NPV, IRR & XIRR
IRR by bisection, so a sign-change-heavy series does not converge on a confident wrong answer.
- Runs
- In this tab
- Data sent
- None
- Rounding
- Once, at the end
- Also in
- The Chrome extension
NPV, IRR & XIRR, worked
Showing a worked example — type over it
Result
Where these numbers come from.
Negatives are parenthesised because that is what a statement does. The rest is four promises.
Minor units, never floats
Amounts are integers in the currency's smallest unit, end to end. A float never touches a cent.
Rounded once
Rounded once, at the end — never per operand, which is how a split stops summing to the whole.
Unit tested
The arithmetic lives in one unit-tested module, shared without reimplementation with the extension.
No network
There is no request to make. What you type stays in this tab and is gone when you close it.
More in money maths
- VAT / sales taxGross to net is a division, not a multiplication. The three figures always add back up.
- Margin & markupThey are not the same number, and confusing them is how a price list quietly loses money.
- FX conversion & gain/lossThe rate is the one in your policy, so you type it. No live rate, no network call, no stale surprise.
- Penny-exact allocationSplit 100.00 three ways and get 33.34 / 33.33 / 33.33 — never a cent left in suspense.
- Effective vs nominal rate12% compounded monthly is 12.68%. That difference is the covenant you either pass or fail.
Read it in context
- Founder guide · 4 minWhy startups should close their books every monthA monthly close turns a bank balance into numbers an investor, an auditor or a 409A firm will accept. What it is, and why it gets expensive to skip.
- Founder guide · 3 minBurn rate and runway: how to calculate them correctlyGross burn, net burn and months of runway, done the way an investor checks them: from cash, averaged, and with the hires you’ve already committed to.
- Founder guide · 5 minCash flow statement explained: why profit isn’t cashHow the cash flow statement starts at net income, adds back non-cash costs and working capital, splits three activities and ties to the balance sheet.
The same number, elsewhere.
A calculator answers the question once. These carry the answer into a product, name what it computed, and argue the method.
- ComponentForecastTableProjections dashed and labeled everywhere.
- ComponentMetricDefinitionEvery metric requires one. Formula with values substituted.
- ComponentMoneyChartLine/area with a money axis and negative-aware baseline.
- TermFree cash flowFree cash flow is a cash and runway metric, calculated as Operating cash flow − Capital expenditures.
- TermRunwayRunway is a cash and runway metric, calculated as Cash ÷ net monthly burn.
- DocMetric definitionsEvery metric in this system ships with its formula, its period, its inputs, and its source. A KPI without a definition is a number people argue about in meetings.
- DocCurrency decimal placesHow many decimals each ISO 4217 code is stored at — JPY 0, USD 2, KWD 3.