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Family mortgage simulation calculator

Calculate monthly mortgage payments, total interest, and the installment-to-income ratio before deciding on a house price.

Input

Rp
%
%

Fixed interest for the first period. Floating interest afterwards can be much higher.

tahun
Rp

Monthly instalment

Rp 7.416.099

180 months, fixed rate 7,5% per year

Down payment20% of the price
Rp 200.000.000
Loan principal
Rp 800.000.000
Total payment
Rp 1.334.897.798
Total interest67% of principal
Rp 534.897.798
Instalment-to-income ratio
37,1%
Costs outside the house price (est. 7%)Transfer tax, notary, provision, appraisal
Rp 70.000.000

A ratio of 37,1% is already heavy. Consider a lower price, a larger down payment, or a longer tenor with the risk of higher total interest.

All calculations run on your device. No numbers are sent or stored.

Assumptions used

  • Annuity formula with fixed interest throughout the tenor — this is a simplification. Real mortgages are usually fixed for 1–5 years then floating.
  • Excludes costs beyond the house price: BPHTB, notary, provision, appraisal, and insurance. Prepare 5–10% of the price.
  • The installment ratio is calculated against monthly income without deducting existing other installments.

How the calculation works

  1. 1Principal debt = house price minus down payment.
  2. 2Monthly installment is calculated using the annuity formula from the principal, monthly interest, and number of months.
  3. 3Total payment = installment times number of months; the difference from the principal is total interest.

Frequently asked questions

What installment ratio is still safe?+

Generally, total installments are allowed up to 30–35% of monthly income. If the calculator flags a number above that, banks are likely to reject or approve with a longer tenor.

Is a long or short tenor better?+

A short tenor saves interest but has larger installments. A long tenor maintains cash flow but total interest can nearly match the principal. Choose one that keeps the installment ratio below 30%.

Why is floating interest dangerous?+

Because after the fixed period, installments can rise without a clear upper limit. While interest is fixed, set aside the difference as a buffer.

Terms in this calculator

collateralAJBAPHTappraisaladmin feeservice charge fee

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Calculator results are educational estimates, not an offer or financial advice.

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