This free MRR calculator builds the monthly recurring revenue waterfall β the movement chart that shows exactly how your ending MRR came together, line by line. Enter your starting MRR plus the five movements that change it each month: new customer MRR, expansion MRR from upgrades, reactivation MRR from win-backs, contraction MRR from downgrades, and churned MRR from cancellations. The tool totals them into your net new MRR and ending MRR, then calculates your growth rate and quick ratio so you can judge the quality of that growth, not just the headline number.
A single "MRR" figure on a dashboard tells you almost nothing about the health of the business behind it. Two companies can both report "ending MRR up 5% this month" while one is compounding cleanly and the other is bailing water out of a leaking bucket just to stay afloat. At Arb Digital, this waterfall view is one of the first things we build for a SaaS or subscription client, because it's the fastest way to see where growth is really coming from β and where it's quietly leaking out.
What This MRR Calculator Does
Unlike a simple MRR calculator that just multiplies customers by price, this one models the movement of MRR month over month β the same waterfall structure that VCs, boards, and finance teams expect to see in a SaaS metrics deck. It separates the five distinct sources of MRR change so you can see which levers are actually driving your number: are you growing mostly from new sales, or is expansion from existing customers doing the heavy lifting? Is contraction quietly eating your gains before churn even shows up?
This is the tool for the monthly movement view specifically. If you want the annualised headline number and its growth trajectory, use our ARR calculator instead; if you want every SaaS metric in one dashboard, use the SaaS metrics calculator.
How to Use It
- Starting MRR. Your monthly recurring revenue at the beginning of the period you're measuring β usually the first day of the month.
- New customer MRR. Recurring revenue from brand-new paying customers acquired during the month.
- Expansion MRR. Additional recurring revenue from existing customers who upgraded their plan, added seats, or bought add-ons.
- Reactivation MRR. Recurring revenue from customers who had previously churned and came back during the month.
- Contraction MRR. Recurring revenue lost from existing customers who downgraded their plan or removed seats, without fully cancelling.
- Churned MRR. Recurring revenue lost from customers who cancelled entirely during the month.
- Click Calculate. Your net new MRR, growth rate, quick ratio, and ending MRR all appear instantly.
The Formula / How It's Calculated
The MRR waterfall formula combines all five movements against your starting MRR:
Net new MRR = New MRR + Expansion MRR + Reactivation MRR β Contraction MRR β Churned MRR
Ending MRR = Starting MRR + Net new MRR
Growth rate is simply net new MRR expressed as a percentage of where you started: net new MRR Γ· starting MRR Γ 100. The quick ratio β a metric popularised in SaaS circles and referenced in benchmark studies from sources like Bessemer's Cloud Index β compares the "good" MRR movements to the "bad" ones: (new MRR + expansion MRR) Γ· (contraction MRR + churned MRR). A quick ratio above 4 is generally considered strong; below 1 means you're losing revenue faster than you're adding it, regardless of what the headline growth number says.
Why the MRR Waterfall Is the Most Revealing Chart in SaaS
A single ending-MRR number is a lagging, compressed summary. The waterfall is the same information decomposed into cause and effect, and that decomposition is where the real insight lives. Consider two companies that both report "MRR grew 5% this month":
- Company A added $6,000 in new MRR, $1,500 in expansion, lost $1,000 to contraction and $1,500 to churn. Net new MRR: $5,000 on a $100,000 base β clean, broad-based growth with a quick ratio around 3.0.
- Company B added $9,000 in new MRR but lost $3,000 to contraction and $4,000 to churn. Net new MRR: also $5,000 on the same $100,000 base β identical 5% growth, but a quick ratio near 1.3, meaning the sales team is working roughly three times harder just to post the same headline number.
Without the waterfall, both companies look identical on a board slide. With it, Company B's problem β a retention issue that's quietly consuming most of new sales' output β is obvious immediately. This is exactly why finance and RevOps teams build the waterfall as a standing monthly report rather than trusting the single ending-MRR figure alone.
