"Micro SaaS Revenue Calculator: Know Your Numbers Before You Launch"
If you're building a micro SaaS, you already know the product side. But can you answer these questions without opening a spreadsheet?
- What's my LTV if I charge โฌ79/month with 4% churn?
- How long until CAC pays back at my current ARPU?
- What happens to my year-1 MRR if churn creeps from 3% to 6%?
These are the questions that separate founders who grow intentionally from those who get surprised. So I built a tool that answers all of them โ instantly, no signup, no spreadsheet.
๐ Open the Micro SaaS Revenue Calculator โ
What it calculates
ARPU (Average Revenue Per User)
If you have multiple pricing tiers, ARPU is the weighted average across them. The calculator takes up to three tiers, each with a name, monthly price, and percentage of customers on that tier. Percentages are auto-normalised so they always sum to 100% โ no manual fiddling.
With a seat multiplier, ARPU accounts for per-seat pricing:
ARPU = ฮฃ (tier_price ร tier_pct) ร avg_seats
LTV (Lifetime Value)
The standard formula: divide ARPU by your monthly churn rate.
LTV = ARPU รท monthly_churn_rate
At 3% monthly churn, the average customer stays about 33 months. At 10%, that drops to 10. This single number should inform everything from your ad spend to your support investment.
Payback Period
How many months of revenue does it take to recover your customer acquisition cost?
Payback (months) = CAC รท ARPU
If it takes longer than 12 months to recover CAC, you're financing growth โ which is fine if you have the capital, but dangerous if you don't.
LTV:CAC Ratio
The classic health metric for SaaS businesses:
- < 1x โ you're losing money on every customer
- 1โ3x โ marginal, watch costs carefully
- > 3x โ healthy, room to invest in growth
- > 5x โ possibly under-investing in acquisition
12-Month MRR Projection
The projection table simulates your first 12 months given a constant stream of net new paying customers per month and a constant churn rate. Each row shows:
- Total active customers (after churn)
- ARPU for the month
- MRR and ARR run-rate
- Customers churned that month
It's a simplified model โ it doesn't account for expansion revenue, seasonal variation, or cohort differences โ but it gives you a realistic baseline.
Churn Sensitivity Chart
The most useful visualisation: your projected MRR at month 12, plotted across churn rates from 1% to 10%. Your current churn is highlighted. This immediately shows how sensitive your business is to churn drift.
Most founders are surprised by how small a churn increase can torpedo year-1 results. Moving from 3% to 5% monthly churn often cuts projected MRR in half.
Shareable URLs & JSON export
Every scenario you calculate gets encoded into the URL as query parameters. Share it with a co-founder, drop it in a pitch doc, or bookmark it for later โ the calculator will restore your exact inputs.
The Export JSON button gives you a structured file with all inputs, computed metrics, and the full 12-month projection array. Drop it into your own spreadsheet, financial model, or investor update.
Try it
Open the calculator, plug in your actual numbers (or your planned numbers), and look at month 12. Then change churn by 2 percentage points and look again. That delta is the business case for every investment you make in retention.