How To Calculate Loan Interest

Key takeaways

  • Lenders cost two forms of curiosity to earn cash on the quantity borrowed: easy or amortized.
  • Quick-term loans, resembling payday loans and automotive title loans, along with most private loans and federal scholar loans include easy curiosity, whereas mortgages and a few auto loans have an amortization schedule.
  • With each easy and amortized curiosity loans, funds stay the identical over the lifetime of the mortgage. The distinction, nevertheless, is that with an amortization schedule, the portion that goes towards paying curiosity fluctuates all through reimbursement.

Once you take out a mortgage, lenders earn cash by charging you curiosity. Some lenders cost easy curiosity, whereas others cost curiosity based mostly on an amortization schedule.

Apart from the kind of curiosity charged, the general price of your mortgage will even be influenced by different elements, resembling your credit score rating, quantity borrowed and size of the reimbursement time period.

How you can calculate easy curiosity on a mortgage

If a lender makes use of the straightforward curiosity technique, it’s straightforward to calculate mortgage curiosity if in case you have the proper data accessible. You’ll need your principal mortgage quantity, rate of interest and your mortgage time period to be able to calculate the general curiosity prices.

The month-to-month cost is mounted, however the curiosity you’ll pay every month relies on the excellent principal steadiness. So, in case you repay the mortgage early, you might save a large quantity in curiosity, assuming the lender doesn’t cost a prepayment penalty.

How you can calculate easy curiosity

You’ll be able to calculate your complete curiosity through the use of this components:

  • Principal mortgage quantity x rate of interest x mortgage time period = curiosity

For instance, in case you take out a five-year mortgage for $20,000 and the rate of interest on the mortgage is 5 %, the straightforward curiosity components can be $20,000 x .05 x 5 = $5,000 in curiosity.

If you happen to aren’t keen on crunching numbers manually, you should utilize a easy curiosity calculator to run the numbers. Utilizing a calculator can be one of the simplest ways to cut back any calculation errors within the course of.

Who advantages from easy curiosity

Debtors who make on-time or early funds profit from easy curiosity. As a result of curiosity is calculated based mostly solely on the mortgage principal, debtors can save with these loans versus these with compound curiosity.

Sorts of loans that use easy curiosity

Whereas easy curiosity is much less widespread, you would possibly encounter this type of curiosity on short-term loans, resembling payday loans and automotive title loans, in addition to some private loans, automobile loans and mortgages.

These with scholar loans may additionally pay easy curiosity. As an example, all federal scholar loans cost easy curiosity.

How you can calculate amortizing curiosity on a mortgage

Many lenders cost curiosity based mostly on an amortization schedule. This consists of mortgages and a few auto loans. The month-to-month cost on a majority of these loans can be mounted — the mortgage is paid over time in equal installments. Nevertheless, how the lender prices curiosity modifications over time.

The principle distinction between amortizing loans and easy curiosity loans, nevertheless, is that with amortizing loans, the preliminary funds are usually interest-heavy. That signifies that a smaller portion of your month-to-month cost goes towards your principal mortgage quantity.

Nevertheless, as time passes and also you draw nearer to your mortgage payoff date, the desk turns. Towards the top of your mortgage, the lender applies most of your month-to-month funds to your principal steadiness and fewer towards curiosity charges.

How you can calculate amortized curiosity

Right here’s how you can calculate the curiosity on an amortized mortgage:

  1. Divide your rate of interest by the variety of funds you’ll make that 12 months. If in case you have a 6 % rate of interest and also you make month-to-month funds, you’d divide 0.06 by 12 to get 0.005.
  2. Multiply that quantity by your remaining mortgage steadiness to learn the way a lot you’ll pay in curiosity that month. If in case you have a $5,000 mortgage steadiness, your first month of curiosity can be $25.
  3. Subtract that curiosity out of your mounted month-to-month cost to see how a lot in principal you’ll pay within the first month. In case your lender has advised you that your mounted month-to-month cost is $430.33, you’ll pay $405.33 towards the principal for the primary month. That quantity will get subtracted out of your excellent steadiness.
  4. Repeat the method along with your new remaining mortgage steadiness for the next month, and proceed repeating for every subsequent month.

Right here’s the amortization schedule for a $5,000, one-year private mortgage with a 11.91 % rate of interest, which is the typical rate of interest on private loans as of February 2024.

Fee Date Fee Principal Curiosity Whole Curiosity Stability
Oct 2023 $442.65 $395.49 $47.17 $47.17 $4,604.51
Nov 2023 $442.65 $399.22 $43.44 $90.60 $4,205.29
Dec 2023 $442.65 $402.99 $39.67 $130.27 $3,802.31
Jan 2024 $442.65 $406.79 $35.87 $166.14 $3,395.52
Feb 2024 $442.65 $410.62 $32.03 $198.17 $2,984.90
Mar 2024 $442.65 $414.50 $28.16 $226.33 $2,570.40
Apr 2024 $442.65 $418.41 $24.25 $250.58 $2,151.99
Might 2024 $442.65 $422.35 $20.30 $270.88 $1,729.64
Jun 2024 $442.65 $426.34 $16.32 $287.19 $1,303.30
Jul 2024 $442.65 $430.36 $12.29 $299.49 $872.94
Aug 2024 $442.65 $434.42 $8.23 $307.72 $438.52
Sep 2024 $442.65 $438.52 $4.14 $311.86 $0.00

As a result of calculating amortization schedules is pretty math-intensive, Bankrate has a mortgage calculator that does all of the be just right for you. Simply enter the preliminary quantity, the variety of months and the rate of interest and the calculator will provide you with your amortization schedule.

