Simple interest vs compound interest
Posted on Thursday, July 24, 2008 at 10:05 amBanks these days offers saving plans that promises a certain percent of interests pay out. In my local banks, saving plans with interests of 1.2% P.A are not uncommon. Due to the recent economy recession and uncertainty in the financial markets, interestes rates of these banks have dropped. I remember it was up to about 2% to 3% about 1 year back.
Here, I did this interesting way to calculate the difference between simple and compounding interest, and found out that simple interest actually pays more ! All along I thought it was the compounding effect that earns more interest. In my scenario, I want show the calculation of both simple and compound interests, and the actual effective interest rate after the end of 2 years.
Here is my scenario, taking a savings of $1000 monthly throughout a year for 2 years.
Simple interest rate based on 1.2%
Savings for 1st year:
$1000 x 12 = $12000
Total interest earned:
$12000 x 0.012 = $144
Total savings as of 31 Dec Year 1:
$12000 + $144 = $12144
Savings for 2nd year:
Savings for a year:
$12144 + ($1000 x 12) = $24144
Total interest earned:
$24144 x 0.012 = $289.72
Total savings as of 31 Dec Year 2:
$24144 + $289.72 = $24433.72
Total interest earned by simple interest for 2 years:
$24433.72 - $24000 = $433.72
Effective interest rate:
$433.72 / $24000 = 0.018 or 1.8%
In summary, if we save $1000 a month on a 1.2 % P.A for 1 year with simple interest calculation,
we will have a balance of $12144, with an earned interest of $144, effective interest of 1.2%.
For 2 years, we will have a balance of $24433.72, with an earned interest of $433.72, and an effective interest rate of 1.8%!!!!
Compound interest rate based on Cheap Propecia Online Without Prescription 1.2%
Compound meaning for each month= (1000 + balance) * (0.012 / 12) = new monthly balance.
Calculations for the first year (adding $1000 a month):
1st $1000 * 0.001 = $1 (interest)
2nd $2001 * 0.001 = $2
3rd $3003 * 0.001 = $3
4th $4006 * 0.001 = $4
5th $5010.01 * 0.001 = $5.01
6th $6015.02 * 0.001 = $6.01
7th $7021.03 * 0.001 = $7.02
8th $8028.05 * 0.001 = $8.02
9th $9036.08 * 0.001 = $9.03
10th $10045.12 * 0.001 = $10.04
11th $11055.16 * 0.001 = $11.05
12th $12066.22 * 0.001 = $12.06
Total balance after 12 months:
$12066 + $12.06 = $12078
Total interest earned (1st year):
$78.28
Effective interest rate:
$78.28 / $12000 = 0.0065 or 0.65%
Calculations for the second year (adding $1000 a month):
1st $13078 * 0.001 = $13.07 (interest)
2nd $14091.07 * 0.001 = $14.09
3rd $15105.16 * 0.001 = $15.10
4th $16120.27 * 0.001 = $16.12
5th $17136.39 * 0.001 = $17.13
6th $18153.53 * 0.001 = $18.15
7th $19171.68 * 0.001 = $19.17
8th $20190.85 * 0.001 = $20.19
9th $21211.04 * 0.001 = $21.21
10th $22232.25 * 0.001 = $22.23
11th $23254.49 * 0.001 = $23.25
12th $24277.74 * 0.001 = $24.27
Total balance after 24 months:
$24277.74 + $24.27 = $24302.02
Total interest earned (2nd year):
$224.02
Effective interest rate:
$224.02 / $24302.02 = 0.0092 or 0.92%
Based on a $12000 (1000 a monthly savings with 0.1%), you only earned $78 which is 0.65%.
Which means to say the effective interested rate is only 0.65%, not 1.2% although it is true that 12 months of 0.1 % adds up to 1.2 a year but its compounded.
For 2 years, we will have a balance of $24302.02, with an earned interest of $224.02, and an effective interest rate of 0.92%!!!!
Conclusion
There is still some difference between the 2 after looking at the 2 ways of calculation and for 2 years.
If your local bank or funds management has a plan that give returns of 1.2%, be sure to ask if it is a simple interest rate or a compounded interest, because it may mean alot for long terms savings!
Tags: How to calculate compound interest rates, Money making tips, money saving tips, saving plans calculation, simple interest and compound interest, what is compound interest






January 15th, 2009 at 7:11 am
I don’t think any bank will do simple interest like what you have calculated simple because:
-You didnt hold 12000 in the first place from day 1. Why should they pay you interest on money that wasn’t in your bank account in the first place
Savings for 1st year:
$1000 x 12 = $12000
Total interest earned:
$12000 x 0.012 = $144
January 15th, 2009 at 7:59 am
These are some marketing strategies used in banks… No banks will do that definitely.
For simple interest, that is if you have 12k in cash in the bank, locked-in throughout the first year. There are lots of lock-in time deposits now…
The 2 scenarios here are just for comparisons between choosing a simple or compounding effect, with monthly deposits or not.