A Singapore personal loan calculator that shows your monthly instalment, total interest and a complete amortisation schedule using the effective interest rate (EIR) — the true cost of borrowing that Singapore lenders are required to disclose, not the misleadingly low flat advertised rate.
Why EIR matters
Singapore banks typically advertise a flat interest rate, which sounds like the annual percentage you pay on the original loan amount throughout the tenure. The problem is that you are repaying principal each month, so the actual outstanding balance falls — yet the flat rate charges interest as if it stays constant. The EIR corrects for this, expressing the true annual cost on the declining balance. As a rule of thumb, a flat rate of around 4% is often equivalent to an EIR closer to 7–8%, which is why the MAS mandates EIR disclosure on all personal loan advertisements.
How the instalment is computed
The calculator treats the loan as a fixed-instalment amortising loan. The monthly rate is the EIR divided by 12, and the equal monthly payment is:
M = P * r / (1 - (1 + r)^-n)where P is the amount borrowed, r is the monthly rate and n is the number of months. Each month, interest is charged on the outstanding balance, and whatever is left of the instalment reduces the principal:
interest_m = balance * r
principal_m = M - interest_m
balance = balance - principal_mBecause the balance is largest at the start, early payments are mostly interest and later payments are mostly principal — exactly what the schedule shows.
Worked example
Borrow 20,000 SGD at a 7% EIR over 3 years (36 months). The instalment is about S$617.54 a month, total interest is roughly S$2,231, and you repay around S$22,231 in total.
| Scenario | Loan | EIR | Years | Monthly | Total interest |
|---|---|---|---|---|---|
| Short personal loan | 10,000 | 5% | 2 | ~439 | ~536 |
| Mid-size personal loan | 20,000 | 7% | 3 | ~618 | ~2,231 |
| Larger loan | 50,000 | 9% | 5 | ~1,038 | ~12,264 |
These are illustrative figures — enter your own amounts to see your exact schedule.
Reading the amortisation schedule
The month-by-month table is the most useful part of the output. Early rows show high interest and low principal repayment; later rows flip that ratio. This tells you:
- When to prepay: Prepaying in the first third of the tenure saves the most interest because that is when your balance — and the interest charged on it — is highest.
- How much you still owe: The remaining balance column shows the exact outstanding amount at any point, useful if you receive an early settlement quote from the lender.
- How fees add up: If the lender charges a processing fee, add it to the total interest column to get the true cost comparison across competing offers.
What this tool excludes
Processing fees, late payment charges, annual fees and optional insurance premiums are not included. A real loan may cost a little more than the figures shown. Always request the full cost disclosure (sometimes called the full financial statement) from the lender before signing.
Flat rate vs EIR: the number that actually matters
The gap between the advertised flat rate and the EIR is the single most important thing to understand before comparing loans. A flat rate charges interest on the original amount for the whole tenure, ignoring that you are steadily paying the balance down — so the true cost is always higher than it looks:
| Advertised flat rate | Approximate EIR (typical) |
|---|---|
| 3.5% | ~6.5% |
| 4.0% | ~7.5% |
| 5.0% | ~9.3% |
| 6.0% | ~11% |
The exact conversion depends on tenure and fees, but the direction is always the same: EIR is roughly 1.8-2x the flat rate. This is precisely why the Monetary Authority of Singapore requires lenders to disclose the EIR — and why you should always enter the EIR, not the flat rate, into this calculator.
A note on rate ranges and moneylender caps
The “roughly 3.5-10% EIR” range describes typical bank personal-loan pricing and moves with the interest-rate environment — treat it as a guide, not a quote, and use the actual EIR your lender discloses. Separately, licensed moneylenders are capped by law at 4% interest per month, a completely different (and far more expensive) product from a bank personal loan; check the Registry of Moneylenders if you are borrowing outside a bank.
Sources
- Monetary Authority of Singapore — Understanding effective interest rate (EIR) — the disclosure requirement.
- Ministry of Law — Registry of Moneylenders: interest-rate cap — the 4%/month licensed-moneylender cap.
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