smartmoney77-calculators

15+ financial calculator functions for Node.js and the browser. Zero dependencies, fully typed.

Used by SmartMoney77.com — free financial calculators in 6 languages.

Install

npm install smartmoney77-calculators

Functions

| Function | Description | |---|---| | compound() | Compound interest with monthly contributions | | fire() | FIRE (Financial Independence) target calculator | | fireYears() | Years to reach a savings target | | monthlyToTarget() | Monthly savings needed for a goal | | costOfWaiting() | Cost of delaying investments | | latteFactor() | Small daily expenses compounded over time | | workHours() | How many work hours a purchase costs | | feeImpact() | Long-term impact of investment fees | | inflation() | Purchasing power erosion over time | | creditPayoff() | Credit card payoff timeline | | creditInterest() | Total interest on credit card balance | | emergencyFund() | Emergency fund target and gap analysis | | emergencyGap() | Emergency fund gap amount | | educationRoi() | Return on investment of education | | zakat() | Islamic Zakat obligation calculator |

Quick Start

import { compound, fire, latteFactor } from 'smartmoney77-calculators';

// Compound interest: $10k initial + $500/mo at 7% for 20 years
const result = compound(10000, 500, 7, 20);
console.log(result.futureValue);    // ~268,549
console.log(result.totalInterest);  // ~138,549

// FIRE calculator: $40k/yr expenses, $100k saved, $2k/mo, 7% return
const fireResult = fire(40000, 100000, 2000, 7);
console.log(fireResult.targetAmount);  // 1,000,000
console.log(fireResult.yearsToFire);   // ~15.8

// Latte Factor: $5/day coffee invested at 7% for 30 years
const latte = latteFactor(5, 7, 30);
console.log(latte.investedValue);  // ~182,000+

API

Every function accepts plain numbers and returns a typed result object. All monetary values are rounded to 2 decimal places.

Rates are always expressed as percentages (e.g., 7 for 7%, not 0.07).

compound(principal, monthlyContribution, annualRate, years)

Returns { futureValue, totalContributions, totalInterest }

fire(annualExpenses, currentSavings, monthlyContribution, annualReturn)

Returns { targetAmount, yearsToFire, monthlyRequired }

fireYears(currentSavings, monthlyContribution, annualReturn, target)

Returns number (years as decimal)

monthlyToTarget(currentSavings, annualReturn, years, target)

Returns number (required monthly contribution)

costOfWaiting(monthlyContribution, annualReturn, years, delayYears)

Returns { ifStartNow, ifWait, costOfWaiting }

latteFactor(dailyAmount, annualReturn, years)

Returns { dailyCost, monthlyCost, yearlyCost, investedValue }

workHours(annualSalary, hoursPerWeek, itemCost, taxRate?)

Returns { hoursPerItem, itemsPerHour, effectiveHourlyRate }

feeImpact(principal, monthlyContribution, annualReturn, annualFee, years)

Returns { withoutFees, withFees, feeCost, feePercentageOfGains }

inflation(currentAmount, inflationRate, years)

Returns { futureNominalValue, futurePurchasingPower, purchasingPowerLoss }

creditPayoff(balance, annualRate, monthlyPayment)

Returns { monthsToPayoff, totalPaid, totalInterest }

creditInterest(balance, annualRate, months)

Returns number (total interest)

emergencyFund(monthlyExpenses, targetMonths?, currentSavings?, monthlySavings?)

Returns { targetAmount, currentAmount, gap, monthsToFill }

emergencyGap(monthlyExpenses, targetMonths, currentSavings)

Returns number (gap amount)

educationRoi(tuitionCost, yearsOfStudy, currentSalary, expectedSalary, opportunityCost?)

Returns { totalCost, salaryIncrease, paybackYears, tenYearRoi, roiPercentage }

zakat(cashAndBank, goldValue?, silverValue?, investments?, otherAssets?, liabilities?, goldPricePerGram?)

Returns { totalWealth, nisabThreshold, isZakatDue, zakatAmount }

License

MIT — SmartMoney77.com