Who advantages from amortized curiosity

Lenders are the first beneficiaries of amortized curiosity. Funds are utilized to each principal and curiosity, extending the size of the mortgage and growing the curiosity paid over time.

Sorts of loans that use amortized curiosity

Many forms of installment loans use amortized curiosity, together with auto loans, mortgages and debt consolidation loans. You may additionally encounter amortized curiosity on house fairness loans.

Elements that may have an effect on how a lot curiosity you pay

Many elements can have an effect on how a lot curiosity you pay for financing. Listed below are some main variables that may affect how a lot you’ll pay over the mortgage life.

Mortgage quantity

The amount of cash you borrow (your principal mortgage quantity) drastically influences how a lot curiosity you pay to a lender. The more cash you borrow, the extra curiosity you’ll pay as a result of it means extra of a threat for the lender.

If you happen to borrow $20,000 over 5 years with a 5 % rate of interest, you’ll pay $2,645.48 in curiosity on an amortized schedule. If you happen to hold all different mortgage elements the identical (e.g., price, time period and curiosity sort) however improve your mortgage quantity to $30,000, the curiosity you pay over 5 years would improve to $3,968.22.


Don’t borrow greater than that you must. Crunch the numbers first and decide precisely how a lot cash you require.

Your credit score rating

Your credit score rating performs a key position in figuring out your mortgage’s rate of interest. Having less-than-perfect credit score sometimes means you’ll get the next rate of interest, as lenders will think about you a much bigger threat than somebody with wonderful credit score.

Constructing on the earlier instance ($20,000, five-year time period, amortized curiosity), let’s examine a 5 % mortgage with a 7 % mortgage. On the 5 % mortgage, the full curiosity price is $2,645.48. If the rate of interest will increase to 7 %, the curiosity price rises to $3,761.44.


It could make sense to enhance your credit score rating earlier than borrowing cash, which may improve your odds of securing a greater rate of interest and paying much less for the mortgage.

Mortgage time period

A mortgage time period is the time a lender agrees to stretch out your funds. So in case you qualify for a five-year auto mortgage, your mortgage time period is 60 months. Mortgages, then again, generally have 15-year or 30-year mortgage phrases.

The months it takes to repay the cash you borrow can considerably affect your curiosity prices.

Shorter mortgage phrases usually require greater month-to-month funds, however you’ll incur much less curiosity since you decrease the reimbursement timeline. Longer mortgage phrases could cut back the quantity that you must pay every month, however since you’re stretching reimbursement out, the curiosity paid might be better over time.


You’ll want to evaluation the numbers forward of time and determine how a lot of a cost you’ll be able to afford every month. Discover a mortgage time period that is smart in your price range and general debt load.

Reimbursement schedule

How usually you make funds to your lender is one other issue to contemplate when calculating curiosity on a mortgage. Most loans require month-to-month funds (although weekly or biweekly, particularly in enterprise lending). If you happen to choose to make funds extra continuously than as soon as a month, there’s an opportunity you might lower your expenses.

Once you make funds extra usually, it will possibly cut back the principal owed in your mortgage quantity quicker. In lots of instances, resembling when a lender prices compounding curiosity, making further funds may save you numerous. Nevertheless, ensure the funds go to paying down the principal.


Don’t assume you’ll be able to solely make a single month-to-month cost in your mortgage. If you wish to cut back the general curiosity you pay to borrow cash, it’s a good suggestion to make funds extra usually than required.

Reimbursement quantity

The reimbursement quantity is the greenback quantity you need to pay in your mortgage every month.

In the identical approach that making mortgage funds extra continuously can prevent cash on curiosity, paying greater than the month-to-month minimal also can lead to financial savings.


If you happen to’re contemplating including cash to your month-to-month mortgage cost, ask the lender if the additional funds will rely towards your principal. If that’s the case, this generally is a nice technique to cut back your debt and decrease the curiosity you pay.

How you can get the perfect mortgage rates of interest

You might be able to enhance your probabilities of acquiring probably the most favorable rate of interest on a mortgage in a couple of methods:

  • Enhance your credit score rating: Essentially the most aggressive rates of interest are usually accessible to these with the very best credit score scores.
  • Go for a shorter reimbursement timeline: The perfect rates of interest will all the time accompany the shortest-term loans. You’ll pay much less curiosity over time in case you can afford the funds.
  • Cut back your debt-to-income ratio: Your debt-to-income (DTI) ratio is the debt you pay every month as a share of your gross month-to-month earnings. It’s almost as vital as your credit score rating when qualifying for a aggressive mortgage.
  • Evaluate affords: Loans aren’t a one-size-fits-all sort of product — every lender has its personal providing. To make sure you get the perfect charges, prequalify with a minimum of three totally different lenders. Prequalifying lets you see the phrases and rates of interest accessible to you with a particular lender with out hurting your credit score.

The underside line

Earlier than taking out a mortgage, it’s very important to calculate how a lot you’ll pay in curiosity to grasp the true borrowing prices. Ask the lender if curiosity is assessed utilizing the straightforward curiosity components or an amortization schedule, and use the suitable components or an internet calculator to run the numbers.

Additionally, be aware of the elements that may have an effect on the curiosity you pay. It could be worthwhile to borrow much less or shorten the reimbursement time period to maintain extra of your hard-earned cash in your pocket. Moreover, it’s best to enhance your credit score rating earlier than making use of and store round to make sure you get the perfect deal on a mortgage.

Share on facebook
Share on twitter
Share on linkedin

Related Posts

Table of Contents

Find our article helpful?

Join our newsletter!

Scroll to Top