CJ Gustafson is the creator of Mostly Metrics, one of the most popular newsletters for SaaS finance, and the CFO of PartsTech. He is known for blending deep financial technicality with a witty, "non-boring" writing style.

Part 1: SaaS Metrics & Unit Economics

  1. On Gross Margin: "Gross margin is the ceiling of your potential. You can’t optimize your way out of a low-margin business."
  2. On Burn Rate: "Burn is the price you pay for the chance to be wrong. The more you burn, the less time you have to find the right answer."
  3. On Churn: "If you have a leaky bucket, pouring more water (CAC) into it isn't a strategy; it's a tragedy."
  4. On Net Revenue Retention (NRR): "NRR is the ultimate truth teller. It tells you if your customers actually like you after the honeymoon phase is over."
  5. On The Rule of 40: "The Rule of 40 is a balance scale. You can be a fast-growing fireball or a cash-generating machine, but you can’t be neither."
  6. On CAC Payback: "CAC Payback period is the 'Time to Breakeven' on a human relationship."
  7. On LTV: "Lifetime Value is often a 'Choose Your Own Adventure' novel written by an optimistic VP of Sales. Be careful with the assumptions."
  8. On Magic Number: "A Sales Magic Number over 1.0 means you have a green light. Under 0.5 means your engine is smoking."
  9. On Deferred Revenue: "Deferred revenue is a 'debt' you owe the customer in the form of service. It’s the best kind of debt because there’s no interest rate."
  10. On Professional Services: "Services revenue is the 'vegetables' of SaaS. You need them to grow big and strong, but investors only want to pay for the 'dessert' (software)."

Part 2: The CFO Role & Psychology

  1. On Saying No: "The CFO’s job isn’t to say 'No.' It’s to say 'Here is what happens if we say Yes.'"
  2. On Risk: "Finance isn't about avoiding risk; it's about pricing it correctly."
  3. On FP&A: "FP&A is 20% math and 80% communication. If people don't understand the model, the model doesn't exist."
  4. On the 'No-Surprises' Rule: "The worst thing a CFO can do is surprise the Board. Bad news delivered early is a problem; bad news delivered late is a crisis."
  5. On Data Quality: "Bad data is like a bad haircut. Everyone notices, and it takes a long time to grow out of it."
  6. On Budgeting: "A budget is a hallucination of how the next year will go. A forecast is the sober realization of how it’s actually going."
  7. On Variance: "Don't just tell me we missed the budget. Tell me why we missed it and what we’re doing so it doesn’t happen again."
  8. On Being a Business Partner: "To be a great CFO, you have to spend more time in Zoom rooms with the Head of Product than in Excel spreadsheets."
  9. On Simplicity: "If you can’t explain your business model to a 10-year-old, you probably don't understand it yourself."
  10. On Speed: "In a startup, 'perfect and late' is much worse than 'good and on time.'"

Part 3: Fundraising & Capital Allocation

  1. On Valuation: "Valuation is a moment in time; dilution is forever."
  2. On Raising Capital: "The best time to raise money is when you have plenty of it. Investors can smell desperation from a mile away."
  3. On Down Rounds: "A down round isn't the end of the world, but it is the end of the world as you knew it."
  4. On Runway: "Runway is a function of two things: the cash in the bank and the ego of the founders."
  5. On VCs: "Venture Capitalists are looking for 'outliers,' not 'averages.' Your job is to prove you are a freak of nature."
  6. On the 'Hype Cycle': "Don't mistake a tailwind for brilliance. When the wind stops blowing, we see who can actually row."
  7. On Capital Efficiency: "Capital efficiency is the ability to turn $1 of investor money into $5 of enterprise value."
  8. On Board Meetings: "The Board's job is to fire the CEO. Your job as CFO is to make sure they never have a reason to."
  9. On Options/Equity: "Employee options are a lottery ticket where you have to work 60 hours a week to increase the odds of winning."
  10. On Exit Strategy: "Companies are bought, not sold. Build a business so good they have to buy it."

Part 4: Career Advice & Leadership

  1. On Getting Promoted: "The best way to get promoted is to do the job of the person above you until it’s awkward that you don't have the title."
  2. On Writing: "Writing is the most underrated skill in finance. If you can write clearly, you can think clearly."
  3. On Networking: "Your network is your 'career insurance.' Pay the premiums before you need to file a claim."
  4. On Technical Skills: "Excel is the floor, not the ceiling. Learning SQL or Python is how you build the elevator."
  5. On Mentorship: "Find a mentor who will tell you your breath smells. You need the truth, not a pat on the back."
  6. On Hiring: "Hire for slope, not intercept. A hungry junior will outpace a lazy veteran every time."
  7. On Firing: "If you’re thinking about firing someone, you should have done it three months ago."
  8. On Soft Skills: "The higher you go in Finance, the less you use a calculator and the more you use a mirror."
  9. On Work-Life Balance: "Startups are a marathon, but they are composed of a thousand sprints. Don't forget to breathe."
  10. On Visibility: "Doing great work is 50% of the battle. Ensuring the right people know you did great work is the other 50%."

