SaaS Stocks: 8 Key Metrics Every Investor Must Monitor

If you’re investing in software companies without understanding SaaS-specific metrics, you’re reading a nutrition label while ignoring the ingredients. The financial statements tell one story—the operational metrics tell another. In SaaS, the operational story often predicts the financial future better than past performance ever could.

The challenge is that most investors outside the industry have never encountered concepts like Net Revenue Retention or the Rule of 40. These aren’t accounting gimmicks—they’re diagnostic tools that reveal whether a SaaS company is building sustainable value or burning through investor capital while acquiring customers it can never retain. I’ve spent over a decade analyzing software companies, and the difference between a profitable SaaS investment and a disaster often comes down to understanding these eight metrics—and knowing which ones matter more at different growth stages.

Monthly Recurring Revenue (MRR)

MRR represents the predictable revenue a company expects to collect each month from its subscription base. It’s the foundation of how SaaS businesses are valued, and ignoring it is like evaluating a retailer without looking at sales.

The calculation is straightforward: take all active subscription revenue, normalize it to a monthly figure (annual contracts divided by 12), and add recurring add-ons or usage-based revenue. But here’s what many investors miss—MRR isn’t just a vanity number. The way it grows month-over-month tells you whether the business is accelerating, decelerating, or stuck in a plateau.

Datadog’s Q3 2024 earnings showed MRR of $734 million, representing 27% year-over-year growth. That figure alone doesn’t tell the full story, but when you layer in the trajectory—the fact that their growth rate has remained above 25% while scaling to this size—it’s remarkable. Compare that to some IPO-era SaaS companies that were growing 100% annually at $50 million in ARR but decelerated to 20% by the time they reached $500 million. The MRR growth curve reveals that deceleration pattern long before it shows up in stock price.

What matters for investors: look for consistent MRR growth that doesn’t require exponentially higher spending. A company growing MRR 30% year-over-year while doubling its sales budget is executing differently than one growing 30% with flat marketing spend. The efficiency story lives in the ratio of growth to investment.

Annual Recurring Revenue (ARR)

If MRR is the heartbeat, ARR is the yearly EKG—it shows the same vital signs but over a longer timeframe that makes patterns easier to spot. Most public SaaS companies report ARR in their quarterly releases because it smooths out the monthly noise and gives investors a cleaner view of the underlying business momentum.

For early-stage private companies, ARR often serves as the primary metric because monthly figures can be volatile. A single large contract signing or renewal can swing MRR meaningfully, but ARR normalizes that over 12 months.

Salesforce reported $35.9 billion in FY2024 revenue. While not labeled as ARR in their public filings, this represents the annualized value of their subscription and services business. The distinction matters here—Salesforce is large enough that they’re often evaluated on traditional metrics like revenue growth and operating margin, but investors tracking their evolution from a CRM pure-play to an enterprise platform still watch the ARR trajectory to understand which new product lines are gaining traction.

The practical takeaway: use ARR to compare companies of similar scale and to track multi-year growth trajectories. A company going from $100 million to $200 million ARR (100% growth) is executing differently than one going from $1 billion to $1.3 billion (30% growth), even though both are “growing.” The relative context matters more than the absolute number.

Net Revenue Retention (NRR)

This is the metric that separates good SaaS companies from great ones, and it’s the one I see investors underweight most often. NRR measures the revenue you’re getting from existing customers compared to what you got from them a year ago—including expansion revenue, downgrades, and cancellations.

A NRR above 100% means your existing customer base is growing your revenue even without adding new customers. That’s the compounding magic that makes SaaS businesses valuable. You’re not just replacing churned revenue—you’re growing the wallet share of customers who already trust you.

Snowflake reported NRR of 134% as of their most recent quarterly filing. That means their average customer was spending 34% more than they were a year ago. That’s extraordinary. It tells you their product is expanding use cases within existing accounts, that customers are seeing enough value to pay more, and that churn isn’t eating their growth.

