Loan Calculator Made by T-K Andy Lau

  This calculator is implemented using JavaScript 1.1, and No CGI is involved. So if your Web-Browser does not support Javascript, this calculator will not work for you, Sorry! The programmer: Andy Lau created this calculator has tested its functions and has satisfied the results. However, Andy Lau and his Web-Server Provider cannot be held responsible for anyone who misuses this program. Please send any comments, questions, or problems of this calculator to the programmer at

To use this calculator, just pick anyone of 4 functional options (1) to (4) at the right-hand column and change the 3 values that you know at the middle of the input areas, your selected option will be computed automatically for you.
Note the Number of Payaments/Year is set to 12. This mean the Interest Rate is in an Annual rate, and Number of Payments = 360 means it is a 30 years loan. Areas (1) to (4) and (6) to (8) are for both input and output. The rests are output areas only. Any input for (6), (7), or (8) will cause area (6) to (11) to be updated and automatically turn on the Amortization Table except option area (8). More operational behavior of this Calculator is listed after the printing area of the Amortization Table.

(1) Loan    Amount        $
 Determine Loan Amount
(2) Interest Rate ( in % ):
 Compute Interest Rate
(3) Amount of Each Payment$
 Compute Amount of Each Payment
(4) Number   of   Payments:
 Compute Number of Payments
(5) Number of Payments/Yr :
 e.g., 12 payments per year.
(6) Additional   Payment  $
 pay to Principal: Loan Amount in (1).
This will pay off the loan sooner.
(7) Monthly      Payment  $
 = (3) + (6).

(8) Loan will be fully paid after 
(9)  with refund of over payment $
 See the table below.
(10) Total Payment of the Loan   $
(11) Total Interest will be paid $

Amortization Table

Note that the table calculations take times; therefore, it is best to turn it Off for speed and turn it on when you want to see the table. However, the results for the options (6) to (9) requires the amortization table calculations. When value in (6) or (7) is changed, amortization table will be turned on automatically.

For the table above, there are 7 columns: 1st is Number of Payment; 2nd & 3nd are Interest Paid and the Accumulated Interest Paid for that period; 4th & 5th are Loan paid from the payment and Additional payment to the principal; 6th is the Accumulated Loan Paid; 7th is the Loan Balance.

Behavior of the Calculator:

Note that a different web browser may behave differently. When a value is entered, the value to be determined will be computed and displayed automatically. Some browsers may show nothing until you click on other input area. So you may need to get use to how this calculator is run on your browser.
The JavaScript: uses double-precision for all the calculations, the final results, specially for the Total Payment and Interest, may not match with the results computed from other software that uses single-precision calculations.
This calculator checks all the input values every time you enter or change anyone of the inputs. When there is problem, an error message will be displayed. Note that changing the numbers in the output areas such as the Total Payment or Interest will cause No actions to the calculator.
When you are ready to see the Amortization Table and trun it On, the On/Off button may disappear for while and reappear after all the calculations are done and displayed at the Table area. Note that if you have a pluge in program running that can eliminates advertisement, i.e., remove additional pop up browser, which may delete the message box from the Javascript to show the Amortization Table is being calculated. When that happens, results may not be shown in the Amortization Table!

Other Andy's Pages
[T-K Andy Lau] [Sidescan Project] [T-Phase Project] [Publications]