Periodic cash flows
For cash flows −1000, 400, 400 and 400 and a 10% period rate, the site’s explicit t=0 model is -1000 + 400/(1+10%) + 400/(1+10%)^2 + 400/(1+10%)^3. In Excel, the corresponding structure is commonly =-1000 + NPV(10%,400,400,400) because Microsoft documents NPV values as end-of-period cash flows.
For a periodic return root, use =IRR({-1000,400,400,400}) and confirm that the resulting rate makes the explicit NPV close to zero. An IRR result is not sufficient when cash-flow signs change more than once.
Dated cash flows
Use XNPV or XIRR when actual dates matter. Match every value with a date, retain the initial date and do not sort values separately from dates. Microsoft XNPV documentation and Microsoft XIRR documentation are the responsible function references used by this model family.
| Site model | Excel-style equivalent | Parity check |
|---|---|---|
| Periodic NPV with t=0 | =initial + NPV(rate, later_flows) | Same period rate and equal intervals |
| Periodic IRR | =IRR(all_flows) | Result drives explicit NPV to zero; diagnose multiple roots |
| Dated XNPV | =XNPV(rate, values, dates) | Same dates and day-count convention |
| Dated XIRR | =XIRR(values, dates) | Result drives XNPV to zero; do not hide convergence failure |
| MIRR | =MIRR(values, finance_rate, reinvest_rate) | Both rates are explicit and independently justified |