Effective Interest Rate vs Advertised Rate: How to Compare Loan Costs
1/9/26
9 minutes read
By: Joey Chong
Key Takeaways
- The advertised rate is the headline percentage used to describe a loan, while the effective interest rate (EIR) reflects the cost created by the calculation method and repayment schedule.
- A flat advertised rate can look lower than a reducing-balance rate even when the flat-rate loan has the higher effective cost.
- EIR is useful only when comparing loans with similar amounts, tenures and repayment patterns. Also compare the total repayment, instalment amount and fees.
- Application fees, administrative charges and the timing of repayments may affect the effective cost, depending on how the disclosed EIR is calculated.
- For licensed moneylender loans, review the monthly interest rate, permitted fees, actual amount received and completed repayment schedule instead of relying on one converted annual figure.
A low advertised interest rate can make a loan appear inexpensive, but it may not show the full effect of how interest is calculated and when repayments are made. That is why anyone comparing an effective interest rate loan should look beyond the headline percentage.
The effective interest rate, commonly shortened to EIR, supports more consistent comparisons. However, total repayment, fees, instalments, tenure and early-repayment terms also matter.
What Is an Advertised Interest Rate?
The advertised rate is the headline percentage displayed in a promotion, product page or loan illustration. It may also be called a nominal or stated rate.
Check the calculation basis before comparing rates. A flat rate may be applied to the original principal for the entire tenure. Alternatively, interest may be calculated on the outstanding balance as principal is repaid.
The headline rate does not necessarily reveal repayment frequency, fees or deductions. Loans displaying the same rate can therefore have different effective costs.
What Is the Effective Interest Rate on a Loan?
EIR expresses the cost produced by the loan’s cash flows as an annual rate. It considers when money is received and repaid, helping borrowers compare different calculation methods.
According to MoneySense guidance on borrowing costs, the EIR for a flat-rate loan is higher than its advertised rate because interest continues to be based on the original principal even as the borrower repays it. For a monthly-rest loan, interest is calculated on the reduced balance.
EIR is calculated from the money received and scheduled repayments, then annualised. Simply doubling a flat rate will not reliably produce the EIR.
Why Can EIR Be Higher Than the Advertised Rate?
With a flat-rate loan, interest is calculated using the original amount throughout the tenure. Yet each instalment returns principal, so the amount still outstanding falls over time.
Repayment timing also matters. MoneySense illustrates that, for the same principal, total interest and one-year duration, more frequent repayments produce a higher EIR.
Fees can widen the gap. If an upfront charge reduces the cash received while repayments use the full principal, the effective cost increases. Ask which charges are included.
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Flat Rate vs Reducing-Balance Rate
The calculation basis can be more important than the difference between two headline percentages. These are the main distinctions.
| Feature | Flat-rate loan | Reducing-balance loan |
|---|---|---|
| Interest calculation | Based on the original principal throughout the tenure | Based on the remaining principal after repayments |
| Headline rate | May appear comparatively low | May appear higher despite a lower effective cost |
| Effect of principal repayment | Does not reduce the principal used for the flat interest calculation | Reduces the balance on which later interest is calculated |
| Useful comparison figure | EIR, total repayment and fees | EIR, total repayment and fees |
Do not reject a reducing-balance loan merely because its advertised percentage is higher. Compare both offers using their complete repayment schedules.
Worked Example: A Lower Advertised Rate Can Cost More
Consider two illustrative S$10,000 loans repaid over 24 months with equal month-end instalments and no fees. The calculations are rounded, so an actual lender’s disclosure may differ.
| Comparison | Loan A | Loan B |
|---|---|---|
| Advertised rate | 4% per year, flat | 7% per year, reducing balance |
| Monthly instalment | S$450.00 | Approximately S$446.75 |
| Total interest | S$800.00 | Approximately S$722.04 |
| Total repayment | S$10,800.00 | Approximately S$10,722.04 |
| Approximate annual effective rate | 7.76% | 7.00% |
Loan A displays the lower rate, but Loan B has the lower instalment, total interest and approximate EIR. The example shows why comparing “4%” with “7%” without checking the calculation method can produce the wrong conclusion.
Does EIR Include Every Loan Cost?
Not necessarily. Included charges can vary by product. Contingent costs such as late charges are usually absent from a schedule that assumes on-time payment.
EIR cannot predict future variable-rate changes. Promotional loans may also revert from a lower introductory rate to a higher rate.
