Car Loan Calculator — Thai Flat Interest

Work out your monthly car or motorcycle installment the way Thai hire-purchase actually works. Enter the vehicle price, your down payment, the flat (add-on) interest rate and the number of months, and the calculator shows the amount financed, total interest, the fixed monthly payment and the total cost. It also estimates the true effective rate, so you can see how a flat quote really compares. Everything runs free in your browser.

Car / vehicle price *

฿

Down payment

฿

Baht (฿) Percent (%)

Enter a baht amount or switch to % of the price. Leave 0 for no down payment.

Flat interest rate (per year) *

Thai hire-purchase quotes a flat (add-on) rate — usually 2%–8% per year.

Loan term *

months

Number of installments, e.g. 12 to 84 months.

Your installment will appear here

Enter the price, flat interest rate and term to see the monthly payment.

Monthly installment

—

Amount financed

—

Total interest

—

Total paid

—

Approximate effective rate (APR)

—

Thai car loans are quoted at a flat rate, but because you repay the balance monthly the true (reducing-balance) rate is roughly 1.8–1.9× higher. Use this effective figure when comparing against a mortgage or personal loan quoted on a reducing balance.

Payment breakdown

Item	Amount

How to use

Enter the car or motorcycle price in baht.
Add your down payment as a baht amount or switch the unit to a percentage of the price.
Enter the flat interest rate per year quoted by the dealer or bank (usually 2%–8%).
Set the term in months, for example 12 to 84.
Read the monthly installment, total interest, total paid and the approximate effective rate instantly.

Features

Thai flat (add-on) interest math used by real hire-purchase contracts
Down payment entered in baht or as a percentage of the price
Fixed monthly installment, total interest and full total cost
Approximate effective (reducing-balance) APR to compare loans fairly
Full payment breakdown you can copy into a note or message
100% in-browser — your figures never leave your device

Frequently asked questions

How is a car loan installment calculated in Thailand?

Thai car loans use flat interest. Total interest = amount financed × flat rate × years, then the monthly installment = (amount financed + total interest) ÷ number of months. On a ฿700,000 loan at 3% flat for 60 months, interest is ฿105,000 and the monthly payment is about ฿13,417.

What is the difference between flat rate and effective rate?

A flat rate is charged on the original loan amount for the whole term, even as you pay it down. The effective (reducing-balance) rate reflects the shrinking balance and is roughly 1.8–1.9× the flat rate. A 3% flat car loan is close to a 5.5%–5.9% effective rate.

Does a bigger down payment lower my installment?

Yes. The down payment reduces the amount financed, and because flat interest is charged on that smaller amount, both your total interest and your monthly installment fall. This tool lets you test any down payment in baht or as a percentage instantly.

Can I use this for a motorcycle loan?

Yes. Motorcycle hire-purchase in Thailand uses the same flat-interest method, usually over 12 to 48 months. Enter the bike price, down payment, flat rate and term and the calculator works out the installment exactly the same way.

Is the calculation done on my device?

Yes. All maths runs in your browser and nothing is sent to a server, so you can compare quotes privately with no sign-up. It is a planning estimate — the final figures in your contract may include fees, insurance or rounding by the lender.