
$25M
02 — Inputs
Cost & margin
Gross margin
75%
Annual media spend
$1.5M
03 — Inputs
Acquisition mix
% via organic / partner
55%
55% organic / partner 45% paid ads
Paid CAC per customer
$5,500
Organic / partner CAC
$350
04 — Inputs
Retention inputs
Annual churn rate
10%
Trial → paid conversion
7%
05 — Constraint
Your payback target
Max months to recover CAC
12
18
24
36
01 — Output
Monthly gross profit / customer
What you keep per customer per month
—
per month
= ARPU × Gross margin
02 — Output
Lifetime value
Total earned from one customer over 5 years (survival-weighted)
—
5-year LTV
= Σ (Monthly GP × 12 × survival_yr) yr 1..5
03 — Constraint
Max allowable CAC
Do not exceed to stay inside payback target
—
= Monthly GP × payback months
04 — Reality check
Blended CAC & payback period
Blended CAC today
—
at current channel mix
Payback period
—
months
—
Month 0 (CAC paid) 18-month target Month 36+
05 — The ratio
LTV : CAC ratio
Return on acquisition investment
—
× LTV per CAC
LOSE
WATCH
GROW
SCALE
0:13:1 →5:1 →10:1+
06 — Retention
Customer survival curve
What % of this month's customers are still paying at year N?
Survival = (1 − annual churn)years  ·  50% gone by year —
07 — The levers
If this changes, that changes
08 — Channel economics
Channel economics at your current mix
ChannelCACPaybackStatus
Blended CAC = organic% × organic CAC + paid% × paid CAC
09 — Target math
Customers to hit target
At your current ARPU
—
—
10 — Lines in the sand
Where each input breaks the 3:1 floor
11 — Before the board meeting
Five questions that fix all assumptions
Ask these before you build the plan — most decks miss at least two.
Q1 → Fixes ARPU
"How many active paying customers do you have today — and how do you define 'active'?"
Fixes: ARPU, LTV, customers-to-target
Q2 → Fixes CAC
"Of your total marketing budget — how much is headcount vs pure media spend?"
Fixes: the entire CAC calculation
Q3 → Fixes LTV
"What is actual annual churn — and does it differ by acquisition channel?"
Fixes: LTV, survival, payback
Q4 → Fixes paid CAC
"What's your trial-to-paid conversion — and do you track it by channel?"
Fixes: paid CAC, wasted spend
Q5 → Fixes channel mix
"Where do new customers actually come from — partners, organic, or paid?"
Fixes: blended CAC, what to scale

Want help turning this
into your actual plan?

I work with founders and marketing leaders as a Fractional CMO and brand advisor — helping you build a marketing engine the numbers can actually carry.

Let's talk Work with me