Financial modeling bootcamp for building quick-and-dirty models in real time. Use the decision tree to pick a model type, then expand the industry for formulas, inputs, and metrics.
quick decision tree — 4 questions17 industries — click any to expand

Dog #1 says: "Retail is simple until you count inventory twice. Same-store sales growth is the number that actually matters — everything else is noise."
Retail models live and die by traffic × conversion × basket size. The key insight is separating growth from existing stores (comparable sales) versus new store openings — a 10% revenue increase looks very different if it's all new locations burning cash vs. existing stores improving productivity.
Revenue = Stores × Avg Revenue/Store
Same-Store Sales Growth = (Rev_t − Rev_t-1) / Rev_t-1 [same cohort]
Gross Margin = Revenue − COGS (incl. shrink + inbound freight)
EBITDA = Gross Margin − Opex (occupancy + labor + marketing)

Dog #2 says: "RevPAR is the heartbeat of a hotel model. If RevPAR is growing, everything else can be fixed. If RevPAR is declining, no cost cut saves you."
Hotel models center on rooms as the fixed-cost base and revenue per available room (RevPAR) as the top-line driver. Once you've paid for the building, the marginal cost of filling a room is tiny — so occupancy rate swings dramatically impact profitability.
RevPAR = Occupancy Rate × Average Daily Rate (ADR)
Revenue = Available Rooms × RevPAR × 365
GOP Margin = (Revenue − Dept. Expenses) / Revenue
NOI = GOP − Fixed Charges (mgmt fees, insurance, taxes)

Dog #3 says: "Restaurant economics are brutal. The four-wall EBITDA is your only real signal — strip out corporate overhead and see if the actual restaurant makes money."
Restaurant models are unit economics at heart. Build one store P&L perfectly, then layer in new unit opening timelines. Prime costs (food + labor) as a combined percentage is the survival metric — it needs to stay below 65% to leave room for occupancy and overhead.
AUV = Covers × Average Check × Operating Days
Prime Cost % = (Food Cost + Labor Cost) / Revenue
4-Wall EBITDA = Revenue − Food − Labor − Occupancy − Other OpEx
System Revenue = AUV × Number of Units

Dog #4 says: "SaaS models are ARR waterfall models. New ARR − Churned ARR = Net New ARR. Simple. Until your churn cohorts mature and you realize your retention is terrible."
SaaS models are driven by the ARR waterfall: opening ARR + new bookings + expansion − contraction − churn = ending ARR. The unit economics (LTV / CAC) determine whether it's worth spending on growth. Rule of 40 is the summary metric that tells investors whether growth + profitability balance.
Net New ARR = New ARR + Expansion ARR − Contraction ARR − Churned ARR
NRR = (Beginning ARR + Expansion − Contraction − Churn) / Beginning ARR
CAC Payback = CAC / (ACV × Gross Margin %)
Rule of 40 = Revenue Growth % + FCF Margin %

Dog #5 says: "Capacity utilization is everything. A plant running at 60% is burning cash. The same plant at 85% prints money. That's the non-linearity of manufacturing."
Manufacturing models start with volume × price, then build COGS from the ground up: raw materials + direct labor + overhead absorption. Fixed overhead gets allocated to units — so volume swings create enormous margin volatility even if prices hold steady. A 10% volume drop can cut gross margin in half.
Revenue = Volume (units) × Average Selling Price
COGS = Variable Cost/Unit × Volume + Fixed Overhead
OH Absorption Variance = (Actual Vol − Budget Vol) × Std OH Rate/Unit
EBITDA = Revenue − COGS − SG&A
ROCE = EBIT / Capital Employed

Dog #6 says: "Banks are not normal companies. Revenue is net interest income — a spread. The model inverts: assets generate revenue, liabilities fund them. Get the balance sheet right first."
Banking models start with the balance sheet, not the income statement. Loans and investments earn interest (assets); deposits and debt cost interest (liabilities) — the spread is NIM. Add fee income, subtract credit losses and operating expenses, apply tax. Every assumption has a regulatory constraint attached.
NII = Interest Income (loans × yield) − Interest Expense (deposits × cost)
NIM = NII / Average Earning Assets
PPNR = NII + Non-Interest Income − Non-Interest Expense
Net Income = PPNR − Provision for Loan Losses − Taxes
CET1 Ratio = Common Equity Tier 1 / Risk-Weighted Assets

