finance
Money-math capability pack: compound interest, loan amortization + full schedules, mortgage breakdown, time-value-of-money (present/future value, NPV, IRR via Newton's method, PMT), business ratios...
finance (adapter system)
Money-math capability pack — Studio-aligned, monetizable business tools. Pure JS, zero deps. Everything a small-business / CRM surface needs to quote loans, price products, model investments, and format money correctly.
Rates are decimals everywhere (0.06 = 6%), never percents. Money outputs round to 2 decimals (via integer cents to avoid float drift). Amortization/depreciation schedules keep running balances consistent — the final payment is trued-up so the balance lands exactly on 0.
Tools (adapters)
| tool | args | result |
|---|---|---|
compoundInterest | { principal, rate, times=12, years, schedule? } | { futureValue, interestEarned, periods, schedule? } |
loanAmortization | { principal, annualRate, termMonths } | { monthlyPayment, totalInterest, totalPaid, schedule:[{month,payment,principal,interest,balance}] } |
mortgage | { price, downPayment?, annualRate, termYears, taxRate?, insurance? } | { loanAmount, monthly:{principalAndInterest,tax,insurance,total}, totalPaid, totalInterest } |
presentValue | { futureValue, rate, periods } | { presentValue } |
futureValue | { presentValue, rate, periods } | { futureValue } |
npv | { rate, cashflows:[] } | { npv } |
irr | { cashflows:[], guess? } | { irr, iterations, method } (Newton + bisection fallback) |
pmt | { rate, periods, presentValue, futureValue? } | { payment } |
roi | { gain, cost } | { roi, roiPercent, netProfit } |
cagr | { begin, end, years } | { cagr, cagrPercent } |
breakEven | { fixedCosts, pricePerUnit, variableCostPerUnit } | { breakEvenUnits, breakEvenRevenue, contributionMargin } |
depreciation | { cost, salvage?, life, method? } | { method, schedule:[{year,expense,accumulated,bookValue}] } |
currencyFormat | { amount, currency='USD', locale='en-US' } | { formatted, amount, currency, locale } |
tip | { amount, percent, split=1 } | { tip, total, perPersonTip, perPersonTotal } |
depreciation.method accepts 'straight-line' (default) or 'double-declining'. cashflows are ordered [t0, t1, ...]; negatives are outflows. taxRate in mortgage is an annual property-tax rate (decimal) applied to the home price.
Usage
const m = await import('./index.js');
const finance = m.default.adapters;
finance.loanAmortization({ principal: 10000, annualRate: 0.06, termMonths: 12 });
// → { monthlyPayment: 860.66, totalInterest: 327.9, totalPaid: 10327.9, schedule: [...] }
finance.currencyFormat({ amount: 1234.5 }); // → { formatted: '$1,234.50', ... }DRY boundary
The numbers pack owns generic numeric-series analytics (running average, percentile insights, anomaly detection, unit/base conversion). finance owns money math (interest, loans, TVM, depreciation, currency formatting). They do not overlap — keep money math here.