@u-dev/unison-calculators

unison-calculators

Scenario Calculator

HomeBuyerScenarioCalculator

The HomeBuyer scenario calculator can be used to calculate the outcome of a homebuyer deal.

To get started initialize a HomeBuyerCalculator instance and run the #calculate function.

For instance, I could run:

let calculator = new HomeBuyerScenarioCalculator()
calculator.calculate(500000,50000,100000,{
  isNewConstruction: false
})

And expect

{
  finalPriceChange: 100000,
  initialHomeValue: 500000,
  unisonInvestment: 50000,
  unisonLeverage: 4,
  unisonSharingPercentage: 0.4,
  unisonInvestmentPercentage: 0.1,
  futureSalePrice: 600000,
  unisonPayment: 90000,
  unisonShareInChange: 40000
}

API documentation:

// .initialize
new HomeBuyerScenarioCalculator()

// #calculate()
// @param {number} initialHomeValue - The initial home value
// @param {number} unisonInvestment - The amount unison has invested
// @param {number} finalPriceChange - The change in value you want to calculate for
// @param {object} [options={}] - optional modifiers for calculations
// @param {boolean} [options.isNewConstruction=false] - toggles pricing (non-new construction homes have better pricing)
calculator.calculate(500000, 50000, 100000, {
  isNewConstruction: false
})

HomeOwnerScenarioCalculator

The HomeOwner scenario calculator can be used to calculate the outcome of a homebuyer deal.

To get started initialize a HomeBuyerCalculator instance and run the #calculate function.

For instance, I could run:

let calculator = new HomeOwnerScenarioCalculator()
calculator.calculate(500000, 50000, 100000, {
  qualifiesForNewPricing: false
})

And expect

{
  finalPriceChange: 100000,
  initialHomeValue: 500000,
  unisonInvestment: 50000,
  unisonLeverage: 4,
  unisonSharingPercentage: 0.4,
  unisonInvestmentPercentage: 0.1,
  futureSalePrice: 600000,
  unisonPayment: 90000,
  unisonShareInChange: 40000
}

API documentation:

// .initialize
new HomeOwnerScenarioCalculator()

// #calculate()
// @param {number} initialHomeValue - The initial home value
// @param {number} unisonInvestment - The amount unison has invested
// @param {number} finalPriceChange - The change in value you want to calculate for
// @param {object} [options={}] - optional modifiers for calculations
// @param {boolean} [options.qualifiesForNewPricing=false] - toggles pricing (this is new pricing A.K.A. purchased in last year, which has better pricing)
calculator.calculate(500000, 50000, 100000, {
  qualifiesForNewPricing: false
})

Mortgage Calculators

HomeBuyerMortgageCalculator

The homebuyer mortgage calculator can be used to calculate mortgage payments with and without Unison.

To get started, initialize a new calculator with (optionally) an object containing any assumptions you want to overwrite.

You can then use the #calculate function to see payment outcomes for various combinations.

For instance, I could run:

var calculator = new HomeBuyerMortgageCalculator({assumptions: {mortgageYears: 30}})
calculator.calculate(500000,.1,.1)

And expect:

{
  assumptions: {
    mortgageYears: 30,
    annualMortgageInsurancePremium: 0.0074,
    annualMortgageInterestRate: 0.04,
    annualPropertyInsuranceRate: 0.003,
    annualPropertyTaxRate: 0.0125,
  },
  monthlyMortgagePayment: -1910,
  monthlyPMIPayment: 0,
  monthlyPropertyTaxPayment: -521,
  monthlyPropertyInsurancePayment: -125,
  totalMonthlyPayments: -2556,
  clientDownPaymentAmount: 50000,
  unisonDownPaymentAmount: 50000,
  downPaymentAmount: 100000,
  hasPMI: false,
}

Here are the default assumptions for any new calculator:

const DEFAULT_ASSUMPTIONS = {
  mortgageYears: 30,
  annualMortgageInterestRate: .04,
  annualPropertyTaxRate: .0125,
  annualPropertyInsuranceRate: .003,
  annualMortgageInsurancePremium: .0074,
}

API documentation:

// @param {object} [options={assumptions={}}] - The default set of options
// @param {number} [options.assumptions.mortgageYears] - Length of mortgage in years
// @param {number} [options.assumptions.annualMortgageInterestRate] - Annual loan interest rate
// @param {number} [options.assumptions.annualPropertyTaxRate] - Annual property tax rate
// @param {number} [options.assumptions.annualPropertyInsuranceRate] - Annual property insurance rate
// @param {number} [options.assumptions.annualMortgageInsurancePremium] - PMI rate
new HomeBuyerMortgageCalculator(options)

// @param {number} homePrice - The initial home value
// @param {number} clientDownPaymentPercentage - The percent of the loan, expressed as a decimal, that the client paid down
// @param {number} unisonDownPaymentPercentage - The percent of the loan, expressed as a decimal, that unison paid down
calculator.calculate(500000,.1,.1)