how to calculate deposit interest

Learn How to Accurately Calculate Time Deposit Interest!

How to Calculate Deposit Interest – If you often use financial instruments such as time deposits as savings or investments, you're probably curious about how to calculate the interest on the time deposit you receive.

Knowing how to calculate interest is not only for insight or financial addition but also opens opportunities to plan time deposit investment strategies that can yield maximum profit. 

Therefore, this article will explain how to calculate time deposit interest accurately. There are two methods of calculating time deposit interest: based on the total income per maturity and based on the monthly interest profit. Here are the example formulas that can be used.

Also Read: Fixed Deposit: A Beginner's Guide to Starting Investments


How to Calculate Time Deposit Interest Accurately

1. Formula Based on Total Income per Maturity

Principal Deposit + (Profit from Time Deposit Interest – Amount of Time Deposit Tax) 

Before you calculate using this formula, you need to calculate the profit and the amount of time deposit tax. Here are the formulas.

Profit from Time Deposit Interest = (Principal Deposit x Time Deposit Interest Rate x Tenor in days) / 365 (days)
Amount of Time Deposit Tax = Tax Rate x Profit from Time Deposit Interest

So you're not confused, here's an example calculation:

You have a time deposit of IDR 100,000,000, and you deposit it for six months. The time deposit interest rate you receive is 6%, with a tax deduction of 20%.

So,

Interest Profit = (Principal Deposit x Deposit Interest Rate x Tenor)/365
(Rp. 100,000,000 x 6% x 180 days)/365
= Rp. 2,958,904

Amount of time deposit tax = Tax Rate x Interest Profit
   20% x Rp. 2,958,904
= Rp. 591,780

After that, you can calculate the total net profit you get. Use the first formula:

Principal Deposit + (Profit from Time Deposit Interest – Amount of Time Deposit Tax)
= Rp100,000,000 + (Rp2,958,904 – Rp591,780)
= Rp. 102,367,124

In addition, if you want to know the monthly interest profit, it is as follows.

Net Interest in the Period = (Interest Profit – Deposit Tax Amount)/tenor

= (Rp. 2,958,904 – Rp. 591,780)/6 months

= Rp. 394,520

2. Formula Based on Monthly Interest Profit

How to Calculate Deposit Interest

Time Deposit Interest = (Time Deposit Interest Rate x Principal Time Deposit x 30 days x 80%*) / 365 days

*80% is the percentage of income after deducting the tax percentage (100% - 20%).

 So you're not confused, here's an example calculation with the same deposit details as the example above. 

Time Deposit Interest = (Time Deposit Interest Rate x Principal Time Deposit x 30 days x 80%) / 365 days
(6% x Rp. 100,000,000 x 30 x 80%)/365
= 144.000.000/365
= Rp. 394,520

So, the net interest you get per month is Rp394,520.

3. Using the Whiz Simulation Calculator

How to Calculate Deposit Interest

So you're not more confused, now you can simulate the time deposit using the calculator Whiz created specifically for you. You just need to input the total funds you want to deposit and choose the tenor you want. Simple, isn't it?

Check the Whiz simulation calculator here!

Also Read: How to Choose a Deposit Period According to Financial Needs


By using the formulas above, you can estimate the profit you can get from time deposit interest. Make sure to understand the formulas used so that you can calculate time deposit interest accurately.

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