Ask for the principal, cash disbursed, calculation method, compulsory fees, instalment dates, total repayment and early-settlement terms. Read our guide to understanding loan interest.
EIR vs Total Interest: Which Figure Matters More?
EIR compares annualised costs across different structures. Total interest shows the dollars paid as interest, while total repayment includes principal and applicable amounts in the quotation.
A longer loan may have a lower instalment but greater total interest. A shorter loan may cost less overall but leave too little room for essentials.
The lowest EIR is therefore not automatically suitable. Compare early-repayment fees, variable rates and affordability as well.
How to Compare Loan Costs Step by Step
- Use the same loan amount and tenure. Comparisons become misleading when one quotation covers a different principal or repayment period.
- Identify the calculation method. Confirm whether the rate is flat, monthly rest or another reducing-balance arrangement.
- Record the advertised rate and EIR. Ask how each rate was determined and which fees are included.
- Compare the cash received. Note any permitted upfront deduction or compulsory charge that reduces usable proceeds.
- Add every scheduled payment. Confirm the total repayment using the completed schedule rather than estimating from the headline rate.
- Check flexibility and penalties. Review late-payment, early-settlement, cancellation and rate-reset terms.
- Test affordability. Make sure the instalment fits after essential expenses and existing commitments, including during a weaker month.
A loan calculator can help organise the figures, but its result depends on correct inputs. A calculator using a reducing-balance formula will not accurately model a flat-rate quotation unless it is designed for that method.
Comparing Licensed Moneylender Loan Costs
Licensed moneylender loans in Singapore are governed by specific monthly caps. The maximum interest rate is 4% per month. Late interest is capped at 4% per month and can be charged only on the amount that is overdue. The administrative fee is capped at 10% of principal, while the late fee is capped at S$60 for each month of late repayment.
The total of interest, late interest, the upfront administrative fee and late fees cannot exceed the original principal. These legal limits are ceilings, not quotations and not evidence that a particular loan is affordable.
An annual EIR conversion can be difficult to interpret if it does not exactly reproduce the loan’s monthly cash flows. For a practical comparison, check the actual principal received, every repayment amount and date, all applicable fees and the total payable if payments are made on time. See our detailed guide to licensed moneylender interest rates.
Common Mistakes When Comparing Interest Rates
- choosing the lowest advertised rate without checking whether it is flat or reducing;
- comparing rates for different amounts or tenures;
- ignoring fees deducted before disbursement;
- assuming EIR includes late charges, early-settlement fees or future variable-rate changes;
- focusing on the instalment while overlooking total repayment; and
- using a calculator with a formula that does not match the lender’s method.
Ask for written figures and retain the quotation or repayment schedule. If the explanation does not match the contract, stop and seek clarification before signing.
Frequently Asked Questions
What is an effective interest rate on a loan?
The effective interest rate is an annualised rate based on the loan’s actual cash-flow pattern. It reflects the timing of disbursement and scheduled repayments, making it more useful than a headline rate when comparing different calculation methods.
Why is EIR higher than the advertised rate?
This commonly occurs with flat-rate loans because interest is based on the original principal even as the borrower repays principal. Repayment frequency and certain upfront charges can also increase the effective cost.
Is the loan with the lowest EIR always the cheapest?
Not in every practical sense. EIR supports rate comparison, but borrowers should also examine total repayment, compulsory fees, variable-rate risk, early-repayment penalties and whether the instalments are affordable.
Does EIR include late-payment charges?
EIR usually reflects the agreed repayment schedule rather than costs arising from future missed payments. Confirm what the lender has included and separately review all late-interest and late-fee terms.
Can a loan calculator work out EIR accurately?
Only if the calculator uses the correct cash flows, payment timing, fees and calculation method. Treat the result as an estimate and compare it with the lender’s official quotation and completed repayment schedule.
Compare the Complete Cost, Not One Percentage
The advertised rate is only the starting point. Use EIR to understand the effect of the calculation method and repayment timing, then confirm total repayment, fees and instalments. A transparent comparison should explain where every figure comes from.
Before borrowing, use our responsible borrowing checklist and test the proposed instalment against your budget. If you have reviewed the costs and believe repayment is manageable, you may submit an application for assessment. Approval, amount and terms remain subject to eligibility, verification and the lender’s assessment.
Joey Chong
Joey loves asking questions about why things work the way they do. This trait has served her well. During her decade-long career as a media strategist, she discovered she had a knack for writing and design and continues to employ that to her advantage. She loves watching horror movies on Netflix.
1/9/26
9 minutes read
By: Joey Chong
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