MRR vs ARR: The Complete Guide to SaaS Revenue Metrics
How MRR and ARR are calculated, when to use each, and how to break revenue down into new, expansion, contraction, and churned MRR for an accurate growth picture.
Ask five SaaS founders how they calculate MRR and you'll often get five slightly different answers — and the differences are rarely cosmetic. Whether you count an annual contract as a lump sum or a monthly slice, whether a downgrade counts as churn or contraction, and whether a one-time setup fee belongs in the number at all — each of these choices changes the figure you put in front of investors, your board, and yourself.
This guide lays out exactly how MRR and ARR are calculated, the movement components that explain why a number changed (not just that it did), and the related metrics — NRR in particular — that tell you whether your growth is durable or borrowed from next quarter.
MRR and ARR, defined precisely
Monthly Recurring Revenue (MRR) is the predictable revenue your business can expect to receive every month from active subscriptions, normalized to a monthly figure. Annual Recurring Revenue (ARR) is the same concept annualized — the recurring revenue your subscription base represents over a full year.
The two core formulas
MRR = Σ (monthly value of every active subscription)
ARR = MRR × 12
The part that trips people up is "monthly value." If a customer pays $1,200 once a year, their monthly contribution to MRR is $100 — not $1,200 in the month they happen to pay, and not $0 in the eleven months they don't. Normalizing every contract to a monthly figure before summing is what keeps MRR meaningful as a forward-looking, comparable number rather than a snapshot of cash that happened to land this month.
A useful gut check: if your MRR jumps sharply in one month and falls back the next, with no corresponding change in your customer base, you are very likely looking at a normalization issue rather than real growth or real churn.
What belongs in MRR — and what doesn't
- Include: subscription fees, recurring add-ons, recurring usage commitments, and recurring seat-based charges — anything a customer is contractually expected to keep paying.
- Exclude: one-time setup or onboarding fees, professional services, training, hardware sales, and discretionary usage spikes that don't reflect a contractual commitment.
The reasoning is simple: MRR is a predictive number. Its entire value lies in telling you, with reasonable confidence, what next month looks like. Mixing in non-recurring revenue makes the number louder in good months and misleading in the months that follow.
The MRR movement breakdown — where the real story lives
A single MRR figure tells you where you are. The movement breakdown tells you how you got there — and that's the part that actually drives decisions. Every month, your MRR change is the sum of five components:
| Component | What it represents |
|---|---|
| New MRR | Recurring revenue from brand-new customers acquired this period |
| Expansion MRR | Additional revenue from existing customers upgrading, adding seats, or buying add-ons |
| Contraction MRR | Revenue lost from existing customers downgrading or reducing usage (they're still active) |
| Churned MRR | Revenue lost from customers who cancelled entirely |
| Reactivation MRR | Revenue from previously churned customers who came back |
Net New MRR
Net New MRR = New + Expansion + Reactivation − Contraction − Churned
Two companies can post the exact same Net New MRR and be in completely different positions. One might be growing almost entirely from new logos while quietly losing existing customers — a leaky bucket that requires ever-increasing sales effort just to stand still. The other might be growing mostly from expansion within a stable base — a much more durable, compounding pattern. The aggregate number can't tell them apart. The breakdown always can.
Net Revenue Retention: the metric that reveals whether growth compounds
Net Revenue Retention (NRR) measures how the revenue from your existing customer base changes over a period — completely independent of new sales. It answers a deceptively important question: if we stopped signing new customers today, would our revenue from the current base grow, hold steady, or shrink?
Net Revenue Retention
NRR = (Starting MRR + Expansion − Contraction − Churn) ÷ Starting MRR × 100
- NRR above 100% — your existing customers alone are growing revenue. This is the strongest signal of durable product-market fit; growth compounds even before counting new sales.
- NRR around 100% — expansion is roughly offsetting contraction and churn. Stable, but new sales are doing all the heavy lifting for growth.
- NRR below 100% — the existing base is shrinking in revenue terms. New sales are not just fueling growth; they're backfilling a hole, which becomes unsustainable as acquisition costs rise.
This is also why experienced operators and investors look at NRR alongside topline MRR/ARR growth rather than either number alone — strong topline growth can mask a retention problem for several quarters before it becomes impossible to ignore.
Try it yourself
MRR & ARR Calculator
Model net new MRR, ARR, NRR, and month-over-month growth with a full breakdown of new, expansion, contraction, and churned revenue.
Practical guidance for tracking these numbers well
- Normalize every contract to a monthly value before it enters your MRR — annual, quarterly, and usage-based contracts alike. This single habit prevents most of the "why did MRR spike for no reason" conversations.
- Track the five movement components separately, not just the net change. The net number can stay flat while the underlying story — strong new sales masking serious churn, for example — changes completely.
- Report NRR alongside MRR/ARR growth, especially to investors and your board. A growth number without a retention number is, at best, half the picture.
- Keep one-time revenue in a separate line entirely. It's real revenue and worth tracking — it just isn't recurring revenue, and conflating the two erodes the predictive value of the metric you built it for.
Frequently asked questions
Is ARR just MRR multiplied by 12?
For a stable subscription base, yes — ARR is conventionally calculated as MRR × 12. The nuance is what you do with annual-plan customers: most operators normalize annual contracts down to a monthly figure before multiplying back up, so a single annual deal doesn't create a misleading spike in either metric.
Should one-time fees count toward MRR?
No. MRR is meant to represent predictable, recurring revenue — the number you can reasonably expect to repeat next month. Setup fees, professional services, and other one-time charges should be tracked separately so they don't inflate your sense of recurring revenue health.
What's the difference between churned MRR and contraction MRR?
Churned MRR is revenue lost because a customer cancelled entirely. Contraction MRR is revenue lost because an existing customer downgraded to a cheaper plan or reduced seats — they're still a customer, just paying less. Separating the two matters: high contraction with low churn often signals a pricing or packaging problem rather than a retention problem.
Why does Net Revenue Retention matter more than headline growth?
NRR isolates how your existing customer base behaves — expansion and contraction and churn — independent of new sales. A company can show strong topline growth purely from new logos while its existing base quietly leaks revenue every month. NRR above 100% means your existing customers alone would grow your revenue even if you closed zero new deals; that's the clearest signal of product-market fit compounding on itself.
Once you've normalized your contracts and separated the five movement components, modeling next month's number — and seeing exactly which lever moves it most — becomes straightforward arithmetic. The MRR & ARR Calculator above runs that full breakdown for you, including NRR, in real time.