Dog #1 says: "Healthcare models are payor mix models in disguise. Medicare pays 80 cents on the dollar, Medicaid pays 60, commercial pays 110. Who's in your waiting room determines your margin."
Hospital models build revenue from patient volume × payor mix × reimbursement rates. Gross charges are fictional — net revenue depends entirely on the payer contract and bad debt / charity care write-offs. Always model net patient revenue, never gross.
Gross Revenue = Discharges × CMI × Gross Charge/CMI-adj case
Net Patient Revenue = Gross × (1 − Contractual Adj %) × (1 − Bad Debt %)
Operating Margin = (NPR + Other Revenue − OpEx) / Total Revenue
Days Cash on Hand = Cash / (Operating Expenses / 365)

Dog #2 says: "Regulated utilities are bond-like — predictable, boring, capex-heavy. The model is: rate base × allowed ROE = net income. Simple once you accept the regulator is your silent partner."
Utility models split between regulated (rate-of-return) and merchant (market-price). Regulated utilities earn a set return on their capital base — model capital spending and rate cases. Merchant generation models commodity prices, spark spreads, and capacity market revenues. They look like completely different businesses because they are.
Rate Base = Net Utility Plant + Working Capital + Other Allowed Assets
Allowed Revenue = Rate Base × (Equity% × ROE + Debt% × Rate) + O&M recovery
Merchant Revenue = MWh Generated × Power Price − (Heat Rate × Gas Price)
Spark Spread = Power Price − (Heat Rate × Gas Price)
FFO/Debt = (Net Income + D&A + Deferred Tax) / Total Debt

Dog #3 says: "Pharma models are probability-weighted NPV models. Your pipeline is worth the sum of (peak sales × probability of approval × NPV factor) for each drug. The rest is details."
Pharma models combine two very different businesses: the cash-cow marketed portfolio and the binary-outcome R&D pipeline. Modelers must probability-weight pipeline assets and sensitize against patent cliffs and generic entry timing. Gross-to-net adjustments (rebates, chargebacks) can reduce sticker price by 30–50%.
Product Revenue = Patients × Treatment Rate × Price × Gross-to-Net Adjustment
Pipeline NPV = Σ [Peak Sales × PoS × Patent Life Adjusted NPV]
R&D Spend = % of Revenue or budget-driven
EPS = (Revenue − COGS − SG&A − R&D ± Other) × (1 − Tax Rate) / Shares

Dog #4 says: "Telecom models are subscriber cohort models with big capex hangovers. The question is always: is ARPU growing faster than churn? If yes, build the towers. If no, you're just a declining annuity."
Telecom models track subscriber counts × ARPU minus churn-driven losses. The capital intensity of network buildout (spectrum, towers, fiber) makes FCF timing critical — EBITDA looks great, but capex devours it for years before the network fully monetizes.
Revenue = Subscribers × ARPU
Service Revenue = Post-paid + Pre-paid + Enterprise + Wholesale
EBITDA = Revenue − Network Costs − SG&A (excl. D&A)
FCF proxy = EBITDA − CapEx
Churn Rate = Churned Subs / Opening Subs

Dog #5 says: "Marketplace models are GMV × take rate. The hard part is that your take rate compresses as you scale — buyers and sellers get leverage. Model the take rate as a declining function of GMV."
Marketplace models track gross merchandise value (GMV) — the total value of transactions — then apply the platform's take rate to get revenue. The classic tension is between growing GMV (requires low prices / subsidies) and improving take rate (requires more value-add services).
GMV = Active Buyers × Orders/Buyer × AOV
Revenue = GMV × Take Rate
Contribution Margin = Revenue − Variable COGS − S&M − Incentives
Liquidity = Supply × Demand Conversion Rate

Dog #6 says: "Insurance is a float business. You collect premiums today, pay claims later. The underwriting result tells you if you're profitable on the insurance side. The investment income tells you if you're profitable on the float."
Insurance models separate underwriting (premiums vs. claims + expenses) from investment income (float). Combined ratio is the core metric — above 100% means you're losing money on underwriting and need investment income to compensate. Below 100% means you get paid to hold other people's money.
Net Premiums Written (NPW) = Gross − Ceded (to reinsurers)
Combined Ratio = (Losses + LAE + Underwriting Expenses) / Earned Premiums
Net Income = Underwriting Income + Net Investment Income + Realized Gains − Tax
Investment Income = Float × Investment Yield

