How to Build a Real Estate Pro Forma (Step-by-Step)

Start with the revenue stack: gross potential to effective gross income

Every pro forma begins with revenue, built line by line rather than as a single lump sum. Start with Gross Potential Rent (GPR)—the rent you would collect if every unit or square foot were leased at market rate, 100% of the time. From GPR you subtract loss-to-lease (the gap between in-place and market rent), then vacancy loss, and credit/collection loss (concessions, bad debt). Add back Other Income—parking, laundry, RUBS/utility reimbursements, storage, pet fees, or for commercial assets, CAM reimbursements and percentage rent. The result is Effective Gross Income (EGI), the realistic top line that drives everything below it.

• •Gross Potential Rent (GPR) = market rent × total units/SF × 12 months
• •Less: loss-to-lease, physical vacancy (typically 5–10% for stabilized multifamily), concessions, and bad debt
• •Plus: other income and expense reimbursements (CAM, taxes, insurance for NNN leases)
• •Effective Gross Income (EGI) = GPR − economic vacancy + other income

Project operating expenses honestly—and separate them from capital

Operating expenses (OpEx) are the recurring costs to run the property: property taxes, insurance, utilities, repairs and maintenance, payroll, management fee (usually 3–5% of EGI), marketing, and general/administrative. Model each as its own line, grown by an inflation assumption (often 2–3% annually), because lumping them into a single percentage hides the biggest risk in most deals—property tax reassessment on sale. The single most important discipline here is keeping capital expenditures OUT of OpEx: replacement reserves, tenant improvements (TIs), leasing commissions (LCs), and renovation capital sit below NOI, because NOI must reflect the property's stabilized operating performance independent of financing and one-time capital events.

Calculate NOI—the number the whole deal turns on

Net Operating Income is Effective Gross Income minus operating expenses, and it is the pivot point of the entire pro forma. NOI = EGI − OpEx. It excludes debt service, capital expenditures, depreciation, and income taxes by definition, which is precisely what makes it comparable across deals and financeable by lenders. NOI drives your valuation (Value = NOI ÷ cap rate), your exit price (exit-year NOI ÷ exit cap rate), and your primary lender coverage tests. A pro forma that gets NOI wrong—by burying capital in OpEx, using aggressive market rents, or under-reserving—produces a confidently precise but useless answer. Every NOI line should trace back to a source: a signed lease, a T-12, a real tax bill, or an explicit, defensible assumption.

Layer in debt: sizing the loan and computing debt service

Financing turns unlevered property cash flow into levered investor returns. Size the loan against three constraints and take the most restrictive: loan-to-value (LTV, e.g. 65–75% of purchase price), loan-to-cost (LTC, for value-add or development), and a debt-service coverage ratio (DSCR) or debt-yield minimum. Annual debt service = loan amount amortized at the note rate over the amortization period (interest-only during the hold shifts cash flow earlier). Then verify coverage: DSCR = NOI ÷ annual debt service (lenders typically require 1.20–1.35x), and debt yield = NOI ÷ loan amount (often an 8–10% floor). Cash flow after debt service—NOI minus debt service minus capital reserves and TI/LC—is what actually flows to the equity.

• •Loan amount = MIN(LTV × value, LTC × total cost, NOI ÷ min debt yield, sized to min DSCR)
• •DSCR = NOI ÷ annual debt service (must clear the lender's floor every year)
• •Debt yield = NOI ÷ loan amount (a leverage-neutral risk check)
• •Levered cash flow = NOI − debt service − capital reserves − TI/LC

Model the exit and solve for returns

A pro forma is only complete once you model the sale. Estimate exit-year NOI (typically the year after your hold, e.g. Year 6 NOI for a 5-year hold), divide by an exit cap rate—held flat or expanded conservatively versus your entry cap—to get gross sale price, then subtract selling costs (2–3%) and the outstanding loan balance to get net sale proceeds to equity. With the full cash flow stream assembled—negative equity outlay at close, annual levered cash flows, and the lump-sum reversion at sale—you can compute the return metrics that decide the deal: IRR (the annualized discount rate that sets the net present value of the cash flow stream to zero), equity multiple (total distributions ÷ total invested), cash-on-cash return (annual cash flow ÷ equity invested), and average annual return. These are what land in the investment committee memo.

Stress-test it: scenarios, sensitivities, and the equity waterfall

A single-point pro forma is a starting hypothesis, not an answer. Run scenarios (downside, base, upside) by flexing the assumptions that move returns most, and build a two-variable sensitivity table—almost always exit cap rate against rent growth or purchase price—to see how IRR degrades at the edges. If cap rates expand 50–75 bps, does the deal still clear your hurdle? Finally, if you are raising outside capital, the property-level cash flows must pass through a GP/LP equity waterfall: a preferred return to LPs, a GP catch-up, and promote splits above hurdles, with clawback protection. LP returns and sponsor economics can differ sharply from the deal-level IRR, and that distinction is exactly what your investors will scrutinize. This is where a purpose-built engine earns its keep. Origentic runs revenue, OpEx, NOI, debt sizing, sensitivity tables, and full GP/LP waterfalls on one deterministic calc engine—math verified in code against a frozen test-vector suite, so every number traces to a source rather than a spreadsheet cell someone forgot to update.