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SaaS Metrics Calculator

Calculate the metrics a board asks for: MRR, ARR, gross and net revenue retention, churn, LTV, CAC payback, and the LTV:CAC ratio, each with the formula used, so you can defend the number.

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How do I calculate SaaS metrics like NRR, churn, and CAC payback?

Net revenue retention is this period's revenue from the customers you had a year ago (including their expansions, contractions, and churn, but excluding any new customers) divided by what that same cohort produced a year ago. CAC payback is fully-loaded sales and marketing spend divided by new monthly recurring revenue multiplied by gross margin, expressed in months. The formulas are not the hard part; deciding what counts as a customer, whether to use gross or net margin, and which spend belongs in CAC is where two finance teams reach different numbers from identical data.

How it works

How to use this tool

  1. 1

    Enter your revenue base

    Starting MRR, new, expansion, contraction, and churned MRR for the period.

  2. 2

    Add acquisition and margin inputs

    Sales and marketing spend, new customers won, and gross margin percentage.

  3. 3

    Read every metric with its formula

    Each result shows the calculation used, so you can reconcile it against how your board defines the metric.

Definition traps

Two teams, the same data, different metrics

SaaS metrics look standardised and are not. These are the five definitional choices that most often make an investor's number disagree with yours.

Gross vs net revenue retention

Gross retention counts contraction and churn but never exceeds 100%. Net retention adds expansion and can exceed it. Quoting net retention when someone asked for gross is the most common cause of a diligence discrepancy.

What goes into CAC

Fully-loaded CAC includes sales salaries, commissions, marketing spend, tooling, and the share of leadership time spent selling. Marketing-spend-only CAC can be less than half the fully-loaded figure. Both are used in the market; only one is honest for payback analysis.

Logo churn vs revenue churn

Losing ten small customers and losing one large one produce very different revenue churn and identical logo churn. Report revenue churn for financial planning and logo churn for product and support signals, never substitute one for the other.

LTV that assumes forever

The textbook LTV formula divides margin-adjusted ARPU by churn rate, which implicitly assumes the churn rate holds indefinitely. At low churn this produces enormous, meaningless numbers. Capping LTV at a realistic horizon, 36 or 60 months, keeps it usable.

Bookings, billings, and revenue

A signed three-year contract is one bookings number, a different billings number depending on invoicing schedule, and a third revenue number recognised monthly. Mixing them in a single dashboard makes growth look like whichever definition flatters the quarter.

Benchmarks

Numbers to sanity-check against

Healthy net retention 100–120% for B2B SaaS; above 120% is strong, below 100% means the existing base is shrinking
CAC payback under 12–18 mo commonly cited target range for mid-market B2B; shorter is better for cash efficiency
LTV:CAC 3:1 or better a widely used rule of thumb; below 1:1 you lose money on every customer acquired
Annual gross churn under 10% often cited for mid-market B2B; SMB-focused businesses run structurally higher

These are widely repeated industry rules of thumb, not audited benchmarks, and they vary enormously by segment, contract length, and price point. Treat them as conversation starters rather than targets.

Where this tool stops

Where a metrics calculator stops

This computes the metrics from the numbers you type. The harder work is producing those numbers reliably every month from a billing system, a CRM, and a general ledger that disagree about what a customer is, then explaining why net retention moved four points, which requires cohort analysis, not a formula. That reconciliation is the recurring monthly cost most finance teams underestimate, and it is exactly the kind of definitional context a general-purpose AI tool has no way to know.

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FAQ

Questions finance teams ask about this tool

What is a good net revenue retention rate?

For B2B SaaS, 100% to 120% is generally considered healthy and above 120% is strong. Below 100% means your existing customer base is shrinking and every quarter of growth has to be bought with new acquisition. SMB-focused businesses run structurally lower than enterprise-focused ones, so compare against your own segment.

How is CAC payback period calculated?

Divide fully-loaded customer acquisition cost by the new monthly recurring revenue it generated, then multiply by gross margin percentage. The gross margin step matters: recovering acquisition cost from revenue you do not keep is not recovery. The result is the number of months before a customer has paid back what it cost to win them.

Should churn be calculated on customers or revenue?

Calculate both and report them separately. Revenue churn drives financial planning because it tells you what has to be replaced. Logo churn is a better early signal of product and support problems, because small customers usually leave first.

What is the difference between MRR and ARR?

ARR is simply MRR multiplied by twelve for a subscription business. The distinction that matters is that neither should include one-time fees, professional services, or usage revenue that is not contractually recurring, including them inflates a multiple that investors apply to recurring revenue only.

Why does my LTV look unrealistically high?

Because the standard formula divides by churn rate, and a low churn rate produces a very large number that assumes the customer stays for decades. Cap the calculation at a realistic horizon such as 36 or 60 months, and the resulting LTV:CAC ratio becomes something you can actually plan against.

Is this tool really free?

Yes. No signup, no email required, no usage limit. It runs entirely in your browser: nothing you type is uploaded to a server or stored anywhere. We build these because the people who find them useful are the people who eventually need a financial analyst that works the same way.

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