Dog #1 says: "Media models are audience × monetization rate. Whether it's CPM, CPC, or subscription, you need to model the audience first — and audiences are the hardest thing to forecast."
Media models bifurcate into advertising revenue (impressions × CPM or clicks × CPC) and subscription / licensing. The secular shift from ad-based to subscription revenue is the dominant trend — model both tracks and the mix shift over time. Content cost is the swing variable that can destroy an otherwise-healthy margin profile.
Ad Revenue = Impressions (000s) × CPM / 1000
Digital Ad Revenue = Sessions × Pages/Session × Fill Rate × CPM
Sub Revenue = Subscribers × ARPU
Licensing = Content Hours × License Rate per Hour

Dog #2 says: "Professional services is a people model. Headcount × bill rate × utilization = revenue. If utilization drops below 70%, you're burning cash. If it's above 85%, your people are burning out."
Services firms model billable headcount × utilization rate × average bill rate. The pyramid structure (partners leverage juniors) determines margin — model partner-to-staff ratios and their respective comp as the key COGS driver. Attrition is an operating risk, not just an HR metric.
Revenue = Billable Headcount × Avg Bill Rate × Utilization Rate × Working Days
Utilization Rate = Billable Hours / Total Available Hours
Gross Margin = Revenue − Direct Staff Cost (incl. benefits)
EBITDA = Gross Margin − Overhead (facilities, G&A, BD)

Dog #3 says: "EdTech models look like SaaS but aren't. Content has high upfront cost and low marginal cost. CAC is high (education is a grudge purchase). Completion rates tell you if you'll get word-of-mouth."
EdTech models blend subscription, course-by-course, and B2B enterprise sales. Content is a depreciating asset — a course launched in 2020 needs refresh spend by 2025. Model content library value alongside subscriber growth and treat content amortization as a real cost, not a non-cash afterthought.
Revenue = (B2C Subs × ARPU) + (Enterprise Seats × Seat License Fee) + Course Sales
Content COGS = Instructor Rev Share + Content Amortization
CAC = Marketing Spend / New Enrollments (or Subs)
LTV = ARPU × Avg Subscription Duration × Gross Margin %

Dog #4 says: "Gaming models are live-service economics: you launch a game and it's a platform. DAU × ARPDAU is the engine. The question is how many of your DAUs are paying players — and how much."
Mobile gaming models use ARPDAU × DAU for live-service titles. The economics pivot on conversion from free to paying — top spenders ("whales") generate the majority of IAP revenue, so whale retention is existential. D1 / D7 / D30 retention curves compound fast: a 1% improvement in D30 retention can double LTV.
Mobile Revenue = DAU × ARPDAU
ARPDAU = Paying User % × ARPPU (avg revenue per paying user)
Premium Revenue = Units Sold × ASP
LTV = D1 Retention × D30 Retention cohort model × ARPDAU
Payback = CPI / D30 LTV

Dog #5 says: "Real estate is a cap rate model. NOI / Cap Rate = Value. If cap rates expand by 50bps and your NOI doesn't grow, you just lost 5–8% of asset value. That's the rate risk nobody talks about at the pitch."
Real estate models layer three analyses: the property-level NOI model, the project-level development return, and the portfolio / REIT model. The discount rate and cap rate assumptions drive valuation far more than operating assumptions — sensitivity tables on cap rates are mandatory, not optional.
NOI = Gross Potential Rent − Vacancy & Credit Loss − Operating Expenses
Cap Rate = NOI / Property Value → Value = NOI / Cap Rate
Cash-on-Cash Return = Annual Pre-Tax Cash Flow / Total Cash Invested
IRR = Discount rate that sets NPV = 0 across holding period
Equity Multiple = Total Distributions / Total Equity Invested

Dog #6 says: "A startup model has one job: show how long until you die, and what it takes to not die. Runway × burn rate × milestones. Everything else is fiction dressed up as planning."
Startup models are burn-rate models with aspirational upside. Build the bottoms-up cost structure honestly — headcount drives 60–80% of costs. Then layer in revenue scenarios. The key deliverable is a runway analysis showing how different revenue outcomes change your cash-out date and next fundraise timing.
Monthly Burn = Operating Expenses − Revenue
Runway = Cash Balance / Monthly Burn
Gross Burn = Total Operating Costs
Net Burn = Gross Burn − Revenue
LTV = (ARPU × Gross Margin %) / Monthly Churn Rate
CAC Payback = CAC / (ARPU × Gross Margin %)
golden rules of financial modeling