How to Calculate Percent of Easy & Practical Loan Interest

How to calculate percent of loan interest with various methods, complete with formulas and examples to better understand installments.

Applying loans to banks or financial institutions can be a solution when you need fast funds, whether for business capital, home renovations, or other urgent needs. But remember, loans always come with interest. This interest is the “money rental fee” that you pay to the lender.

The problem is, many people apply for loans without really knowing how much interest to pay. As a result, installments feel heavy and debt can swell. Well, so you are not stuck, let’s learn how to calculate loan interest and its types.

Also read: Provision Cost: Meaning, Magnitude, and How to Calculate it

Component of calculation of interest percentage

Before understanding how to calculate percent of loan interest, you need to understand the components that affect the amount of installments. Here are the main elements:

1. Tree
   The amount of money borrowed from banks or financial institutions.
   Example: Rp. 20,000,000.
2. Interest rate
   Percentage of loan costs to be paid. Usually stated per year.
   Example: 10% per year.
3. Tenor (time period)
   Length of agreed loan time. Can be in the month or year.
   Example: 12 months (1 year).
4. Type of interest calculation
   There are several methods: flat flowers, effective flowers, floating flowers, and annuity flowers. Each affects the method of calculating installments.

Formula for calculating percent of loan interest rates for its type

In general, there are three types of flowers that are often used: flat flowers, effective flowers, and annuity flowers. Each has a different way to count the installment flowers.

1. FLAT FLOWER

Flat interest means the interest is calculated from the principal of the initial loan and the value remains until the tenor ends. Suitable for short -term loans such as KTA or motorcycle loans.

Flat flower formula:
Interest per month = (loan × annual interest × tenor in the year) ÷ total month

Example:

• Loan: IDR 20,000,000
• Interest rate: 10% per year
• Tenor: 12 months

Interest and Installment Calculation:

1. Total interest = Rp. 20,000,000 × 10% × 1 = Rp. 2,000,000
2. Total Payment = IDR 20,000,000 + IDR 2,000,000 = Rp22,000,000
3. Installments per month = IDR 22,000,000 ÷ 12 = Rp1,833,333

If the tenor is only 6 months:

1. Total interest = Rp. 20,000,000 × 10% × 0.5 years = Rp1,000,000
2. Total Payment = IDR 20,000,000 + IDR 1,000,000 = Rp21,000,000
3. Installments per month = IDR 21,000,000 ÷ 6 = Rp3,500,000

💡 Conclusion: Flat flowers are easily calculated and installments are always the same, but usually the total flowers become bigger than other methods for long tenors.

2. Effective interest

Effective interest is calculated from the remaining principal of the loan. The longer you pay in installments, the remaining staples are smaller, so the flowers are also smaller every month. As a result, total installments will decrease every month.

Effective Flower Formula:
Nn = Moon Flower (Tree N-× Annual Flower Tree) ÷ 12

Example:

• Loan: IDR 12,000,000
• Interest rate: 12% per year
• Tenor: 12 months

Count:

1. Principal installments = IDR 12,000,000 ÷ 12 = Rp1,000,000 per month
2. First Moon Interest = IDR 12,000,000 × 12% ÷ 12 = Rp120,000
   → Total month installments 1 = Rp1,000,000 + Rp120,000 = Rp1,120,000
3. Second Moon Interest = (IDR 12,000,000 – IDR 1,000,000) × 12% ÷ 12 = Rp110,000
   → Total month installments 2 = Rp1,000,000 + Rp110,000 = Rp1,110,000

And so on until paid off, total installments continue to decline.

💡 Conclusion: Fair for the borrower because the flowers are reduced as the remaining debt.

3. Floating flowers (floating)

Floating interest means loan interest rates can change following certain references, such as the BI Rate or market interest rates. Generally used in mortgages after the promo interest period still ends.

Changes in interest rates usually occur regularly, for example every 3 or 6 months.

Floating Flower Formula:
Nn = Moon Flower (Tree N-× Annual Flower Tree) ÷ 12

Example:

• Loan: Rp120,000,000
• Interest rate: First year 6% per year, second year 8% per year
• Tenor: 24 months

Calculation of Installments Year 1:

• Principal installments = IDR 120,000,000 ÷ 24 = IDR 5,000,000 per month
• First Moon Interest = Rp120,000,000 × 6% ÷ 12 = Rp. 600,000

→ Total installment month 1 = IDR 5,000,000 + IDR 600,000 = IDR 5,600,000

Calculation of Installments 2: (for example the main balance of Rp. 60,000,000)

• 13th month interest = IDR 60,000,000 × 8% ÷ 12 = IDR 400,000

→ Total installments of the 13th month = IDR 5,000,000 + IDR 400,000 = IDR 5,400,000

💡 Conclusion: Suitable if the benchmark interest rate tends to go down, because installments can be lighter. However, the risk if the benchmark interest rate rises because the installments also increase.

4. Annuity flowers

Annuity interest is widely used in mortgages. Total installments still Every month, but the composition changes: at the beginning more flowers, approaching the end of more principal.

Annuity Installment Formula:
Installments = Loan Principal × [Suku Bunga per bulan × (1 + Suku Bunga per bulan)^Jumlah Bulan] ÷ [(1 + Suku Bunga per bulan)^Jumlah Bulan – 1]

Example:

• Loan: IDR 12,000,000
• Interest rate: 12% per year (1% per month)
• Tenor: 12 months

Count for fixed installments ≈ Rp1,066,190 per month

Month 1:

• Interest = IDR 12,000,000 × 1% = IDR 120,000
• Tree = Rp1,066,190 – Rp120,000 = Rp946,190

Month 2:

• The remaining principal = IDR 12,000,000 – IDR 946,190 = IDR 11,053,810
• Interest = Rp11,053,810 × 1% ≈ Rp110,538
• Tree = Rp1,066,190 – Rp110,538 ≈ Rp955,652

💡 Conclusion: Installments feel stable, suitable for a consistent monthly budget, but the total interest is usually slightly higher than effective interest.

Why is it important to know how to calculate loan interest?

Before applying for mortgages, vehicle loans, or online loans, you must know how to calculate loan interest per month. That way, you can:

• Estimate monthly installments accurately.
• Determine the right tenor so as not to burden.
• Avoid the risk of failure to pay due to interest that is too high.

If you want to be safer, you can check credit history and credit application opportunities through the application Scorelife. So, before submitting a loan, you already know the possibility of being approved or not.

Also read: Recognize credit restructuring, solutions when unable to pay installments

Tips for managing loans so as not to over budget

Calculating loan interest is important, but managing installments so that it does not pile is equally important. The following tips:

1. Use tenor according to abilityLong installments are small, but the total interest is bigger.
2. Pay on time. Avoid fines that make installments more severe.
3. Monitor all credit & loan cardsSo that nothing is too old, use features Scorpine From SCIRECTLIE. You can check all credit cards, maturity, and analysis of use in one portal.
4. Check credit opportunities approved before applying, first check on Scorelife who have features checking credit opportunities and financial management so as not to waste time if it turns out the opportunity is small.
5. Use Payment & Budget Recommendations featuresLet me know which installments should take precedence.

Conclusion

Understand how to calculate percent of loan interest is not only for calculations, but also a financial strategy. By knowing flat interest, effective, and annuity, you can choose the most suitable type of loan.

If you want to be safer, check the credit score and the opportunity for credit approval first in the Skillife application. You can also monitor all credit cards, manage budget, and get payment recommendations so that finances remain healthy.

That way, loans can be a tool, not a trap that makes a perforated wallet.