The benchmark you need to know: above 100% is excellent. 110-120% is strong. Above 120% puts you in the top tier with companies like Snowflake, Datadog, and HubSpot. Below 100% means you’re losing money from your existing base every year—and you need to acquire that much more new revenue just to stand still.

Here’s the counterintuitive part that many articles ignore: NRR above 130% isn’t always better. At extremely high NRR levels, you have to ask whether the expansion is sustainable or whether you’re extracting too much from a shrinking customer base. Companies with 150%+ NRR often have concentration risk—their expansion is coming from a small subset of customers, and if those accounts stall, the overall number drops fast. Look at the composition: is the expansion broad-based or concentrated?

Customer Churn Rate

Churn is the enemy. It measures the percentage of customers or revenue you lose in a given period, and in SaaS, it compounds ruthlessly. Lose 5% of customers monthly, and you’ll have roughly half your customer base left in a year.

There are two types of churn to track: customer churn (logo loss) and revenue churn (dollar loss). A company can have low customer churn but high revenue churn if it’s losing its largest accounts. Conversely, a company losing small customers might show high customer churn percentage-wise but low revenue impact.

Zendesk’s historical data is instructive here. In their growth phase, they targeted SMBs where churn naturally runs higher—often 5-10% monthly for companies without enterprise-level retention infrastructure. As they shifted toward enterprise, their churn metrics improved meaningfully. The lesson: churn benchmarks vary by market segment. Enterprise SaaS companies should target under 1% monthly customer churn. Mid-market, 1-3%. SMB-focused, 3-5% is often acceptable if CAC is low enough to justify the shorter customer lifespan.

The metric I prefer to track alongside raw churn: churned ARR. Instead of just knowing you lost 3% of customers, know that those customers represented $2 million in annual revenue. That context changes how you evaluate the severity of your retention problem.

Customer Acquisition Cost (CAC) and CAC Payback Period

CAC tells you how much it costs to acquire a new customer. The formula is simple—total sales and marketing spend divided by the number of new customers acquired—but the interpretation gets nuanced.

What’s a “good” CAC? It depends entirely on what you’re paying back. This is where CAC payback period becomes essential. Payback period measures how long it takes for a customer to generate enough gross profit to cover their acquisition cost. Shorter is better.

If your CAC is $1,000 and customers pay you $100/month with 80% gross margins, you earn $80/month in gross profit from each customer. Your payback period is 12.5 months—$1,000 divided by $80. That’s solid. If your payback stretches to 24 months, you’re running a capital-intensive business that requires constant funding to grow.

The rule of thumb: SaaS companies with payback periods under 12 months are operating efficiently. Under 6 months is exceptional. Above 18 months should make you skeptical unless there’s a strategic reason (like intentionally sacrificing short-term economics for market share).

HubSpot has historically operated with CAC payback in the 12-14 month range, which is healthy for a mid-market B2B SaaS company. They’ve been able to scale efficiently because their inbound marketing model generates leads at lower cost than outbound sales teams—a structural advantage that’s reflected in their economics.

Watch for this red flag: companies that report “blended” CAC combining new customer acquisition with upselling to existing customers. That’s misleading. Expansion CAC is often a fraction of new customer CAC, and blending them together makes acquisition look cheaper than it actually is.

Customer Lifetime Value (LTV)

LTV predicts the total revenue you’ll earn from a customer over the entire relationship. In SaaS, the formula typically multiplies average revenue per account by average customer lifespan (1 divided by annual churn rate).

A company with $10,000 average ACV and 10% annual churn has an expected LTV of $100,000. That’s a 10-year customer lifetime. If that same company has 50% annual churn (2-year lifetime), LTV drops to $20,000.

The LTV-to-CAC ratio is one of the most important efficiency metrics in SaaS. A ratio of 3:1 or higher is generally considered healthy—it means for every dollar spent acquiring a customer, you’re earning three dollars back over their lifetime. Below 2:1 and you’re probably not building a sustainable business.

But here’s the limitation most articles won’t mention: LTV calculations are notoriously sensitive to assumptions. Change your churn estimate by two percentage points, and LTV swings by 20% or more. Companies can make their unit economics look better by assuming lower churn. Always sanity-check LTV against actual historical retention. If a company claims 5-year customer lifespans but has only been selling for three years, that’s a projection, not a fact.

