SaaS Finance Terms Every Founder Should Know

The predictable revenue your SaaS business earns every month from active subscriptions. MRR is the heartbeat of any subscription business — it tells you whether your revenue engine is growing, stalling, or shrinking. Investors use MRR trends as the primary signal of product-market fit.

MRR should be calculated from contracted recurring charges only. One-time fees, professional services revenue, and usage overages typically belong in separate line items so your core subscription health stays clean.

Your MRR multiplied by 12, representing the annualized value of recurring subscription revenue. ARR is the standard top-line metric for SaaS companies doing board reporting and fundraising. It smooths out monthly fluctuations and gives a clearer picture of business scale.

ARR becomes the primary reporting metric once you cross roughly $1M in recurring revenue. Below that, MRR is more useful because it surfaces growth trends faster at the monthly cadence where you can still act on them.

The percentage of customers or revenue lost during a given period. In SaaS, churn is the silent killer — even small monthly churn compounds into massive annual losses. A 3% monthly churn rate means you lose nearly a third of your customer base every year.

Always track both logo churn (customer count) and revenue churn (dollar value) separately. Losing ten $50/month customers hurts differently than losing one $500/month customer, and the response strategy is completely different.

The total cost of acquiring one new customer, including marketing spend, sales team costs, and related overhead. In SaaS, CAC determines whether your growth is sustainable or just expensive. High CAC is fine if LTV is proportionally high — the ratio is what matters.

Calculate CAC by channel to understand which acquisition strategies are efficient. Blended CAC across all channels can mask the fact that one channel is carrying the others, or that your best-performing channel is reaching saturation.

The total revenue you expect to earn from a customer over their entire relationship with your product. LTV accounts for monthly revenue and expected lifespan (the inverse of churn). It is the other half of the most important ratio in SaaS: LTV:CAC.

LTV calculations should use gross margin, not raw revenue. A customer paying $1,000/month with 80% gross margin has a very different true value than one paying $1,000/month with 40% margin, even though the subscription price is identical.

The ratio between customer lifetime value and customer acquisition cost. A healthy SaaS business targets an LTV:CAC ratio of 3:1 or higher, meaning every dollar spent acquiring a customer returns at least three dollars. Below 1:1, you are literally paying to lose money.

LTV:CAC is a lagging indicator — by the time it looks bad, the damage is already done. Track leading signals like payback period and early cohort retention to catch problems before they show up in your LTV:CAC ratio.

The percentage of recurring revenue retained from existing customers over a period, including expansion, contraction, and churn. An NRR above 100% means your existing customers are spending more over time — you are growing even without acquiring new customers.

Top-performing SaaS companies achieve NRR of 120%+. This means for every $100 of starting revenue from a cohort, they have $120 twelve months later from that same cohort — even after accounting for churned customers.

In SaaS, the quick ratio measures growth efficiency by dividing new MRR plus expansion MRR by churned MRR plus contraction MRR. A ratio above 4 indicates healthy, efficient growth. Unlike the accounting quick ratio, this is specific to subscription revenue dynamics.

A SaaS quick ratio of 4 means for every dollar of MRR you lose, you add four dollars. Below 2, growth feels like running on a treadmill — you are adding customers but barely outpacing the ones leaving.

Additional recurring revenue earned from existing customers through upsells, cross-sells, or plan upgrades. Expansion revenue is the most capital-efficient growth lever in SaaS because the customer is already acquired and onboarded. It is revenue without a corresponding CAC.

Track expansion MRR as a separate component of total MRR growth. Companies that drive significant expansion revenue can sustain growth even as new logo acquisition becomes more competitive and expensive.

The number of months it takes to recover the cost of acquiring a customer through their subscription payments. In SaaS, a payback period under 12 months is considered healthy. Beyond 18 months, growth becomes a cash flow challenge even if the unit economics work long-term.

Payback period is often more actionable than LTV:CAC because it directly impacts cash flow planning. A long payback period means you need more working capital to fund growth, even if each customer is ultimately profitable.

The rate at which your SaaS company spends cash each month, typically measured as net burn (total spend minus total revenue). For pre-profit SaaS companies, burn rate determines how aggressively you can invest in growth before needing to raise again or reach profitability.

In SaaS, acceptable burn rate depends on growth rate. The Rule of 40 suggests your growth rate plus profit margin should exceed 40%. A company burning cash at a high rate is fine if revenue growth is proportionally fast.

The number of months your SaaS company can continue operating at its current burn rate before running out of cash. Runway is the clock that governs every strategic decision — hiring plans, product roadmaps, and fundraising timelines all depend on how many months you have left.

SaaS founders should start fundraising with at least 6-9 months of runway remaining. The fundraising process typically takes 3-6 months, and investor conversations go better when you are negotiating from a position of time, not desperation.