Fin-Toolkit-Pro

A modular financial library for calculating interest, EMIs, and more.

Installation

npm install fincalc-pro

Usage

const { Interest, Loans } = require('fincalc-pro');

// 1. Calculate Simple Interest
// principal: 1000, rate: 5%, time: 1 year
const simple = Interest.simple(1000, 5, 1);
console.log(simple); // 50

// 2. Calculate Compound Interest
// principal: 1000, rate: 5%, time: 2 years
const compound = Interest.compound(1000, 5, 2);
console.log(compound); // 102.5

// 3. Rule of 72 (Years to double principal)
const years = Interest.yearsToDouble(8);
console.log(years); // 9

// 4. Monthly EMI (Reducing Balance)
// principal: 100000, rate: 10%, months: 12
const emi = Loans.emi(100000, 10, 12);
console.log(emi); // 8791.59

// 5. Total Interest Payable over life of loan
console.log(Loans.totalInterest(10000, 10, 60)); 

// 6. Loan Tenure Calculator
// If I afford $200/mo, how many months to pay off $5k at 12%?
console.log(Loans.calculateTenure(5000, 12, 200));

// 7. Amortization Schedule
const schedule = Loans.amortizationSchedule(10000, 10, 3);
console.table(schedule);

## Formula's Used
Simple Interest: Interest = P * (r / 100) * t
(Where P = Principal, r = Annual Rate, t = Time in Years)

Compound Interest: Amount = P * (1 + (r / 100) / n)^(n * t)
(Where n = Compounding Frequency per year)

Loan EMI (Reducing Balance): EMI = [P * r * (1 + r)^n] / [(1 + r)^n - 1]
(Where r = Monthly Interest Rate, n = Total Months)

Loan Tenure: n = log(E / (E - P * r)) / log(1 + r)
(Where E = Monthly EMI)

Rule of 72 (Doubling Time): Years ≈ 72 / r