What Is MRR and ARR? The Two Numbers That Run a SaaS

MRR is your monthly recurring revenue: the predictable amount of subscription money your customers pay you every single month. ARR is the annual version of the same thing, your yearly recurring revenue, which for most businesses is simply MRR times twelve. Think of MRR as the speed your business is traveling right now and ARR as how far that speed would carry you in a year. In this guide I will define both numbers clearly, show you the exact math with real figures, explain the moving parts that push them up and down, and warn you about the common mistakes that quietly inflate them.

What is MRR and ARR, really?

The whole reason these two numbers exist is that subscription businesses are different from one-time-sale businesses. If you run a shop, last month's sales are gone and this month you start from zero. But in a SaaS business, the customer you signed last month is usually still paying this month, so revenue stacks. MRR is the metric that captures that stacked, recurring base.

MRR is the sum of all your recurring subscription revenue, normalized to a monthly figure. The word recurring matters: it only counts money you can reasonably expect to receive again next month. A one-time setup fee or a one-off consulting charge does not belong in MRR, because it will not repeat. If a customer pays you 50 dollars a month, that is 50 dollars of MRR. If another pays 1,200 dollars a year, that is 100 dollars of MRR (1,200 divided by 12), because you normalize annual plans down to a monthly figure.

ARR is just MRR viewed over a full year. The simple and standard formula is ARR = MRR times 12. So if your MRR is 8,000 dollars, your ARR is 96,000 dollars. ARR does not mean you have collected that money already; it means that at your current run rate, you are on track to earn that much over the next twelve months. Founders tend to talk in ARR for the headline number ("we just crossed 1 million ARR") and manage in MRR for the month-to-month detail.

The exact math, with numbers

Let me make it concrete. Imagine on the first of the month you have these customers on these plans.

Notice customer C pays you 2,400 dollars up front for the year, but in MRR terms they count as 200 dollars (2,400 / 12), the same as monthly customer B. You normalize everyone to a monthly number so you can compare and add them up cleanly. Your total MRR here is 500 dollars, which makes your ARR 500 times 12, or 6,000 dollars.

Now watch what happens over the next month, because this is where MRR earns its keep. Suppose you add two new Basic customers (+100 dollars), customer B upgrades from Pro to a 300 dollar plan (+100 dollars of expansion), and customer D cancels (-50 dollars of churn). Your new MRR is 500 + 100 + 100 - 50 = 650 dollars, and your ARR is now 7,800 dollars. One number tells you the whole story of the month: who you won, who grew, and who you lost.

The moving parts: how MRR changes

MRR is not one lump; it is the result of several forces pulling in different directions each month. Breaking it into these pieces is what turns MRR from a vanity number into a management tool.

The single most important relationship here is between the things that add and the things that subtract. If your New plus Expansion MRR is bigger than your Contraction plus Churned MRR, you grow. If it is smaller, you shrink, even if you are signing plenty of new customers. The dream is what people call net negative churn: when expansion from your existing customers alone outweighs all your losses, so your revenue would grow even if you never signed another new customer. The thing eating away at the bottom of that table, churn, is important enough that I wrote a separate guide on what churn rate is.

MRR, ARR, and other revenue numbers

A common source of confusion is how MRR relates to plain old revenue, and the difference matters. Total revenue is every dollar that came in: subscriptions, setup fees, one-off services, everything. MRR is narrower and stricter, only the recurring subscription part, normalized monthly. That strictness is the point: by excluding one-time money, MRR gives you a clean, comparable, forward-looking number.

This is also why investors care so much about MRR and ARR rather than total revenue. A business doing 1 million dollars of revenue from one-time projects starts next year at zero again. A business doing 1 million dollars of ARR starts next year with that million already recurring, before it sells anything new. Predictable, recurring revenue is simply worth more, which is the deeper reason the subscription model is so attractive, a theme I cover in my guide on the cost to build a SaaS and whether the investment pays back.

Common mistakes that inflate MRR

Because MRR is the headline metric founders quote, it is also the one most often fudged, usually by accident. Here are the mistakes I see most.

• Counting one-time fees as recurring. A 2,000 dollar setup fee is real money, but it is not MRR, because it will not happen again next month. Folding it in makes your recurring base look bigger than it is.
• Counting bookings instead of recurring revenue. If a customer signs an annual deal, the MRR is the yearly value divided by 12, not the whole contract dropped into one month.
• Ignoring discounts. If a plan lists at 100 dollars but the customer has a permanent 50 percent discount, their MRR is 50 dollars, not 100. Use what they actually pay.
• Counting unpaid trials. A free trial is not revenue until it converts to a paying plan. Trial users are a pipeline, not MRR.
• Forgetting to subtract churn. The most flattering and most dangerous mistake: celebrating New MRR while quietly ignoring the customers leaving out the back. Always look at net MRR change, not just what you added.

The honest rule is simple: only money you can reasonably expect to see again next month belongs in MRR. Anything else inflates the number and fools the only person who really matters, you.

The bottom line

MRR is your predictable monthly subscription revenue, and ARR is that same figure projected across a year, almost always MRR times 12. Together they are the heartbeat of a subscription business: MRR for the month-to-month detail of who you won, grew, and lost, and ARR for the headline run rate. Keep them honest by counting only genuinely recurring money, breaking MRR into its moving parts, and always watching the net change rather than just the new sales. Get that right and these two numbers will tell you more about the health of your business than almost anything else.

If you are building or running a subscription product and want help making sense of these numbers, modelling how they would grow, or building the kind of dashboard that tracks them automatically, that is squarely the kind of work I do. Book a call and tell me where you are, or reach out through the contact form, and I will help you get a clear picture of your recurring revenue.