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I've been learning HTML5 and responsive web design lately and one of the things I decided to build was a mortgage payment calculator. It's nothing too fancy or complex from a design and coding perspective, but it does the job. The general idea is that a user inputs their property purchase price, down payment, interest rate and amortization period and the calculator spits out the monthly mortgage payment as well as some other calculations that may be useful.

I am looking for people to test it out and provide feedback. I've checked a few calculations in Excel using the PMT function and the calculator duplicates the same numbers so I believe it works. The design of the calculator is suppose to work on all devices and screen sizes, so if you don't mind, please test it on your smartphone, tablet, laptop, desktop etc. and let me know if it displays properly and is usable. Any and all feedback is appreciated :).

Link:
Mortgage Payment Calculator

Text Line Font Screenshot Parallel


Cheers
 

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Andrew I tested this out and my only feedback would be to add more options under Amortization Schedule and also a bi-weekly and weekly Payment Frequency,If it had these two I would bookmark it and use it myself:)

Marina
 

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Works well in chrome on my ubuntu laptop and android smartphone.

The calculator seems to give slightly different results than those used in other online mortgages calculators. I think you're compounding the interest rates monthly whereas Canadian mortgages compound semi-annually.

Line 66 would need to be changed to

var monthly_interest_rate = (Math.pow(Math.pow((1 + interest_rate / 100 / 2),2),(1/12)) - 1);
 

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Discussion Starter · #5 ·
Andrew I tested this out and my only feedback would be to add more options under Amortization Schedule and also a bi-weekly and weekly Payment Frequency,If it had these two I would bookmark it and use it myself:)
Thanks Marina. Good news, I was planning to add weekly and bi-weekly payment frequency to the calculator already :).
 

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Discussion Starter · #6 ·
Maybe also have an extra payments section for options to pay a lump sum to the principal every year, every month, every payment, etc.
Interesting. I know extra principal prepayment is an option with most mortgages that people take advantage of. I suppose if I were to add this feature to the calculator that it might be useful to show how much earlier you are able to pay off the mortgage by making those principal prepayments. Thoughts?
 

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Discussion Starter · #7 ·
Works well in chrome on my ubuntu laptop and android smartphone.

The calculator seems to give slightly different results than those used in other online mortgages calculators. I think you're compounding the interest rates monthly whereas Canadian mortgages compound semi-annually.

Line 66 would need to be changed to

var monthly_interest_rate = (Math.pow(Math.pow((1 + interest_rate / 100 / 2),2),(1/12)) - 1);
Thanks for checking on all those devices Woz. Good point on compounding the interest rate semi-annually vs. monthly. I didn't realize that was a Canadian convention. I'll make the adjustment :)
 

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One thing I would like to see is payment date versus salary date.

Many people think that bi-weekly - accelerated bi-weekly is better than monthly, which may be true but it's really dependent upon you salary frequency - and the time between them simply needs to be minimized..
 

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One thing I would like to see is payment date versus salary date.

Many people think that bi-weekly - accelerated bi-weekly is better than monthly, which may be true but it's really dependent upon you salary frequency - and the time between them simply needs to be minimized..
Matching payment frequency with salary dates is a practical way to ensure that money is in the account when payments are due, and it makes it easier for some people to budget, but there is no inherent benefit to this matching, and there is no magic behind 'accelerated' payments paying off your mortgage more quickly vs. monthly payments, contrary to popular belief.

"Accelerated" payment = increased payment. That's it.

The sum of your annual payments is roughly equal, given the same amortization period, loan amount, and rate. How you choose to pay has a negligible impact in the end, as the interest is compounded semi-annually anyway.

Bi-weekly = 26 payments
Semi-monthly = 24 payments (and is therefore a slightly higher payment than bi-weekly)

Accelerated bi-weekly = taking the higher semi-monthly payment figure and paying it on a bi-weekly basis.

Naturally, a higher payment with everything else being equal results in a lower amortization period; however, the same overall payment increase can be applied to a monthly payment schedule, yielding a near-identical benefit.

Given that lenders have long permitted borrowers to increase their mortgage payment (and make lump-sum payments), "acceleration" is actually an antiquated feature that has for some reason endured over the years.

i.e. pick the payment frequency that is most convenient for you, because you can set your payment to pay off your mortgage in whatever amount of time suits you.
 

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Interesting. I know extra principal prepayment is an option with most mortgages that people take advantage of. I suppose if I were to add this feature to the calculator that it might be useful to show how much earlier you are able to pay off the mortgage by making those principal prepayments. Thoughts?
Andrew,

First off, I like the clean layout of your calculator, and well done! Secondly, the extra principal payment option is exactly what I am looking for in a calculator. There are a hundred simple calculators out there, but very few show how many month and/or years you can trim off when you double down your payments. I am interested in doubling down payments, and annual lump sums (10% in my case) direct to principal. How many years am I saving?

