1. Registered User
Join Date
Sep 2007
Posts
60

## Affordability calculator

Hi guys

I'm looking for a calculator script to go within my ASP page that will allow my users to work out how much they can afford. The user simply puts in what they can afford each week along with a down payment and the calculator works out what they can afford.

I have searched the web for around a week and can't find any script examples that do what I need and that I can work from. The closest I have come to a form with everything I need is here:

http://www.tesol.net/scripts/Afforda...fordabilly.cgi

Does anyone know how I can create this calculator in my ASP page?

Any help would be fully appreciated

Best regards

Rod from the UK

2. Given that the formula for interest is: I = Prt
or Interest = Principal x rate x term

What is the formula you are using that incorporates (payment amount) and (payment frequency)?
And how does that relate to the values you are trying to calculate which are assumed to be:
You can afford to borrow \$1,161.89
Interest Rate: 6 %
Loan Length (Term): 1 years
Total interest if paid to term: \$38.11

3. Registered User
Join Date
Oct 2010
Location
Versailles, France
Posts
1,290
See this old (not very handy) page about Prêts à mensualités constantes which give the same result (set the mensualité, taux and durée and click on capital).

But the the lenders are thieves !

They calculate with 6 %/12 = 0.5 % for monthly rate which give an annual real rate of 6,1678 %. With a annual rate of 6%, the real monthly rate should be :
r = (Math.pow (1.06,1/12)-1)/100 = 0.4868 % !

It must be even worse with weekly loans? How do you calculate your weekly rates?
Last edited by 007Julien; 01-25-2014 at 10:45 AM.

4. Registered User
Join Date
Sep 2007
Posts
60
Hi guys

To give you some history, I run a small car website in the UK. My websites allows users to search for cars that I have for same.

What I would like is for my users to use a calculator tool that enables them to find out what car they can afford to buy.

My idea is that they would enter the following data into a form/calculator:

1. What they can afford each month (eg £300)
2. The interest rate of the lender (e.g. 5.6%)
3. The amount they have available to go towards payment (e.g. £5000)
4. The length of time, in months, that they would like to pay their monthly payments

The calculator would then tell them how much they can put towards their next car (e.g. £11,000). So, the user would know that they have a budget of £11,000 and should therefore only search for cars on my website that are priced under £11,000.

I've seen this done in the example link I included in my original thread but I have no idea how they've done it.

Any help would be fully appreciated

Best regards

Rod from the UK

5. Weekly loans 007Julien AKA PayDay loans are calculated on a single month and I have seen average rates from 1,000 to 4,000% interest.

You only need look at companies like cash lady, speedy loans, wonga and others to see just how high interests can be. You will find that it doesn't matter what country you live in, you will have payday loan companies who are backed by some very large investment companies playing the markets and preying on the poorest whilst their main concerns, banks won'r lend a salt bean because the very same people are considered a risk.

They all are nothing but loan sharks and like bankers, need lining up and shooting at the next revolution.

6. Registered User
Join Date
Oct 2013
Posts
1,694
Originally Posted by \\.\
They all are nothing but loan sharks and like bankers, need lining up and shooting at the next revolution.
+1

Although I would add insurance companies to that illustrious list.

7. +100500
shooting is a too simple way for them. i would prefer them to be hanged, drawn and quartered (see some good illustrations http://en.wikipedia.org/wiki/Hanged,..._and_quartered)

8. Registered User
Join Date
Sep 2007
Posts
60
Hi guys

I'm guessing that as I've had no solutions to my calculator script problem that there isn't in fact a solution?

If someone could let me know then that would be great.

Best regards

Rod from the UK

9. I have a solution, but I don't know if the formula is acceptable.

You could use the follow formulas:
I = P x R x T
where I = Interest, P = Principal, R = Rate (%) and T = Term (years)
If Term is to be
a. monthly then, T would be 12 and the R would be R/12
b. weekly then, T would be 52 and the R would be R/52
c. bi-weekly then, T would be 26 and the R would be R/26
with appropriate adjustments to the initial formula.

Typically for simple interest, the amount owed at the end of the term is P + I. Simple.

Your payments, say for a monthly installment, could be calculated as
P = Payment Amount * Term to give the final Principal

Calculate the Interest and SUBTRACT from the Principal.
The interest would be based on the amount agreed to be paid back (payment * term),
but that would NOT be the actual amount generated by the formula before the interest was subtracted.
It would be close for non-extravagant Principals, but would deviate more as the payments increased.
The actual interest rate would not be 5% (for example) but slightly more as in an APR.

If you can provide a better formula for the calculations, the actual calculations would be more accurate.
If you cannot provide a formula for us to use that is acceptable to you, then we are done here.
If the above assumptions are acceptable, then at least attempt a solution for us to discuss.

10. Registered User
Join Date
Sep 2007
Posts
60
Hi JMRKER

Thank you so much for your response - it really is appreciated.

Your formula seems spot on for what I need.

However, I have little or no knowledge about coding in javascript. I was, probably naively, hoping that there was a script out there that I could adopt but I don't think it's going to be as simple as that.

Would you be able to provide (or point me in the right direction of...) the coding for me? If not, I fully understand

I look forward to hearing from you

Best regards

Rod from the UK

11. Registered User
Join Date
Nov 2002
Location
Flint, Michigan, USA
Posts
652
The following link refers to Home Mortgages, but the equations work just as well for other purchases:

http://spruce.flint.umich.edu/~jalarie/jaa_kcg1.htm

I wrote that, so I know the equations. Can I be of service to you?

12. rjoseph, don't mind those jokes about shooting and hanging lol we're here to help people with coding (if we can) so please provide the conditions/equations so that those who are not financier can understand the logic

rjoseph, don't mind those jokes about shooting and hanging lol we're here to help people with coding (if we can) so please provide the conditions/equations so that those who are not financier can understand the logic
I agree and is what I have been asking for since post #2!
As I said, I could make-up a formula but I don't believe it would be as accurate for the larger loans.

14. Registered User
Join Date
Nov 2002
Location
Flint, Michigan, USA
Posts
652
Originally Posted by JMRKER
I agree and is what I have been asking for since post #2!
As I said, I could make-up a formula but I don't believe it would be as accurate for the larger loans.
Check you private messages; I gave you the answer.

This page refers to home mortgages, but the equations work for any loan:

[url]http://spruce.flint.umich.edu/~jalarie/jaa_kcg1.htm

I wrote it, so I know the equations.

15. Sorry, I never received a PM from you
(Yet?)