What's effective interest rate (EIR) in personal loans & how do you calculate it?
The Lendela Team
April 8th, 2026
Table of contents
- Unlike annual interest rates, which only gives you a brief idea of how much interest you are paying, EIR takes into account additional factors such as number of instalments, frequency of instalments and the instalment amounts to give you a better idea of the total cost of borrowing.
- EIR makes it easier for borrowers to compare loans from different financial institutions because it puts everything into a more level playing field than annual interest rates.
- Choosing the loan with the lowest EIR is generally a good idea, but you should still consider other factors, such as the total interest payable and the amount of each instalment.
If you compare personal loans using only the advertised rate, you can understate what the loan really costs. In Singapore, effective interest rate (EIR) is the better comparison metric because it reflects the true borrowing cost more clearly than the headline rate alone. It helps you compare loans with different repayment structures, fees, and payment schedules on a more like-for-like basis.
What is an Effective Interest Rate (EIR)?
First, let’s define the meaning of EIR:
Effective Interest Rate (EIR) is the total cost of borrowing a loan, expressed as a percentage of the amount borrowed. Unlike the annual interest rate, EIR takes into account the impact of compounding. While annual interest rates only calculate the percentage of interest applied to the loan amount each year, EIR considers additional factors such as number of instalments, frequency of instalments, and the instalment amounts to give you a better idea of the total cost of borrowing.
Why not just use the Annual Interest Rate?
Financial institutions often advertise their lowest annual interest rates because it's appealing to borrowers. However, borrowers should always look at the EIR for a better idea of the total interest accumulated over time and use it to compare loans from different loan providers.
For example:
Bank A and Bank B might both be offering a personal loan with an annual interest rate of 5%.
However, Bank A might offer a longer loan tenure with more instalments while Bank B might structure the loan differently.
By putting all factors into consideration, EIR makes it easier to compare the cost of two loans and calculate the total cost of borrowing that you are really paying.
Bank | Loan amount | Annual Interest Rate (AIR) | Tenure (months) | EIR |
|---|---|---|---|---|
Bank A | $10,000 | 5% | 24 | 4.7% |
Bank B | $10,000 | 5% | 12 | 5.2% |
Many borrowers assume the annual or advertised rate is enough when comparing loans. It is not. Use EIR as your first comparison filter because it gives a clearer view of the total borrowing cost. Then check:
Monthly repayment
Total payable amount
Processing or admin fees
Early repayment terms
Whether the repayment period still fits your budget
If you want to apply this in practice, compare personalised offers side by side rather than relying on promotional headline rates. Using a loan matching platform like Lendela pulls all your personalised loan offers with all the terms you need to make the best loan decision for your situation.
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How do you calculate EIR?
Banks and financial institutions are required to include additional costs like admin fees in the EIR they calculate for customers. However, to keep things simple, let's look at how EIR is calculated in a scenario where there are no additional fees.
The formula for calculating EIR would be as follows:
EIR = (1 + r/n)^n - 1
Where r is the annual interest rate, and n is the number of compounding periods.
To illustrate with an example: let's say you take out a loan for $10,000 with 12 monthly instalments of $875 each at a 5% annual interest rate. To calculate your EIR, you first divide the annual interest by 12 to get 0.04167%. You then plug this figure into the formula above:
EIR = (1 + 0.04167%/12)^12 – 1 = 5.2%
This means that in total, you will be paying back $10,520 over the course of your loan, resulting in an EIR of 5.2%.
You can save time by using an online EIR calculator, or better yet, use a trusted loan matching platform like Lendela where you can compare and pinpoint out the lowest interest rate personal loan in Singapore within minutes. Since Lendela only partners with reputed licensed banks and loan providers in Singapore, you are sure to avoid loan sharks that prey on unsuspecting clients online.
Should you go for the loan with the lowest EIR?
Generally speaking, going for the lowest EIR is a reliable and cost-effective option. However, borrowers should also take the time to consider other important factors, such as repayment flexibility and loan terms when making their decision.
For example, if you're looking for a loan that can be repaid over a longer period of time, it is better to go for one with a more flexible repayment structure even if its EIR is slightly higher. On the other hand, if you have sufficient cash flow to meet your monthly instalments, then a lower EIR loan may be the most cost-effective option.
Pro tip: Always consider your monthly repayment affordability before finalising a loan. Use budgeting tools or apps to calculate how much you can comfortably repay without compromising other financial goals.
Longer loan equals lower EIR...but more interest overall
It's important to note that a longer loan term usually results in lower EIR, but more interest overall. For example, with the same loan amount and annual interest rate of 5%, if you increase your instalment schedule from 12 months to 24 months, you might see a drop in your EIR from 5.2% to 4.7%. However, even though you're paying less each month over a longer period of time, you’ll be paying more in total over the two-year period due to additional compounding interest applied.
How much can you afford to pay back every month?
Some financial institutions will offer you a lower EIR if your loan has a shorter tenure. However, this usually means a higher monthly repayment, and having to pay back so much money straight away might put you into financial stress. You should also take into consideration of other risk factors, such as the increment of late fees and penalties when you are unable to repay your instalments in full and on time.
What borrowers in Singapore should do with EIR
Use EIR as your first filter, but not your only filter. A good comparison process looks like this:
1. Compare offers on the same repayment period
2. Use EIR/APR first
3. Check monthly repayment
4. Check total payable amount and fees
5. Check early repayment terms
6. Choose the offer whose repayment schedule you can comfortably sustain
If you want to compare offers next, go to compare personal loans. If you want to see how EIR appears inside an actual offer, read our guide to reading a personal loan offer. Want the broader pricing glossary too? Read loan cost & pricing for EIR, advertised rate, APR, fees, and penalties in one place.
Sources
MoneySense: costs of borrowing – https://www.moneysense.gov.sg/costs-of-borrowing-flat-rate-monthly-rest-and-effective-interest-rate/
The Lendela Team
Lendela is a loan-matching platform that partners with 100+ financial institutions. We aim to deliver a transparent, safe, and personalised loan-matching experience, empowering borrowers with confidence to choose what truly fits. Since launching in 2018, we’ve helped hundreds of thousands of Singaporeans make smarter, more informed financial decisions through clarity and control.
