Venture Capital & Startup Lab

SaaS Metrics & Rule of 40 Lab

Calculate Rule of 40, Burn Multiple, SaaS Magic Number, CAC payback period, and 12-month ARR runway trajectories.

SaaS Model 12-Month Runway SaaS Theory FAQ

Venture Presets

Load calibrated startup stages.

Step 1: ARR, Burn & Acquisition Inputs

SaaS Financial Parameters

1. ARR & Profitability

$
Current Annualized Recurring Revenue.
$
ARR 12 months ago.
%
Operating margin or cash flow margin.

2. Cash Burn & S&M Spend

$
Net cash consumed over last 12 months.
$
New logos + expansion − churn ARR.
$
Prior quarter sales/marketing spend.
$
Sequential GAAP quarterly revenue gain.

3. CAC Payback & Cash Bank

$
Fully loaded cost to acquire customer.
$
Average monthly revenue per account.
%
Hosting, support & direct margin.
$
Total cash in bank reserves.
Rule of 40
0.0%
Elite (>40%)
Burn Multiple
0.0x
Capital Efficient
SaaS Magic Number
0.00
ARR Growth Pace
+0.0% YoY
CAC Payback
0.0 Months
Cash Runway
0.0 Mos

Step 2: 12-Month Scaling & Runway Trajectory

Projected ARR Expansion & Cash Burn Schedule

Projects forward ARR expansion, monthly cash depletion, and remaining months of runway based on current capital consumption.

Timeline Milestone Projected ARR ($) Cash Reserve Balance ($) Remaining Runway

Venture Capital Guide

Understanding SaaS capital efficiency

Investors and boards evaluate recurring revenue companies not only on top-line growth, but on the capital cost required to achieve that growth.

  • Rule of 40 Balance: A business growing 60% with a -20% margin scores 40%; a mature business growing 20% with a +20% margin also scores 40%. Both represent strong capital allocation.
  • The Burn Multiple: Popularized by Craft Ventures, a Burn Multiple < 1.0x indicates you generate more than $1 of net new ARR for every $1 burned.
  • Magic Number Hurdle: A score > 1.0 means customer acquisition is so efficient that the company should accelerate sales and marketing hiring immediately.

Analyze unit economics in the Unit Economics Lab.

SaaS Equations

Essential SaaS formulas

Rule of 40 (%) = ARR Growth Rate (%) + Free Cash Flow Margin (%)

Burn Multiple = Net Cash Burned ÷ Net New ARR Added

SaaS Magic Number = (Net New Q Rev × 4) ÷ S&M Expense

CAC Payback (Months) = CAC ÷ (Monthly ARPU × Gross Margin %)

Runway (Months) = Cash Reserve ÷ (Annual Cash Burn ÷ 12)

Model churn decay in the Customer Churn Lab.

FAQ

SaaS metrics and venture capital questions

What is the SaaS Rule of 40 and why does it matter?

The Rule of 40 states that a healthy software company's annual revenue growth rate plus its free cash flow (or operating) margin should equal or exceed 40%, balancing aggressive expansion with financial sustainability.

What is the Burn Multiple and how is it evaluated?

Burn Multiple measures capital efficiency: Net Cash Burned ÷ Net New ARR Added. A multiple under 1.0x is exceptional, 1.0x–1.5x is good, and above 2.0x indicates inefficient growth requiring excessive dilutive capital.

How is the SaaS Magic Number calculated?

The Magic Number evaluates sales and marketing efficiency: (Net New Quarterly GAAP Revenue × 4) ÷ Prior Quarter Sales & Marketing Expense. A score above 1.0 indicates strong sales efficiency.

How do you calculate CAC Payback Period?

CAC Payback (Months) = Average Customer Acquisition Cost ÷ (Monthly ARPU × Gross Margin %). It measures the exact number of months required for a customer to pay back their acquisition cost.

Can I export SaaS efficiency benchmarks to CSV?

Yes. You can export complete Rule of 40 scores, Burn Multiples, Magic Numbers, CAC paybacks, and 12-month cash runway schedules as a UTF-8 CSV spreadsheet with formula injection defense or print an executive brief.

Is this tool certified venture capital auditing or investment banking advice?

No. This tool provides simplified educational SaaS financial models for business training without certified venture capital underwriting, formal valuation opinions, or fiduciary advice.

Continue Exploring Growth & Finance Tools

Explore our Resilience Simulation Hub, analyze customer retention in the Customer Churn Lab, value companies in the Business Valuation Lab, or calculate ROAS in the Marketing ROAS Lab.