Reading Your Quick Ratio
The quick ratio is the fastest gut-check on growth quality this calculator produces. It answers: for every dollar of MRR you lose, how many dollars are you adding? As a rough guide:
- Above 4 β strong, efficient growth; new and expansion revenue comfortably outpaces losses.
- 2 to 4 β healthy growth, typical of a solidly performing SaaS business.
- 1 to 2 β growth is happening but retention is eating a large share of it; worth investigating.
- Below 1 β you're shrinking. Losses exceed gains even if the absolute MRR number is still positive this month, because prior momentum is masking the trend.
Track quick ratio over several consecutive months rather than reacting to a single reading β one bad month can be a single large enterprise cancellation, not a systemic problem.
Two Rules That Keep an MRR Calculation Honest
Two mistakes distort MRR waterfalls more than anything else, and both are easy to avoid once you know to look for them:
- Normalise annual plans to monthly. A customer who pays $12,000 upfront for an annual plan contributes $1,000 to MRR, not $12,000 in the month they signed. Recognising the full annual payment as MRR in month one β and then a cliff to zero when they don't renew for another 11 months β creates a wildly misleading, spiky chart. Always divide annual contract value by 12.
- Never count one-off fees as MRR. Setup fees, onboarding charges, one-time professional services, and annual "true-up" invoices are real revenue, but they are not recurring revenue. Mixing them into MRR inflates the number and, worse, makes your growth rate and quick ratio meaningless because they include revenue that will never repeat.
Reference guides like Investopedia's explainer on MRR reinforce the same core principle: MRR should only ever include revenue you reasonably expect to repeat next month under the current subscription terms.
A weak quick ratio usually means retention is quietly outpacing new sales, or new sales are relying on channels that don't stick. Arb Digital builds growth and retention marketing programs for SaaS companies β from lifecycle email to paid acquisition β engineered to strengthen both sides of the waterfall at once.
See Growth Marketing Services Talk to Arb DigitalCommon Mistakes to Avoid
- Recognising the full value of annual contracts as MRR in one month. Always normalise to a monthly figure.
- Including one-time fees. Setup fees and professional services revenue don't belong in MRR.
- Lumping contraction into churn (or ignoring it). A downgrade is not a cancellation β track it separately so you can see partial revenue loss before it becomes full churn.
- Only watching the ending number. The ending MRR can rise even while your quick ratio is deteriorating β check both every month.
- Comparing quick ratio across companies of very different sizes without context. A young company with a small base can post an inflated quick ratio from one large deal; look at trend, not a single snapshot.
Related Free Tools From Arb Digital
See the annualised version of this number with our ARR calculator, or find out how much of your churned MRR is tied to your overall churn rate. For every metric in one place, use the SaaS metrics calculator, and once you know your revenue trajectory, project it forward with our revenue forecast calculator or check unit economics with the LTV:CAC ratio calculator. Browse every calculator in our free online tools hub.
Frequently Asked Questions
MRR is monthly recurring revenue β the predictable subscription revenue you expect each month. The waterfall matters more than the raw total because it shows the five separate movements (new, expansion, reactivation, contraction, churned) that combined to produce it, revealing whether growth is healthy and broad-based or masking a retention problem.
Quick ratio is (new MRR + expansion MRR) divided by (contraction MRR + churned MRR). It measures how many dollars of new revenue you add for every dollar lost. A ratio above 4 is considered strong, 2 to 4 is healthy, and below 1 means the business is shrinking despite what the headline MRR number might suggest.
Yes, but normalised to a monthly value. Divide the annual contract value by 12 and count that as the customer's monthly MRR contribution, rather than recognising the full annual payment in the month it was received.
Contraction MRR is revenue lost from an existing customer who downgraded or removed seats but is still paying something. Churned MRR is revenue lost from a customer who cancelled entirely. Tracking them separately lets you spot at-risk accounts contracting before they fully churn.
No. Setup fees, onboarding charges, and one-off professional services revenue are real revenue but not recurring, so they should be excluded from MRR entirely to keep growth rate and quick ratio calculations accurate.
Net new MRR is the change during the period: new plus expansion plus reactivation, minus contraction and churn. Ending MRR is the total after applying that change to your starting MRR β starting MRR plus net new MRR.
