Ask five SaaS founders which metrics matter most and you’ll likely get five different answers — and a little bit of anxiety along with them. The truth is that most SaaS businesses are ultimately judged on a fairly consistent set of numbers, whether by investors evaluating a term sheet, a board reviewing quarterly performance, or a founder’s own finance function trying to make sense of the business day to day. Here’s a plain-English tour of the ones worth knowing cold, along with why each one tends to matter.
Revenue and Growth
These are usually the first numbers anyone asks about, and for good reason — they establish the size and trajectory of the business before anything else gets discussed.
- MRR/ARR (Monthly/Annual Recurring Revenue) — the predictable revenue baseline your business runs on, and the figure most commonly quoted externally.
- Growth rate — typically measured month-over-month or year-over-year, often segmented between new customer revenue and expansion revenue from existing customers.
- New vs. expansion revenue mix — a useful way to see whether growth is coming primarily from new logos or from your existing base, since the two usually require very different go-to-market investments.
Retention and Efficiency
Growth alone doesn’t tell you much without knowing whether it’s efficient or whether it’s sticking. This is where these metrics come in.
- Churn rate — the percentage of customers or revenue lost over a period; customer churn and revenue churn are worth watching separately, since losing a few small accounts looks very different from losing one large one.
- Net Revenue Retention (NRR) — measures whether your existing customer base is growing or shrinking in revenue terms once upsells, downgrades, and cancellations are all netted together.
- CAC (Customer Acquisition Cost) and LTV (Lifetime Value) — together, these help you understand whether your growth is efficient or expensive, and whether your current go-to-market motion is sustainable at scale.
- Rule of 40 — a rough rule of thumb combining growth rate and profit margin, often used as a quick health check by investors comparing companies at different stages of maturity.
- Payback period — roughly how long it takes to recover the cost of acquiring a customer through the revenue that customer generates.
Cash and Runway
Ultimately, growth and retention metrics matter because they feed into the question every founder eventually has to answer: how long does the company have before it needs more capital, and on what terms.
- Gross burn and net burn — how much cash you’re spending, and how much you’re spending after accounting for revenue coming in.
- Runway — how many months of operation your current cash balance supports at your current burn rate, often modeled under a few different growth scenarios.
- Burn multiple — net burn divided by net new recurring revenue, a metric increasingly used by investors to assess capital efficiency independent of company size.
How These Metrics Work Together
No single metric tells the whole story on its own — a strong growth rate paired with high churn can be just as concerning to an experienced investor as slow growth paired with excellent retention, because both scenarios raise real questions about the durability of the business. The most useful way to look at these numbers is usually as a set, checking whether they tell a consistent story about the health of the business rather than picking out the one or two that happen to look best in a given quarter.
For MedTech and cybersecurity SaaS companies in particular, it’s often worth interpreting these metrics with some added context — longer sales cycles can make growth rate look slower in the short term even when pipeline health is strong, and regulatory or compliance-driven customer relationships can produce unusually low churn that reflects switching costs as much as satisfaction.
How Often to Review These Numbers
Cadence matters almost as much as the metrics themselves. Reviewing this full set monthly, alongside your cash position, tends to give founders enough resolution to catch problems early without turning every week into a metrics exercise. Board and investor updates typically want the same core numbers, presented consistently period over period, so that trends — not just single-period snapshots — are easy to see.
It’s also worth deciding in advance which metrics get reported externally versus which are primarily for internal use. Some efficiency metrics, like burn multiple or payback period, are often more useful as internal diagnostic tools than as headline numbers shared broadly, since they can be sensitive to short-term timing in ways that require context to interpret correctly.
Sales and Marketing Efficiency
Alongside the core revenue, retention, and cash metrics, most SaaS finance functions also keep an eye on a smaller set of go-to-market efficiency numbers, since they explain why CAC and growth rate are moving the way they are.
- Magic Number — a rough measure of sales efficiency comparing new recurring revenue generated to sales and marketing spend in the prior period.
- Sales cycle length — how long it typically takes to close a new customer, which tends to run longer in cybersecurity and MedTech than in more transactional SaaS categories.
- Win rate — the percentage of qualified opportunities that convert to closed deals, useful for spotting changes in competitive position or lead quality.
Common Pitfalls When Tracking These Metrics
A few mistakes come up often enough among early-stage SaaS companies that they’re worth flagging directly.
- Defining metrics inconsistently over time — for example, changing what counts as an active customer or a churned account without noting the change — which makes trend lines misleading even when each individual number is technically accurate.
- Comparing your numbers to published benchmarks without adjusting for company stage, sales motion, or industry, since a benchmark built from consumer SaaS companies may not translate well to enterprise MedTech or cybersecurity sales cycles.
- Optimizing a single metric in isolation — for instance, driving churn down aggressively through discounting in a way that quietly damages CAC payback or overall unit economics.
- Waiting until a fundraise or board meeting to calculate these metrics for the first time, rather than tracking them consistently enough that the numbers are already trusted and well understood before anyone outside the company asks for them.
Where to Start If You’re Not Tracking These Yet
If your company isn’t yet tracking most of these metrics in a consistent way, it’s rarely useful to try to stand up all of them at once. A more practical starting point is usually MRR/ARR, gross churn, and runway, since those three give a reasonably complete picture of growth, retention, and cash with a relatively small amount of setup work. From there, NRR and CAC/LTV are often the next additions, once the underlying customer and cost data needed to calculate them reliably is in place.
It’s also worth deciding early who owns each number and where it lives — whether that’s a finance team member, a fractional CFO, or a shared spreadsheet reviewed monthly — so that the metrics stay current and consistent rather than becoming a one-time exercise ahead of a fundraise.
No single metric tells the whole story on its own, and the goal isn’t to optimize any one number in isolation — it’s to understand how they move together and what that combination is telling you about the underlying health of the business. Over the next several posts, we’ll go deeper on several of these metrics individually, including how they tend to be interpreted differently across cybersecurity and MedTech SaaS businesses specifically including how they tend to be interpreted differently across cybersecurity and MedTech SaaS businesses specifically.
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About Herod CPA PLLC
Herod CPA PLLC provides forecasting, budgeting, and financial modeling services to SaaS startups within the cybersecurity and MedTech sectors.
Contact us at info@herod.cpa or follow us on LinkedIn for more information.