Intuit’s SaaS properties (QuickBooks Online, Mailchimp) have demonstrated strong LTV characteristics because they serve small businesses that grow into larger ones over time—the product becomes embedded in their customers’ operations, making switching costs high and churn low.

Rule of 40

The Rule of 40 states that a SaaS company’s revenue growth rate plus its profit margin should exceed 40%. Brad Feld popularized it in 2015, and it’s become one of the most cited metrics for evaluating SaaS businesses—especially for investors who want to assess the balance between growth and profitability.

The logic is elegant: if you’re growing 50% annually, you can afford to be unprofitable (or even losing money) as long as the sum of your growth rate and profit margin exceeds 40%. If you’re growing 20%, you need 20%+ profit margins to meet the threshold. Growth and profitability trade off against each other in this framework.

As of late 2024, the Rule of 40 has become harder to achieve. Higher interest rates have compressed valuations, and public market investors now demand more proof of path to profitability. Companies that were celebrated for 60% growth at 15% losses (Rule of 40: 45) are now being penalized because the market discounts future cash flows more heavily.

Adobe’s transformation is instructive here. When they shifted from perpetual licensing to subscription, their growth rate initially dipped while profit margins improved. Investors had to recalibrate—the Rule of 40 doesn’t apply identically to companies at different stages. Adobe’s transition to SaaS eventually produced growth-profitability combinations that exceeded the threshold consistently.

My honest take: the Rule of 40 is useful but imperfect. It works best for companies between $50 million and $500 million in ARR. Below that scale, hypergrowth often justifies losses. Above that scale, mature companies should be profitable. Don’t use the same threshold for a $100 million ARR company and a $2 billion ARR company—the dynamics are fundamentally different.

Burn Rate and Runway

For pre-profitability SaaS companies, burn rate and runway determine how much time you have to execute before needing more capital. Burn rate is simply how much cash you’re losing each month. Runway is how many months of cash you have left at current burn levels.

This matters more now than it has in years. The venture capital environment shifted meaningfully in 2022-2023, and companies that were burning aggressively to chase growth at all costs found themselves in difficult positions when fundraising windows closed. Runway became a strategic concern, not just a financial metric.

Atlassian’s path is worth studying here. For years they operated with minimal burn relative to their growth, which gave them flexibility to invest during downturns while competitors were cutting. Their ability to remain cash-flow positive even as they scaled meant they weren’t dependent on external capital—a position of strength that manifested in their ability to acquire companies like Trello and Loom during periods when other buyers were retreating.

What to watch: runway isn’t just about having cash in the bank. It’s about having options. A company with 24 months of runway but a board mandate to reach profitability in 18 months isn’t really free to spend. Look at the trajectory, not just the current balance. If burn is increasing while revenue growth is decelerating, runway is shrinking faster than the headline number suggests.

Conclusion

These eight metrics—MRR, ARR, NRR, churn, CAC with payback period, LTV, Rule of 40, and burn rate with runway—form the diagnostic framework you need to evaluate any SaaS investment. They’re not the only factors worth considering (governance, TAM, competitive positioning, management execution all matter), but they’re the operational metrics that reveal whether the business model actually works.

The investors who get burned in SaaS are usually the ones who fall in love with growth headlines while ignoring the efficiency underneath. A company growing 50% annually but burning $50 million a year is making a very different bet than one growing 30% and generating free cash flow. Both can be good investments—but you need to understand which bet you’re making.

Here’s what remains genuinely unresolved in SaaS investing: how to value companies that achieve Rule of 40 consistently but trade at vastly different multiples. Two companies with identical efficiency metrics can trade at 10x revenue or 30x revenue. The market clearly prices something beyond these operational metrics—brand strength, ecosystem lock-in, management credibility—but quantifying that premium consistently remains more art than science.

Use these metrics to eliminate companies that have fundamental business model problems. Then trust your broader investment judgment for the rest.