I should also add that I pay weekly, and your only option is monthly. I chose weekly to make it easier to double down and have money go direct to principal -- I would love to see more payment options and the double down option!

Keep up the good work!
 

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Matching payment frequency with salary dates is a practical way to ensure that money is in the account when payments are due, and it makes it easier for some people to budget, but there is no inherent benefit to this matching, and there is no magic behind 'accelerated' payments paying off your mortgage more quickly vs. monthly payments, contrary to popular belief.

"Accelerated" payment = increased payment. That's it.

The sum of your annual payments is roughly equal, given the same amortization period, loan amount, and rate. How you choose to pay has a negligible impact in the end, as the interest is compounded semi-annually anyway.

Bi-weekly = 26 payments
Semi-monthly = 24 payments (and is therefore a slightly higher payment than bi-weekly)

Accelerated bi-weekly = taking the higher semi-monthly payment figure and paying it on a bi-weekly basis.

Naturally, a higher payment with everything else being equal results in a lower amortization period; however, the same overall payment increase can be applied to a monthly payment schedule, yielding a near-identical benefit.

Given that lenders have long permitted borrowers to increase their mortgage payment (and make lump-sum payments), "acceleration" is actually an antiquated feature that has for some reason endured over the years.

i.e. pick the payment frequency that is most convenient for you, because you can set your payment to pay off your mortgage in whatever amount of time suits you.
That was exactly my point. The 'best' choice to minimize the amount of interest you pay on your mortgage as it pertains to payment frequency is to minimize the time your cash is sitting in a 0.1% savings account. To do this you need to synchronize your salary and how your mortgage payment frequency. Get paid monthly - the best payment frequency in monthly; no bi-weely or accelerated bi-weekly or other such nonsense. I've tried to convince Garth Turner of this but I still have not succeeded.
 

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Get paid monthly - the best payment frequency in monthly; no bi-weely or accelerated bi-weekly or other such nonsense.
Maybe I'm misunderstanding you, but how many people have the option of getting paid monthly? And given the choice, would you want your employer keeping your wage for a whole month before you get it?

Most people get paid every two-weeks, which is why a bi-weekly mortgage makes sense - minimizing the time their "cash sits in a 0.1% savings account"...
 

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That's besides the point - the point is if you get paid twice a month, you pay your mortgage twice a month; every two weeks? pay off every two weeks; monthly? then monthly and so on.

People who get paid twice a month are frequently confused into paying every two weeks which is they think will help them pay off their mortgage faster because they are putting in 26 payments rather than 24. That is not how it works.
 

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Very clean calculator. I would definitely add the extra lump-sum options. Perhaps even have a comparison table of 2 calculations below for normal payments and other with lump sum then click on reset to clear the calculation.
 

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That's besides the point - the point is if you get paid twice a month, you pay your mortgage twice a month; every two weeks? pay off every two weeks; monthly? then monthly and so on.

People who get paid twice a month are frequently confused into paying every two weeks which is they think will help them pay off their mortgage faster because they are putting in 26 payments rather than 24. That is not how it works.

You got me confused.

Paying 26 payments per year vs twice a month (24 payments per year) certainly pays off a mortgage sooner. As long as the payment amount is equal.

Show me the math why that is not true.
 

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Of course it does but why would someone do that?

If you have x amount of money to put towards a mortgage you put it on your mortgage - the 24 payments per year would be higher than those 26.

That's why if you are paid twice a month with your mortgage being paid the day after you get paid there is mathematically no possible way to do better than that regardless of payment frequency.
 

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Of course it does but why would someone do that?

If you have x amount of money to put towards a mortgage you put it on your mortgage - the 24 payments per year would be higher than those 26.

That's why if you are paid twice a month with your mortgage being paid the day after you get paid there is mathematically no possible way to do better than that regardless of payment frequency.
I am still confused.
How about giving some numbers and equations?
 

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I am still confused.
How about giving some numbers and equations?
The confusion lies in assuming the bi-weekly and semi-monthly payments are the same, but they are not (to begin with).

e.g. imagine you have 12,000 loan, interest-free, being paid off over one year (to keep the math simple). The natural payments would be:

Monthly payment = 12,000/12 = $1,000.00
Semi-monthly = 12,000/24 = $500.00
Bi-weekly = 12,000/26 = $461.54 (rounded up to the nearest cent).

When you 'accelerate' your bi-weekly payment, you are equalizing it with the semi-monthly payment amount of $500.00, but continuing to make 26 payments per year...that is why the mortgage is paid off sooner.

This isn't special though, because you can also increase your semi-monthly or monthly payment to pay off the loan just as quickly.

Acceleration is an antiquated 'feature', because almost all lenders permit you to increase your regular payment (and make lump sum payments) anyway.

Thus, people ought to just select whatever payment frequency is most convenient for them and increase their payment if they want to pay off the loan sooner.
 
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