Build a Feasibility Study in Excel: NPV, IRR & Payback
A feasibility study answers one question: is this project worth the investment? Done in Excel, it turns your assumptions about costs, revenue, and financing into hard numbers — net present value, internal rate of return, payback period, and return on investment. This guide walks through building each piece, formula by formula.
What a feasibility study answers
A feasibility model compares the money you put in against the money the project returns over its life, adjusted for the time value of money. It produces a handful of decision metrics — NPV, IRR, payback, ROI — that let you compare very different projects on the same footing, and see how sensitive the outcome is to your assumptions.
Setting up your inputs
Start with a dedicated Inputs sheet: initial investment (CAPEX), project lifetime in years, annual revenue and its growth rate, annual operating expenses (OPEX) and their growth, the discount rate, and the tax rate. Put each in its own labeled cell and reference those cells everywhere — so one change re-runs the whole model, which is the point of doing it in Excel rather than on paper.
Building the cash flow
Build a table with one column per year, from year 0 (the initial investment, a negative number) through the final year. Each year's net cash flow is revenue minus operating expenses minus tax (and minus any loan payments). Grow revenue and OPEX by their rates each year. This row of yearly net cash flows is the input to every metric that follows.
Choosing a discount rate
The discount rate reflects what your money could earn elsewhere and the risk of the project — often the cost of capital or a required rate of return. It matters enormously: a higher discount rate shrinks the value of distant cash flows and can flip a project from attractive to unattractive. Keep it as an input cell so you can test different values.
Net present value with =NPV
NPV discounts every future cash flow back to today and sums them. In Excel: =NPV(rate, year1:yearN) + year0. Note the quirk — Excel's NPV assumes the first value is one period in the future, so you add the year-0 investment separately (it is already 'today'). A positive NPV means the project earns more than your discount rate; negative means it destroys value.
Internal rate of return with =IRR
IRR is the discount rate at which NPV equals zero — effectively the project's own rate of return. In Excel: =IRR(year0:yearN), including the negative year-0 investment in the range. Compare IRR to your required rate: if IRR exceeds it, the project clears the bar. IRR can mislead with unusual cash-flow patterns, so always read it alongside NPV.
Payback, discounted payback and ROI
Payback period is how many years until cumulative cash flow turns positive — a simple risk gauge. Discounted payback does the same on discounted cash flows, so it is more honest. ROI is total net profit divided by the investment. None of these replaces NPV/IRR, but together they describe how fast and how well the money comes back.
Adding loans and depreciation
If the project is financed, add a loan amortization schedule (see our mortgage amortization guide) and subtract the payments in the cash flow. Depreciation does not move cash directly but reduces taxable income, so it lowers the tax line — model it as a straight-line deduction over the asset's life. Both change the after-tax cash flow and therefore every metric.
Common pitfalls
Watch for: the Excel NPV year-0 trap (adding the investment inside the range instead of separately); mixing nominal and real rates; forgetting tax or financing costs; and building a static model with hardcoded numbers you cannot re-run. A good feasibility model is fully formula-driven so you can change one assumption and watch every metric update.
Prefer it done for you?
The Feasibility Excel Builder generates a complete, formula-driven model — cash flow, NPV, IRR, ROI, payback, loan schedules and depreciation — ready to download and adjust.
Build my feasibility Excel — $20Financing part of the project with a loan?
See our mortgage amortization guide to build the loan schedule you'll plug into the cash flow above.
Mortgage amortization guideFrequently asked questions
How do I calculate NPV and IRR in Excel?
Put each period's net cash flow in a row, then use =NPV(rate, range) and add the year-0 outlay separately, and =IRR(range) for the return. If you would rather not wire it up by hand: Try the Feasibility Excel Builder
What's the difference between NPV and IRR, and which should I trust?
NPV is the value added in currency terms at the discount rate you choose; IRR is the rate at which the project breaks even. Prefer NPV for accept/reject decisions — IRR can mislead with unconventional cash flows or when comparing mutually exclusive projects.
What discount rate should I use?
Use your cost of capital or your required rate of return. Because NPV is very sensitive to this input, test a range of rates with a sensitivity table instead of relying on a single number.
Is there a free feasibility study Excel template to download?
You can build one yourself with the steps in this guide, or generate a ready-made model tailored to your own numbers with our builder — with live formulas rather than a static template.
How do I model a real-estate project's cash flow in Excel?
Lay out revenue and costs on the same per-period timeline as any feasibility model, but add the real-estate-specific layers: gross rental income minus vacancy and operating expenses to get NOI, debt service on any acquisition or construction loan, and — critically — a terminal value in the exit year from either a sale price or NOI ÷ exit cap rate. Discount the full stream (annual NOI net of debt service, plus the exit proceeds) at your required return. For a rental or income property this gives you the same NPV, IRR and cash-on-cash metrics as any project, but built around cap rate and NOI instead of just revenue and OPEX.
What is the Excel NPV year-0 trap?
=NPV assumes the first value in the range is one period in the future, so including the initial outlay inside the range discounts it incorrectly. Keep year 0 outside the NPV() range and add it separately.
How accurate is an AI-built feasibility model versus building it manually?
It uses the same standard Excel formulas (NPV, IRR, PMT) linked live to input cells, so nothing is hard-coded. Every cell is auditable and editable — change an input and the whole model recalculates as it would if you had built it yourself.