In early February Sujit asked a question at Chandoo.org, original post.
I require a formula stating criteria [0%-25% output will be 0, 26%-50% output will be 0.1, 51%-75% output will be 0.2, 76%-100% output will be 0.3 & 100% + output will be 0.4]
Kyle, responded with a neat Sumproduct formula
=SUMPRODUCT((B3>{0.25,0.5,0.75,1})*0.1)
I think it is so neat that it is worthy of sharing and detailing here at Formula Forensics:
So today we will pull Kyle’s answer apart to see what’s inside.
Kyle’s Formula
As usual we will work through this formula using a sample file for you to follow along. Download Here.
Kyle’s formula is a Sumproduct based formula
=SUMPRODUCT((B3>{0.25,0.5,0.75,1})*0.1)
Lets look at cell C3 as our example.
;
In C3 we see the formula: =SUMPRODUCT((B3>{0.25,0.5,0.75,1})*0.1)
Which consists of a Sumproduct function and a formula inside the sumproduct.
We know from Formula Forensics 007 that Sumproduct, Sums the Product of the Arrays, and that when there is only 1 array it simply sums the array elements.
In this case the Sumproduct only has a single array as an element
=SUMPRODUCT((B3>{0.25,0.5,0.75,1})*0.1)
and so the (B3>{0.25,0.5,0.75,1})*0.1 component must return an Array of elements for the Sumproduct to sum.
If we now look at the (B3>{0.25,0.5,0.75,1})*0.1 component.
We can see that it consists of a comparison B3>{0.25,0.5,0.75,1}
The result of the comparison is Multiplied by 0.1.
Sujit’s orginal question asked: 0%-25% output will be 0, 26%-50% output will be 0.1, 51%-75% output will be 0.2, 76%-100% output will be 0.3 & 100% + output will be 0.4
And Kyles formula is using B3>{0.25,0.5,0.75,1} to work out which category the value in B3 belongs to.
We can see this if in a blank cell say C5: we enter the following:
= B3>{0.25,0.5,0.75,1} press F9 not Enter.
Excel will respond with ={TRUE,TRUE,TRUE,FALSE}
This is showing us that the 1st, 2nd and 3rd elements in the formula: B3>{0.25,0.5,0.75,1}, are True
In our example the value in B3 is 80% which is 0.8 which is Greater than 0.25 and Greater than 0.5 and Greater than 0.75, but Not Greater than 1.0.
The next part of Kyle’s formula is (B3>{0.25,0.5,0.75,1})*0.1
In a blank cell say C7: enter the following:
= B3>{0.25,0.5,0.75,1}*0.1 press F9 not Enter.
Excel will respond with ={0.1,0.1,0.1,0}
This is showing us the result of
=(B3>{0.25,0.5,0.75,1})*0.1
={TRUE,TRUE,TRUE,FALSE} *0.1
={0.1,0.1,0.1,0}
Sumproduct now only has to add up the Array
=Sumproduct({0.1,0.1,0.1,0})
Which it does returning 0.3.
The Neat Part
The neat part of this is that Kyle has used the 0.1 Multiplier to Force the array to an array of Numbers for Sumproduct to sum.
Had Kyle used: =SUMPRODUCT((B3>{0.25,0.5,0.75,1}))*0.1
Excel would have returned an answer of 0
This is because as we saw in Formula Forensics 007, Sumproduct doesn’t know what to do with the array of True/False, they need to be converted to numerical equivalents for Sumproduct to operate on.
In a spare cell, say C9, enter: =SUMPRODUCT((B9>{0.25,0.5,0.75,1}))*0.1
Excel will respond with 0
Of course that can be fixed by using a double degative of a 1* inside the formula
In a spare cell, say C10, enter either:
=SUMPRODUCT(1*(B9>{0.25,0.5,0.75,1}))*0.1
or
=SUMPRODUCT(- -(B9>{0.25,0.5,0.75,1}))*0.1
Excel will respond with 0.3 as it should
Except that the formula is longer and now has to do 1 more multiplication.
Download
You can download a copy of the above file and follow along, Download Here.
Formula Forensics “The Series”
You can learn more about how to pull Excel Formulas apart in the following posts
We Need Your Help
I have received a few more ideas since last week and these will feature in coming weeks.
I do need more ideas though and so I need your help.
If you have a neat formula that you would like to share and explain, try putting pen to paper and draft up a Post like above or;
If you have a formula that you would like explained but don’t want to write a post also send it to Chandoo or Hui.
