SaaS Metrics Calculator — MRR, ARR & Churn

Guide

About the SaaS Metrics Calculator

The SaaS Metrics Calculator turns your month-over-month customer and revenue changes into the core metrics every subscription business is measured on: Monthly Recurring Revenue (MRR), Annual Recurring Revenue (ARR), churn rate, and Net Revenue Retention (NRR). Instead of tracking these manually in a spreadsheet, enter your starting MRR and customer count along with this month's new, churned, expansion, and contraction activity, and the calculator builds a full MRR waterfall automatically.

How It Works

New MRR comes from new customers multiplied by their average revenue. Churned MRR comes from churned customers multiplied by their average revenue. Net New MRR adds New MRR and Expansion Revenue, then subtracts Churned MRR and Contraction Revenue. Ending MRR is Starting MRR plus Net New MRR, and ARR is simply Ending MRR × 12. Customer Churn Rate divides churned customers by starting customers; Revenue Churn Rate divides churned MRR by starting MRR; and Net Revenue Retention measures how your existing base alone trended, before counting any new customers.

Why It Matters

MRR and ARR tell you the current size of the business, but churn and NRR tell you whether that size is sustainable. A business can grow MRR every month purely from new sales while quietly leaking existing customers — the churn and NRR figures expose that. NRR above 100% is one of the strongest signals in SaaS: it means your existing customers alone are growing revenue through expansion faster than you're losing it to churn and downgrades, which is exactly what investors and operators look for.

Tips for Accurate Results

Use actual billing data for new, churned, expansion, and contraction amounts rather than estimates — MRR waterfalls are sensitive to small errors.
Track customer churn and revenue churn separately; they tell different stories, especially if your customer base includes a mix of small and large accounts.
Recalculate every month to build a trend line for NRR — a single month's NRR is noisy, but a consistent trend is meaningful.
Don't net expansion and contraction together before entering them — keeping them separate makes the waterfall chart and breakdown table much more useful.

Formula

How MRR, ARR and NRR are Calculated

Ending MRR builds up from starting MRR plus every change during the month.

SaaS Metrics Formulas

Ending MRR = Starting MRR + New MRR + Expansion − Churned MRR − Contraction
ARR = Ending MRR × 12
NRR % = (Starting MRR + Expansion − Churned MRR − Contraction) ÷ Starting MRR × 100

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MRR Waterfall

Break MRR growth into New, Expansion, Churned, and Contraction to see exactly where growth (or leakage) is coming from.

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NRR Excludes New Sales

Net Revenue Retention isolates your existing customer base — a true measure of product stickiness and expansion, separate from sales growth.

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Track Both Churn Rates

Customer churn and revenue churn can diverge significantly. Track both to understand whether you're losing small accounts, large accounts, or both.

FAQ

Frequently Asked Questions

Common questions about SaaS metrics

What's the difference between MRR and ARR?

MRR (Monthly Recurring Revenue) is your predictable subscription revenue per month. ARR (Annual Recurring Revenue) is simply MRR × 12 — the annualized run-rate. MRR is used for short-term tracking; ARR is used for annual planning and investor reporting.

What's a good churn rate for SaaS?

For SMB-focused SaaS, monthly customer churn under 5% is considered healthy; for enterprise SaaS with longer contracts, under 1% monthly is the benchmark. Lower is always better, and even small differences compound significantly over a year.

What is Net Revenue Retention and why do investors care?

Net Revenue Retention (NRR) measures revenue growth from your existing customer base alone, including expansion and excluding new customers. NRR over 100% means expansion revenue (upsells, upgrades) outpaces revenue lost to churn and downgrades — meaning your existing base grows revenue even with zero new sales, which investors view very favorably.

Why do customer churn and revenue churn differ?

Customer churn counts lost accounts as a percentage of total customers. Revenue churn counts lost MRR as a percentage of total MRR. If the customers who churn tend to be smaller (or larger) than average, the two rates diverge — losing many small accounts can look worse on customer churn than on revenue churn, and vice versa.

What counts as expansion vs. contraction revenue?

Expansion revenue comes from existing customers upgrading plans, adding seats, or buying add-ons. Contraction revenue is the opposite — existing customers downgrading or removing seats without fully canceling. Both are tracked separately from new and churned MRR because they reflect how your current base is trending.

How is Ending MRR calculated from my inputs?

Ending MRR = Starting MRR + New MRR + Expansion Revenue − Churned MRR − Contraction Revenue, where New MRR is New Customers × Avg. Revenue per New Customer and Churned MRR is Churned Customers × Avg. Revenue per Churned Customer. This full build-up is shown line by line in the MRR Waterfall table.

How is ARR calculated, and why is it just MRR × 12?

ARR (Annual Recurring Revenue) is calculated as Ending MRR × 12 — a simple annualized run-rate based on your current month's recurring revenue, not a forecast that accounts for future growth or churn. It's useful for annual planning and investor reporting, while MRR remains the number to track month to month.

Can Net Revenue Retention be higher than 100%?

Yes, and it's a strong positive signal when it is. NRR above 100% means expansion revenue from your existing customers (upgrades, add-ons, seat growth) more than offset the MRR lost to churn and contraction, so your existing base alone grew revenue even before counting any new customers.

Why does the calculator ask for average revenue per new and churned customer instead of total new/churned MRR directly?

Multiplying customer counts by an average revenue figure keeps the customer-level and revenue-level numbers consistent, which is what lets the calculator compute both customer churn rate and revenue churn rate from the same inputs. If you already know your exact New MRR or Churned MRR totals, just divide by the customer count to get the average revenue figure to enter.

What does the MRR Waterfall chart show?

It's a bar chart of the four components that move MRR during the month — New MRR and Expansion Revenue shown as gains, Churned MRR and Contraction Revenue shown as losses — so you can see at a glance which forces are driving your net change, beyond just the final Ending MRR number.

Can I use this calculator for a period other than one month?

The calculator is built around a monthly cadence (MRR, monthly churn, month-over-month waterfall), which is the standard reporting period for SaaS metrics. You can still enter figures for a different period, such as a quarter, but the churn rate and NRR outputs would then represent that period rather than a true monthly rate.

What's the difference between Net Revenue Retention and Gross Revenue Retention?

Net Revenue Retention (calculated here) includes expansion revenue, so it can exceed 100%. Gross Revenue Retention excludes expansion entirely and only accounts for churn and contraction, so it's capped at 100% — it measures pure revenue retention without any credit for upsells, giving a more conservative view of how "sticky" your base is.

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