Investors judge SaaS companies on a handful of metrics: growth (net new MRR), retention (churn, net revenue retention) and efficiency (LTV:CAC and CAC payback). Putting them side by side shows whether growth is profitable.
How to use the SaaS Metrics Calculator
- Customers at the start of the month
- ARPA (per month)
- New customers this month
- Customers lost this month
- Expansion MRR this month
- Gross margin
- Sales and marketing spend this month
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter customers, ARPA, new and lost customers this month, expansion MRR, gross margin and sales & marketing spend.
Inputs explained
| Field | What to enter |
|---|---|
| Customers at the start of the month | A number |
| ARPA (per month) | Amount in your currency |
| New customers this month | A number |
| Customers lost this month | A number |
| Expansion MRR this month | Amount in your currency |
| Gross margin | In % |
| Sales and marketing spend this month | Amount in your currency |
What each result means
- MRR = [Customers at the start of the month]×[ARPA (per month)]
- ARR = [MRR]×12
- Net new MRR = [New customers this month]×[ARPA (per month)] + [Expansion MRR this month] – [Customers lost this month]×[ARPA (per month)]
- Customer churn = [Customers lost this month]÷[Customers at the start of the month]×100
- Net revenue retention (monthly) = ([MRR] + [Expansion MRR this month] – [Customers lost this month]×[ARPA (per month)])÷[MRR]×100
- Customer lifetime value = [ARPA (per month)]×[Gross margin]÷100÷([Customer churn]÷100)
- Customer acquisition cost = [Sales and marketing spend this month]÷max([New customers this month], 0.000001)
- LTV:CAC = [Customer lifetime value]÷[Customer acquisition cost]
- CAC payback = [Customer acquisition cost]÷([ARPA (per month)]×[Gross margin]÷100)
Example values
How the main result changes when Customers at the start of the month changes and everything else stays at the example values above:
| Customers at the start of the month | Net new MRR |
|---|---|
| 750 | 8,500 |
| 1,125 | 8,500 |
| 1,500 | 8,500 |
| 1,875 | 8,500 |
| 2,250 | 8,500 |
| 3,000 | 8,500 |
Formula
MRR = customers × ARPA; ARR = MRR × 12
Net new MRR = new + expansion − churned MRR
LTV = ARPA × GM ÷ churn; CAC = sales & marketing ÷ new customers; payback = CAC ÷ (ARPA × GM)
Worked example
Inputs: Customers at the start of the month: 1,500; ARPA (per month): $100; New customers this month: 90; Customers lost this month: 30; Expansion MRR this month: $2,500; Gross margin: 80 %; Sales and marketing spend this month: $45,000.
Results: MRR = $150,000.00; ARR = $1,800,000.00; Net new MRR = $8,500.00; Customer churn = 2 %; Net revenue retention (monthly) = 99.67 %; Customer lifetime value = $4,000.00; Customer acquisition cost = $500.00; LTV:CAC = 8 : 1; CAC payback = 6.3 months.
Frequently asked questions
Which SaaS metrics matter most?
Growth (net new MRR), churn, LTV:CAC and CAC payback.
What is a good CAC payback?
Under 12 months for SMB customers; up to 18–24 for enterprise.
What is net revenue retention?
Revenue kept from existing customers including expansion; over 100% means growth without new customers.