Annual Percentage Rate (APR)
An expression of the effective interest rate the borrower will pay on a loan, taking
into account onetime fees and standardizing the way the rate is expressed. In other words the APR is the total cost of
credit to the consumer, expressed as an annual percentage of the amount of credit granted. APR is intended to make it
easier to compare lenders and loan options.
The APR is likely to differ from the "note rate" or "headline rate" advertised by the lender, due to the addition of other fees that may need to be included in the APR.
In the U.S. and the UK, lenders are required to disclose the APR before the loan (or credit application) is finalized. Credit card companies can advertise monthly interest rates, but they are required to clearly state the annual percentage rate before an agreement is signed. APR is a term used with regard to deposit accounts as well. However, when dealing with deposit accounts, annual percentage yield (APY) or annual equivalent rate (AER) is the number to be quoted to consumers for comparison purposes.
These rates are all equivalent, but to a consumer who is not trained in the mathematics of finance, this can be confusing. APR helps to standardize how interest rates are compared, so that a 10% loan is not made to look cheaper by calling it a loan at "9.1% annually in advance".
The APR does not necessarily convey the total amount of interest paid over the course of a year. APR, in the simple case of a loan with no fees (or, say, a credit card), is the monthly interest rate multiplied by 12.
In the case of a loan with no fees, the amortization schedule would be worked out by taking the principal left at the end of each month, multiplying by the monthly rate and then subtracting the monthly payment. This can be expressed mathematically by:
This also explains why a 15 year mortgage and a 30 year mortgage with the same APR would have different monthly payments and a different total amount of interest paid. There are many more periods over which to spread the principal, which makes the payment smaller, but there are just as many periods over which to charge interest at the same rate, which makes the total amount of interest paid much greater. For example, $100,000 mortgaged (without fees, since they add into the calculation in a different way) over 15 years costs a total of $193,429.80 (interest is 93.430% of principal), but over 30 years, costs a total of $315,925.20 (interest is 215.925% of principal).
In addition the APR takes costs into account. Suppose for instance that $100,000 is borrowed with $1000 onetime fees paid in advance. If, in the second case, equal monthly payments are made of $946.01 against 9.569% compounded monthly then it takes 240 months to pay the loan back. If the $1000 onetime fees are taken into account then the yearly interest rate paid is effectively equal to 10.31%.
The APR concept can also be applied to savings accounts: imagine a savings account with 1% costs at each withdrawal and again 9.569% interest compounded monthly. Suppose that the complete amount including the interest is withdrawn after exactly one year. Then, taking this 1% fee into account, the savings effectively earned 8.9% interest that year.
While the difference between APR and EAR may seem trivial, because of the exponential nature of interest these small difference can have a large effect over the life of a loan. For example, consider a 30year loan of $200,000 with a stated APR of 10.00%, i.e., 10.0049% APR or the EAR equivalent of 10.4767%. The monthly payments, using APR, would be $1755.80. However, using an EAR of 10.00% the monthly payment would be $1691.78. The difference between the EAR and APR amounts to a difference of $64.09 per month. Over the life of a 30year loan, this amounts to $23,070.90, which is over 11% of the original loan amount.
Some classes of fees are deliberately not included in the calculation of APR. Because these fees are not included, some consumer advocates claim that the APR does not represent the total cost of borrowing. Excluded fees may include:
Lenders argue that the real estate attorney's fee, for example, is a passthrough cost, not a cost of the lending.
In effect, they are arguing that the attorney's fee is a separate transaction and not a part of the loan. Consumer
advocates argue that this would be true if the customer is free to select which attorney is used. If the lender insists
on using a specific attorney however, then the cost should be looked at as a component of the total cost of doing business
with that lender. This area is made more complicated by the practice of contingency fees for example, when the lender
receives money from the attorney and other agents to be the one used by the lender. Because of this, U.S. regulators require
all lenders to produce an affiliated business disclosure form which shows the amounts paid between the lender and the
appraisal firms, attorneys, etc.
Lenders argue that including late fees and other conditional charges would require them to make assumptions about the consumer's behavior assumptions which would bias the resulting calculation and create more confusion than clarity.
Consumers can, of course, use the nominal interest rate and any costs on the loan (or savings account) and compute the APR themselves, for instance using one of the calculators on the internet.
The discretion that is illustrated in the "sometimes included" column even in the highly regulated U.S. home
mortgage environment makes it difficult to simply compare the APRs of two lenders. Note: U.S. regulators generally
require a lender to use the same assumptions and definitions in their calculation of APR for each of their products
even though they cannot force consistency across lenders.
With respect to items that may be sold with vendor financing, for example, automobile leasing, the notional cost of the good may effectively be hidden and the APR subsequently rendered meaningless. An example is a case where an automobile is leased to a customer based on a "manufacturer's suggested retail price" with a low APR: the vendor may be accepting a lower lease rate as a tradeoff against a higher sale price. Had the customer selffinanced, a discounted sales price may have been accepted by the vendor; in other words, the customer has received cheap financing in exchange for paying a higher purchase price, and the quoted APR understates the true cost of the financing. In this case, the only meaningful way to establish the "true" APR would involve arranging financing through other sources, determining the lowestacceptable cash price and comparing the financing terms (which may not be feasible in all circumstances). For leases where the lessee has a purchase option at the end of the lease term, the cost of the APR is further complicated by this option. In effect, the lease includes a put option back to the manufacturer (or, alternatively, a call option for the consumer), and the value (or cost) of this option to the consumer is not transparent.
