How is a Thai personal loan repayment calculated?

Thai personal loans amortise with the standard annuity formula, so each monthly payment is fixed while the interest portion falls as the balance reduces. The tool derives the monthly rate by dividing the annual rate by twelve.

What is the interest rate cap in Thailand?

The Bank of Thailand caps the effective interest rate on personal loans (sinchue bukkon) at 25% per year. Some nano-finance and licensed products can go higher under specific rules, but mainstream personal loans must stay within the cap.

What rates are typical?

Bank personal loans in Thailand commonly run from about 6% to 28% per year depending on income, credit history, and product type. Secured or salary-deduction loans sit at the lower end; unsecured loans sit nearer the cap.

Does the result include fees?

No. The calculation covers interest on the principal only. Stamp duty, processing fees, and insurance premiums are charged separately and raise the true cost above the headline rate, so check the lender's effective rate.

Many Thai lenders allow early settlement, sometimes with a prepayment fee in the first years. Early repayment reduces total interest because interest accrues on the remaining balance, which the amortisation schedule makes clear.

Thailand Personal Loan Calculator

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The Thailand Personal Loan Calculator models the monthly repayment on a Thai personal loan (sinchue bukkon) so you can see the payment and total interest before you borrow. Thai banks typically price personal loans between 6% and 28% per year, and the Bank of Thailand caps the effective rate on mainstream personal loans at 25% p.a.

How it works

The tool amortises the loan with the standard annuity formula. With principal P, monthly rate r (the annual rate divided by twelve) and n monthly payments, the fixed monthly payment is:

M = P × r / (1 − (1 + r)^−n)

Each month the interest charged is balance × r, and the rest of the payment reduces the principal. The schedule below tracks how the split shifts from mostly interest to mostly principal.

Example and notes

Borrowing THB 200,000 over 36 months at 18% per year gives a monthly payment of about THB 7,230 and total interest near THB 60,400. Raising the rate toward the 25% cap pushes both figures up sharply.

This covers interest only — Thai loans also carry stamp duty, processing fees, and sometimes insurance that lift the real cost. Confirm the lender’s effective rate and any prepayment terms.