The StrawStickStone Mortgage Scenario Analysis Calculator

This is my new favorite entry EVER.

Let's Play!

I've spent the past week explaining why it's so important to do serious comparison shopping and saving up before you apply for a loan. On Monday we investigated how you could save up to 35% over the life of your loan by working with discount points and down payments. On Wednesday I used a salad dressing analogy to explain APR and how it affects your bottom line. For today I've gone back to my nerdy coding roots and have made a pretty hefty calculator so you can play with the numbers yourself.

The calculator below asks for only two simple figures - the price of a property you want to buy (or perhaps one you already own) and how many years you plan to stay there. It takes that info, combines it with the current Illinois mortgage rates and spits out the results based on five different scenarios. The scenarios were chosen to best exemplify some typical home buyer situations.

  • Scenario 1 - Goody two-shoes. This buyer has a good job & good credit, has done some aggressive research, and has concentrated on saving up a chunky down payment.
  • Scenario 2 - Old-school traditional. (Added by reader request!) This is the traditional, expected American home loan. You save up a good down payment but with a family on the way you want to keep your monthly payments low. You do as much research as you can but you're a busy person. This is the "standard" 20% down, 30 year fixed rate loan.
  • Scenario 3 - New to town. You haven't had much time to save up cash, either because you just moved to Chicago or you had to sell your last home for less than expected. Still, you've done the best you can. You moved here with a good job so you can afford slightly higher monthly payments and you've diligently comparison-shopped your loan.
  • Scenario 4 - Middle of the road. This is the typical first-time buyer. You heard something about needing good credit to get a mortgage, so you've been scrubbing your credit score at the expense of your savings. You shop your loan around a little because your Realtor says you need a pre-approval before you go looking at houses. You've got a decent job, but it's definitely entry-level.
  • Scenario 5 - Thank goodness you're here! You need help. You've got a low paying job, low savings, and your credit is damaged. You have no idea where to start, and you're going to have to take a subprime interest rate to get a loan at all.

Once you've figured out which scenario suits you best, plug in some numbers and have at it.

A Few Rules

This only works for loans below the current conforming maximum of $417,000. (That means a purchase price of $438,948.) If you try and insert a price point that will lead to the loan tipping over into the "jumbo" category, the calculator will block you.

Rates are updated once a day.

As this is a Chicago Real Estate blog, I'm using Illinois rates.

This is NOT a mortgage quote, it isn't a binding estimate, it isn't a contract, it doesn't imply any sort of obligation between StrawStickStone and you to lend you money at these rates, nor does it guarantee that you will even be able to get these rates if you go mortgage shopping. It is merely meant as a teaching tool to help mortgage newcomers to understand how large of an effect all the little variables can have on your bottom line.

This assumes that you will at least break even on the value of the property when you sell it. This is not always a given, but for the sake of focusing on the mortgage variables I had to ignore the ones from the sales market.

This does not include property taxes. This is just focusing on mortgage principal, interest and PMI.

I coded this from scratch. If you see a bug or if you want a calculator like this for your site, please don't hesitate to contact me. Please don't nick my code without asking first.

The Calculator

What is the purchase price of the property? $
And how many years do you plan to keep it?


Today's average Illinois Mortgage Rates (via Zillow API): 30 Year fixed: % | 15 Year fixed: %

Results: How much will that mortgage really cost you?

Scenario 1 Scenario 2 Scenario 3 Scenario 4 Scenario 5
20% Down
4 discount points
15 year loan
No finance fees
Prime interest rate.
20% down
2 discount points
30 year loan
$1200 in fees
Prime interest rate..
10% down
2 discount points
15 year loan
No finance fees
Prime interest rate.
5% down
No discount points
30 year loan
$1200 in fees
Prime interest rate.
5% down
No discount points
30 year loan
$2400 in fees
Subprime interest rate.
Cash to close
incl. closing costs
$$$$$
Monthly Payment
incl. PMI if needed
$$$$$
Total Interest Paid
after years
$$$$$
Total Exit Cost
after years
$$$$$

The mortgage scenario analysis calculator is © Cutefuzzy Multimedia & Marketing, Inc., 2012. (That's my web development company!)

Print Friendly

2 Responses so far.

  1. Ryan says:

    Make a 30 year option for 20%………………………..

    • Kay Cleaves Kay Cleaves says:

      Good point, that’s the old school traditional scenario. I can do that. Might be tight to fit it into the current layout but I’ll figure something out.

      EDIT, 90 minutes later: Done! It’s now scenario #2 and everything else has been bumped down. Thanks for the suggestion!

Hi! Please note that I'm no longer a licensed Realtor and I don't check the comments very often anymore. You're welcome to leave questions but be aware that it may be a few months before I see it. For faster response, please use the Contact page to email me your questions.

-Kay C.

Leave a Reply

Your email address will not be published. Required fields are marked *