dork-e.com

This has probably been done before, but this script fixes two problems I’ve noticed with loan calculators:

1. They assume monthly interest compounding (most loans are compounded daily)
2. They don’t allow you to calculate the payments if you’re splitting your payment (eg: paying $200 twice a month instead of $400 once a month)

#/usr/bin/env python
import math

# Remaining amount on the loan
toPayOff = 12345.67
# Interest rate
intRate = 12.34
# Amount of your payment
payAmt = 200
# Making the payment every x days
payEvery = 15
# Maximum amount you're willing to pay extra to just "pay it off"
balloonMax = 200
# Days til the next payment
runUpDays = 15

# Do not edit below this line
days = 0
pmtNum = 0
dailyInt = (intRate / 100) /365
origToPayOff = toPayOff
totalPaid = 0
while (runUpDays > 0):
    toPayOff = (math.ceil((toPayOff * (1 + dailyInt))*100))/100
    runUpDays -= 1
while (toPayOff > 0):
    days += 1
    toPayOff = (math.ceil((toPayOff * (1 + dailyInt))*100))/100
    if (days % payEvery == 0):
        toPayOff = (math.ceil(toPayOff * 100))/100
        if (toPayOff < (payAmt + balloonMax)):
            payAmt = toPayOff
        toPayOff -= payAmt
        pmtNum += 1
        totalPaid += payAmt
        print "Payment #%s\tPayment Amt: $%s\tBalance:%s" % (pmtNum,payAmt,toPayOff)
print "Over %s payments, you will pay a total of $%s ($%s in interest)" % (pmtNum,totalPaid,(totalPaid-origToPayOff))