Part 5: General Business Wisdom

  1. On Competition: "Don't watch the competition so much that you forget to watch the customer."
  2. On Product-Market Fit: "PMF is when you stop pushing the product and the product starts pulling you."
  3. On Sales: "Sales solves all problems—until it creates 'bad' revenue that breaks the product."
  4. On Scaling: "Scaling is doing the things that worked at $1M ARR and realizing they are the exact things that will break at $10M ARR."
  5. On Inflation/Macro: "The macro environment is the weather. You can't change it, so you’d better buy an umbrella (cash reserves)."
  6. On Simplicity in SaaS: "The best SaaS products do one thing so well that the customer feels stupid for not paying for it."
  7. On Meetings: "A meeting without an agenda is just a play-date for adults."
  8. On Strategy: "Strategy is about deciding what not to do."
  9. On Accountability: "Accountability isn't about blame; it's about ownership. Own the miss, and you own the solution."
  10. On the Future of Finance: "The AI CFO won't replace the human CFO, but the CFO using AI will replace the one who isn't."

Part 6: The "2025 Playbook" & AI

  1. The Definitive 2025 Metric: "If I could only choose one metric to evaluate a company in 2025, I’d choose Revenue per Employee. Full stop. It cuts through all the noise.[1] There’s nowhere to hide." (Source: Maxio 2025 Metrics Report)
  2. AI Efficiency: "The real superpower of AI in finance isn't the chatbot; it's the 20% efficiency gain that lets you skip a venture round and keep your equity." (Source: Glasp Talk Episode #48)
  3. Internal vs. External AI: "Everyone is talking about how AI makes the product better. I want to talk about how AI makes the company cheaper to run." (Source: Mostly Metrics, "How CFOs are Actually Using AI")
  4. On BI and FP&A: "The days of exporting BI data into a spreadsheet are numbered. Finance now owns the data, not just the reporting."[2] (Source: Mostly Metrics, "10 Predictions for the Future of Finance")
  5. AI as a Headcount Tool: "AI won’t make your headcount zero, but it will make your headcount deadly efficient." (Source: Investing for Beginners Podcast)

Part 7: Advanced SaaS Mechanics (Vertical & Multi-Product)

  1. On Vertical SaaS: "In Vertical SaaS, you aren't selling a tool; you're selling the 'Control Point.' Once you own the workflow, you earn the right to sell the payments, the lending, and the payroll." (Source: Mostly Metrics, "The Top Metrics for Vertical SaaS")
  2. On Take Rate: "A 'Take Rate' is the most beautiful revenue because it grows with your customer’s success without you having to lift a finger." (Source: Substack, "A Guide to the Marketplace Plus Model")
  3. On Revenue Leakage: "Revenue leakage is a slow-motion car crash. Most CFOs don't realize they've hit the wall until the cash reconciliation doesn't match the billing system." (Source: Mostly Metrics, "Your Complete Guide to Revenue Leakage")
  4. On "Sales Rep Math": "Never trust a sales rep's forecast until you've applied 'Sales Rep Math'—which is the art of subtracting the 20% of deals that only exist in their imagination." (Source: Mostly Metrics, "The Importance of Sales Rep Math")
  5. On Pricing Evolution: "Software pricing has moved from 'Seats' to 'Value.' If you're still charging per login, you're inviting a competitor to eat your lunch." (Source: Mostly Metrics, "The Evolution of Software Pricing")

Part 8: The CFO as a Storyteller & "Adult in the Room"

  1. CFO as Portfolio Manager: "I view the CFO role as a Portfolio Manager for the company. My assets are the 85% of costs that walk on two legs." (Source: CFO Weekly Interview, Jan 2025)
  2. The "Chief Truth Teller": "Sometimes the CFO has to tell the CEO their baby is ugly. It’s the hardest part of the job, and the most necessary." (Source: Run the Numbers Podcast)
  3. On Investor Relations: "Numbers are just characters in a story. If you can’t tell the story, the characters are just standing around doing nothing." (Source: Investing for Beginners Podcast)
  4. The Goalie Metaphor: "Being a CFO is like being a goalie. No one notices the 50 saves you made, but everyone remembers the one goal you let in." (Source: Glasp Talk Episode #48)

Part 9: Career & The "Creator-CFO" Transition

  1. The Media Mullet: "I’m building a 'Media Mullet'—business in the front (data-driven finance advice), party in the back (humor and dog pics)." (Source: Growth in Reverse, Aug 2025)
  2. Personal Product-Market Fit: "Don’t just look for a job. Look for 'Personal Product-Market Fit.' What do you get energy from that the market is willing to pay for?" (Source: Run the Numbers, "From CFO to Founder")
  3. On Writing into the Abyss: "I wrote into the abyss for two years before anyone listened. Consistency is the only hack that actually works." (Source: "What Worked" Podcast, June 2025)
  4. On Equity Psychology: "During an exit, equity isn't math anymore—it's emotion. People are finally seeing the 'lottery ticket' turn into a house payment." (Source: "What Worked" Podcast, June 2025)

CJ Gustafson’s insights are primarily distributed through his newsletter and LinkedIn. You can find the original context for these quotes at the following links: