PHP installment calculator with interest rate

v1.0.0 2020-12-24 15:44 UTC

This package is auto-updated.

Last update: 2022-11-23 00:38:13 UTC


This class can calculate the amount of installments on loans.

It can take as parameters the loan amount, the interest rate and the identification of the method to use to calculate the installments.

The class can returns the values related with installment payments like the total amount or the interest amount to be returned after a given number of months.

Latest Stable Version tests Build Status PHPStan StyleCI Total Downloads License


  • PHP 7.3+


To get the latest stable version of this component use:

"require": {
    "springy-framework/installment-calc": "*"

in your composer.json file.


I suppose that the following example is all you need:


require 'vendor/autoload.php'; // If you're using Composer (recommended)

// Creates the object. Only the principal value is requered in constructor.
$installment = new Springy\InstallmentCalc(

    Interst formula constants explained

    Springy\InstallmentCalc::FORMULA_SIMPLE - Simple interest
    Springy\InstallmentCalc::FORMULA_COMPOUND - Compound interest
    Springy\InstallmentCalc::FORMULA_BCB - Brazilian Central Bank interset formula

// Gets future amount for 12 months
echo $installment->getFutureAmount(12);

// Gets total interest for 12 months
echo $installment->getInterest(12);

// Gets monthly installment for 12 months
echo $installment->getMonthlyInstallment(12);

// Gets current principal amount
echo $installment->getPrincipalAmount();

// Gets current interest formula method
echo $installment->getFormulaMethod();

// Gets current interes rate
echo $installment->getInterestRate();

// Changes the principal amount value

// Changes the interest formula value

// Changes the interest rate value


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This project is licensed under The MIT License (MIT).