Why three numbers tell the whole SaaS story
SaaS businesses are deceptively simple at the financial level. You have a monthly recurring revenue number, a churn rate that steadily erodes it, and the relationship between those two numbers determines whether you grow, plateau, or decline. Every other metric — ARR, LTV, payback period, growth rate — is derived from these inputs. The challenge is that most founders track MRR and churn separately and never see the compound effect of churn on their revenue trajectory.
This calculator takes just two inputs — your current Monthly Recurring Revenue and your monthly churn rate — and produces three outputs that give you an instant snapshot of subscription health. ARR (Annual Run Rate) is MRR multiplied by 12, giving you a number that investors and benchmarking tools use universally. Approximate LTV is MRR divided by churn rate, telling you the total revenue value of your current book of business. The 12-month projection shows what happens to your MRR if you acquire zero new customers — a sobering view of churn's compounding effect.
The declining MRR projection is not a forecast of your actual future. It is a diagnostic tool. If your 12-month projection shows MRR dropping by 40%, it means you need to acquire enough new MRR each month just to offset churn before you can grow. This is the 'churn treadmill' that many early-stage SaaS companies underestimate.
SaaS health benchmarks by company stage
| Metric | Early Stage | Growth Stage | Mature | Enterprise |
|---|---|---|---|---|
| Monthly churn | 3 - 5% | 2 - 3% | 1 - 2% | Under 1% |
| MoM MRR growth | 10 - 20% | 5 - 10% | 2 - 5% | 1 - 3% |
| Rule of 40 | N/A | 40%+ | 40%+ | 40%+ |
| Net dollar retention | 80 - 100% | 100 - 120% | 110 - 130% | 120%+ |
| LTV:CAC ratio | 1 - 3:1 | 3 - 5:1 | 3 - 5:1 | 5:1+ |
How to get your SaaS metrics snapshot
Enter your current Monthly Recurring Revenue — sum of all active subscription revenue for the current month
Set your monthly churn rate as a percentage — the fraction of MRR lost to cancellations and downgrades each month
Read your ARR — this is MRR times 12, a run-rate number used for valuation and benchmarking
Read your approximate LTV — this is MRR divided by churn rate, representing the total value of your current revenue stream if churn stays constant
Review the 12-month MRR projection — this shows the compound erosion of MRR with zero new sales, illustrating how much new MRR you must add each month just to stay flat
Testing SaaS metrics with real numbers
Test a growth-stage SaaS company: $80,000 MRR with 3% monthly churn. ARR is $960,000. Approximate LTV is $80,000 divided by 0.03, which is roughly $2.67 million. The 12-month projection shows MRR declining to about $55,600 — a 30% drop — if no new customers are added. This means the company needs to add roughly $2,000 in new MRR each month just to break even, and significantly more to grow.
Now test the impact of churn reduction: same $80,000 MRR but churn improves to 2%. LTV jumps to $4 million. The 12-month projection shows MRR at about $63,200 — only a 21% decline. The difference between 3% and 2% churn is roughly $1.3 million in LTV and a meaningful reduction in the new MRR needed each month. This is why churn reduction is often the highest-ROI initiative for growth-stage SaaS companies.
Test an enterprise SaaS company: $500,000 MRR with 0.8% monthly churn. ARR is $6 million. LTV is $62.5 million. The 12-month projection shows MRR declining only about 9% without new sales. Low churn means the company has enormous breathing room — even a bad quarter of sales will not catastrophically impact revenue.
Common SaaS metrics mistakes
Confusing ARR with actual annual revenue — ARR is a run-rate (MRR times 12), not a forecast; actual revenue includes non-recurring items, expansions, and contractions that ARR does not capture
Using the LTV approximation for per-customer decisions — MRR divided by churn gives aggregate LTV, not per-customer LTV; for customer-level economics, use a dedicated CLV Calculator
Ignoring the 12-month projection — if you only look at ARR and LTV, you miss the churn treadmill effect that tells you how much new MRR you need to sustain growth
Mixing gross and net churn — gross churn measures only losses; net churn includes expansion revenue and can mask underlying retention problems if expansion is strong
Comparing ARR across companies with different revenue recognition policies — some companies book annual contracts upfront while others recognize monthly
Understanding the projection and its assumptions
The 12-month MRR projection assumes a constant monthly churn rate applied to the declining MRR balance. In reality, churn is not perfectly uniform — some months are higher (end of contract terms, seasonal patterns) and some are lower. The projection also does not account for expansion revenue from existing customers upgrading their plans. A company with strong expansion might see net MRR stay flat or even grow despite gross churn, because upsells and upgrades offset the losses.
The LTV approximation (MRR divided by churn) is a steady-state formula that assumes all customers have the same revenue and the same churn probability. In practice, enterprise customers have lower churn and higher ARPU than SMB customers, so your true LTV is a blend of these segments. For more precise per-segment analysis, calculate LTV separately for each customer tier. This calculator gives you the aggregate picture quickly — the segmented analysis is the next step.
The Rule of 40 — the principle that your growth rate plus your profit margin should exceed 40% — is a useful check on whether your ARR and growth trajectory are healthy. If your ARR is $1 million and growing 60% year over year, the Rule of 40 says you can afford to be unprofitable (the growth more than compensates). If growth slows to 15%, you need at least 25% margins to satisfy investors.
Who uses a SaaS metrics calculator
SaaS founders preparing board updates who need ARR, LTV, and churn impact in a single view
CFOs and finance teams building monthly reporting dashboards and investor communication materials
Operators evaluating whether churn reduction or new sales acceleration should be the priority
Investors performing quick due diligence on SaaS companies during initial screening
RevOps teams setting monthly new MRR targets based on churn offset requirements
Frequently asked questions
Q: What is the LTV approximation used here?
A: LTV approximately equals MRR divided by monthly churn rate. At $50,000 MRR with 5% churn, LTV is approximately $1 million. This is a steady-state aggregate approximation.
Q: Why does the 12-month projection show declining MRR?
A: The projection assumes zero new sales. Without new customer acquisition, churn erodes MRR each month. This shows the minimum new MRR you need to add just to maintain current levels.
Q: What is the relationship between ARR and MRR?
A: ARR equals MRR multiplied by 12. It is a run-rate figure used for valuation and benchmarking, not a fiscal-year revenue forecast.
Q: What is a good churn rate for SaaS?
A: SMB SaaS typically sees 3-5% monthly churn. Mid-market is 1-2%. Enterprise is under 1%. Lower churn directly translates to higher LTV and more capital-efficient growth.
Q: Is my data uploaded?
A: No — all math runs locally in your browser.
Q: How does this relate to the Rule of 40?
A: The Rule of 40 states that growth rate plus profit margin should exceed 40%. Use your ARR growth rate from this calculator alongside your margin to check compliance.
Get your SaaS metrics snapshot
See your ARR, LTV, and churn impact with the SaaS Metrics Calculator. Track your monthly revenue movements with the MRR Calculator. Calculate per-customer value with the CLV Calculator. Monitor retention with the Churn Rate Calculator or evaluate per-user monetization with the ARPU Calculator.
