MRR vs ARR vs ARPU: A Plain-English Metrics Glossary

Three acronyms show up in every SaaS thread — MRR, ARR, and ARPU — and they get used almost interchangeably by people who should know better. They measure related but different things, and using the wrong one makes your business look better or worse than it is. Here is each one, in plain English, with the formula and a worked example.

MRR — Monthly Recurring Revenue

MRR is the total predictable revenue from your subscriptions, normalized to one month. Annual plans are divided by 12, monthly plans counted as-is, everything summed. It is the working metric of most indie SaaS because the monthly cadence matches how you actually experience the business: signups, cancellations, and card charges mostly happen on a monthly rhythm.

Example: 100 customers paying $12/month = $1,200 MRR. Add 20 customers on a $120 annual plan and you add 20 x ($120 / 12) = $200, for $1,400 MRR total.

ARR — Annual Recurring Revenue

ARR is simply MRR multiplied by 12. It is the same underlying reality expressed on a yearly scale. ARR is popular with investors and larger companies because annual figures feel weightier and map to fiscal-year planning. For a maker doing $1,400 MRR, ARR is $16,800.

The trap with ARR is that it annualizes a single moment. If your MRR is volatile or you just landed one big customer, multiplying by 12 projects a full year of stability you have not earned yet. For an early-stage indie product with churn still bouncing around, MRR is the more honest lens; ARR is best used once your recurring base is genuinely stable.

ARPU — Average Revenue Per User

ARPU tells you how much each customer is worth on average. The formula is MRR divided by the number of active customers (some people use ARPA — per account — when one account has many seats). With $1,400 MRR across 120 customers, ARPU is about $11.67 per month.

ARPU is the metric that reveals pricing health. Rising ARPU means you are attracting higher-value customers, upselling successfully, or trimming the cheap tier — all good signs. Falling ARPU can mean a discount is dragging you down, or that growth is concentrated in your lowest plan, which quietly raises your support load without raising revenue.

• MRR = sum of monthly-normalized subscription revenue.
• ARR = MRR x 12.
• ARPU = MRR / active customers.
• Use MRR for day-to-day operating; ARR for annual planning and investor talk; ARPU to judge pricing and customer mix.

Which one should you watch?

As an indie maker, run your business on MRR and check ARPU monthly to catch pricing drift. Reach for ARR only when you need a big, stable headline number — a milestone post, a valuation conversation, or a yearly review. Watching all three together is more useful than any one alone: MRR shows scale, ARPU shows quality, and ARR shows the annualized stakes.