20 Responses to “Mortgage Calculator with Extra Payments – Excel Download”
Kia ora Chandoo, thanks for this wonderful template brother. How can I modify this/ or do you have a similar template for a fortnightly
payment? Thank you
Morena Rayd. You can adjust the multiplier / divider to 26 (I think it was set to 12) to see fortnightly details. Watch the companion video to understand the steps / logic.
It is very simple and easy to use. Is user interface is attractive. It is very helpful and beneficial for calculations.
This is great, thanks a lot!
I think there is an error in the "You save X $ in interest". If i dont put any extra payment, it still says that I will save 19k in interest rate.
I too realized this problem. I will post an update once I fix the error.
Updated on 11-Sep: I fixed the problem with "interest saved" calculation. Turns out there was an internal bug in cumipmt function in Excel that reports incorrect values. Something new!
Please use the link above to re-download the correct file.
Hi Chandoo, do you have a template that will make changes to figures going forward if the interest rate changes part way through the loan? Thank you for your help.
I wanted calculator which can consider floating interest rate, can you please advise how to get that?
I love your tutorial. If I am making weekly acelerated mortgage payments, how to I account for that in the Eff term?
Thank yo so much,
Christine
Hi Chandoo. I want an excel template where I can have my favourite stocks listed for which the prices changes on a dynamic basis every day as per the market. I mean a sheet which is linked to NSE for price changes and other changes like daily low, Daily high, Yesterday closing, last 10 day range, 52 week high, 52 week low, one month high, one month low, one week high and one week low etc
The excel is awesome but I am getting #NAME? error with the field 'Old Interest Paid' and subsequently Original Interest and Money saved. Can you tell me how to fix that. I am trying to check if I should complete my loan by the extra payments or instead invest the same amount elsewhere
#NAME error could mean your Excel doesn't have one of the functions I am using. Can you tell me what version you are using? If I am not mistaken, this file requires Excel 365.
Hi Chandoo, I am also getting the same error. I am using Office 2019. Would you be able to recommend a fix for this?
Regards,
How do you change the dollar to rupees for whole sheet to match indian currency
You can select the values and apply rupee formatting from cell formatting options.
Hey Chandoo,
Thank you for making the excel spreadsheet! It is great, but there another, little known money saving action that you can take to DRAMATICALLY reduce your total interest owed on your mortgage allowing you to pay it off 40% to 60% faster. I am going to share with you for free. It's called recasting your mortgage, which is a form of re-amortizing the interest that you owe on your loan by paying the the bank an early payment of $10,000 or more. The bank will modify your loan to cancel the original interest that you owe, and recalculate the total interest based on the new lower loan loan amount for the remaining term of the loan, instead of the original loan amount. This pays off the most expensive section of interest on your loan which is the next owed interest, instead of cancelling the interest at the end of your loan. Your charts show the interest being canceled on the last payments, however the interest can be canceled on your next upcoming portion of the loan, but keeps the ending date the same. However, the result of recasting the loan is you, pay the loan off 2 or 3 times faster, by paying off the portion of the loan with the highest interest cost. I am wondering if you can build a excel spreadsheet that shows this for me? I will pay you for making it. I am a mortgage loan officer and would like to use it to help my clients see the impact of paying off their loans this way. Thank you for considering this!
HI Chandoo.
Excellent sheet i watched your video and tried to edit sheet to suit my current mortgage however i cant get it to work. I am trying to set it to weekly payments.
I edited the monthly payments to =PMT(E7/52,E6*52,E5)
eff.term =ROUND(NPER($E$7/52,$E$10,$D13),0)
principal term to =PPMT($E$7/52,1,E13,D13)
cb w/o to =IF(C13=1,$E$5,J12)+PPMT($E$7/52,C13,$E$6*52,$E$5)
and interest paid to =IPMT($E$7/52,1,E13,D13) but i cant edit the arrays to increase the range to 1560 from 360, so i just added the numbers in and that worked for the array on the left but the old interest paid array im stuck. And the graph well the graph is useless now and i have no idea how to fix that. no idea at all.
Any help would be great.
Cheers
To change the NUMBER OF ROWS, go to cell C13 and change the formula to
=SEQUENCE(E6*52)
The chart won't auto-adjust. So you need to adjust the chart's source data range to capture all rows.
Hey man, I really appreciate your contribution, this template is awesome, I am sure it will help me to plane my financial life, and also to pay debts earlier and create wealth.
Thank you!!!
how do i edit this to use months instead of years for term? i have a 90 month loan (7.5 years) that i am trying to use with this and it forces me to use 7 or 8 in years.