Marketing math for solo founders
Marketing is where most solo founders lose money fastest. Without a clear view of acquisition cost, payback period, and retention, every channel looks promising for the first month and ruinous by the third. The tools in this guide replace gut feel with arithmetic — what each customer costs, how long they stay, and whether the funnel actually returns more than it consumes.
Cost to acquire
The CAC Calculator computes acquisition cost from total sales and marketing spend, then contextualises it against ARPU and gross margin so the LTV:CAC ratio is honest. The CAC Payback Calculator tells you how many months of gross profit it takes to earn that cost back — under 12 months is healthy for B2B SaaS, over 18 months means you are funding growth from your balance sheet.
The Ad Spend ROAS Calculator takes the same logic to paid ads: it shows the return on ad spend per channel and the break-even ROAS given your margin. Most ad accounts run at break-even or worse for the first 60 days; the calculator tells you whether to keep optimising or kill the channel.
Retention is the multiplier
Acquisition without retention is a leaky bucket. The Churn & Retention Calculator shows the compounding revenue impact of even a 1% improvement in monthly churn over 12-24 months. The Net Promoter Score Calculator gives you a simple way to track whether retention will improve before it shows up in the churn number.
Channel-level efficiency
Email is usually the highest-ROI channel for bootstrapped founders. The Email Marketing ROI Calculator validates that for your list — list size, conversion rate, AOV, and frequency to expected revenue per send. Compare that against the slower-but-compounding return of content with the Content Marketing Payback Calculator, which models how long an SEO investment takes to break even at realistic traffic ramps.
Test before you scale
The A/B Test Significance Calculator tells you when a result is real versus noise — most founders call winners three weeks too early at sample sizes that prove nothing. Use it before declaring a landing page a winner or before allocating more spend to a creative variant.
Common acquisition mistakes
- Under-counting CAC — excluding sales salaries, tooling, and onboarding makes unit economics look healthier than reality.
- Optimising for ROAS without margin context — a 4x ROAS at 20% gross margin is a loss; a 2x ROAS at 80% gross margin is profit.
- Calling A/B tests early — most "winners" at week one disappear at week four. The significance calculator forces patience.
- Treating churn as a customer-success problem — churn is a product-and-pricing problem in disguise.
- Scaling spend before payback period clears — pushing into a channel before CAC is recovered just multiplies cash drag.