# SaaS Metrics Calculator (MRR, ARR, Churn, LTV, CAC)

URL: https://speedycalculator.com/calculators/finance/saas-metrics/
Last updated: 2026-10-25

> The SaaS metrics calculator brings together the key numbers for a subscription business – MRR, ARR, ARPA, net new MRR, churn, customer lifetime value, CAC, LTV:CAC and CAC payback – from a few inputs.

## Inputs

- 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

- MRR
- ARR
- Net new MRR
- Customer churn
- Net revenue retention (monthly)
- Customer lifetime value
- Customer acquisition cost
- LTV:CAC
- CAC payback

## 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)
```

## Explanation

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.

### Tips

- Use figures for the same period (a month, a quarter or a year) for every input so ratios compare like with like.
- Track the metric over time – the trend usually tells you more than a single value.
- Compare your result with industry benchmarks, which vary a lot between sectors.
- Treat the result as a starting point for a decision, then check the assumptions behind each input.

### Common mistakes to avoid

- Mixing monthly and yearly numbers in the same calculation.
- Using revenue where the formula needs profit (or the other way round).
- Forgetting hidden costs such as taxes, fees, overheads or your own time.

### Inputs explained

FieldWhat to enterCustomers at the start of the monthA numberARPA (per month)Amount in your currencyNew customers this monthA numberCustomers lost this monthA numberExpansion MRR this monthAmount in your currencyGross marginIn %Sales and marketing spend this monthAmount 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 monthNet new MRR7508,5001,1258,5001,5008,5001,8758,5002,2508,5003,0008,500

## 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.

## FAQ

**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.

**What formula does the SaaS Metrics Calculator use?**
MRR = customers × ARPA; ARR = MRR × 12.