Furthermore, most APR calculators assume that an individual will keep a particular loan until it is completely paid off resulting in the upfront fixed closing costs being amortized over the full term of the loan. If the consumer pays the loan off early, the effective interest rate achieved will be significantly higher than the APR initially calculated. This is especially problematic for mortgage loans where typical loan durations are 15 or 30 years but where many borrowers move or refinance before the loan period runs out.
In theory, this factor should not affect any individual consumer's ability to compare the APR of the same product (same duration loan) across vendors. APR may not, however, be particularly helpful when attempting to compare different products.
Three lenders with identical information may still calculate different APRs. The calculations can be quite complex and are poorly understood even by most financial professionals. Most users depend on software packages to calculate APR and are therefore dependent on the assumptions in that particular software package. While differences between software packages will not result in large variations, there are several acceptable methods of calculating APR, each of which returns a slightly different result.
The calculation for "closeended credit" (such as a home mortgage or auto loan) can be found here. The calculation for "openended credit" (such as a credit card, home equity loan or other line of credit) can be found here.
* Office of the Comptroller of the Currency APR Calculation Software
A single method of calculating the APR was introduced in directive 98/7/EC and is required to be published for the major part of loans. The basic equation for calculation of APR in the EU is:
In this equation the left side is the present value of the draw downs made by the lender and the right side is the present value of the repayments made by the borrower. In both cases the present value is defined given the APR as the interest rate. So the present value of the drawdowns is equal to the present value of the repayments, given the APR as the interest rate.
Note that neither the amounts nor the periods between transactions are necessarily equal. For the purposes of this calculation, a year is presumed to have 365 days (366 days for leap years), 52 weeks or 12 equal months. An equal month is presumed to have 30.41666 days regardless of whether or not it is a leap year. The result is to be expressed to at least one decimal place. This algorithm for APR is required for some but not all forms of consumer debt in the EU. For example, this EU directive is limited to agreements of €50,000 and below and excludes all mortgages.
In the Netherlands the formula above is also used for mortgages. In many cases the mortgage is not always paid back completely at the end of period N, but for instance when the borrower sells his house or dies. In addition there is usually only one payment of the lender to the borrower: in the beginning of the loan. In that case the formula becomes:
If the length of the periods are equal (monthly payments) then the summations can be simplified using the formula for a geometric series. Either way the APR can only be solved iteratively from the formulas above, apart from trivial cases such as N = 1.
* The leaflet Credit charges and APR from the Office of Fair Trading
* The APR and rebate calculator from the Office of Fair Trading
The method used to calculate APRs in the EU and UK is different from that used in the U.S. and will often produce different (higher) results. This is because the U.S. method (regulation "Z") produces what would, in the UK, be called a nominal annual rate whereas the UK/EU method results in an effective annual rate.
The APR is likely to differ from the "note rate" or "headline rate" advertised by the lender, due to the addition of other fees that may need to be included in the APR.
In the U.S. and the UK, lenders are required to disclose the APR before the loan (or credit application) is finalized. Credit card companies can advertise monthly interest rates, but they are required to clearly state the annual percentage rate before an agreement is signed. APR is a term used with regard to deposit accounts as well. However, when dealing with deposit accounts, annual percentage yield (APY) or annual equivalent rate (AER) is the number to be quoted to consumers for comparison purposes.
Rate Format
An effective annual interest rate of 10% can also be expressed in several ways: 
0.7974% effective monthly interest rate 9.569% annual interest rate compounded monthly 9.091% annual rate in advance. 
These rates are all equivalent, but to a consumer who is not trained in the mathematics of finance, this can be confusing. APR helps to standardize how interest rates are compared, so that a 10% loan is not made to look cheaper by calling it a loan at "9.1% annually in advance".
The APR does not necessarily convey the total amount of interest paid over the course of a year. APR, in the simple case of a loan with no fees (or, say, a credit card), is the monthly interest rate multiplied by 12.
In the case of a loan with no fees, the amortization schedule would be worked out by taking the principal left at the end of each month, multiplying by the monthly rate and then subtracting the monthly payment. This can be expressed mathematically by:
Where: 
P_{0} is the initial principal r is the percentage rate used each payment n is the number of payments 
This also explains why a 15 year mortgage and a 30 year mortgage with the same APR would have different monthly payments and a different total amount of interest paid. There are many more periods over which to spread the principal, which makes the payment smaller, but there are just as many periods over which to charge interest at the same rate, which makes the total amount of interest paid much greater. For example, $100,000 mortgaged (without fees, since they add into the calculation in a different way) over 15 years costs a total of $193,429.80 (interest is 93.430% of principal), but over 30 years, costs a total of $315,925.20 (interest is 215.925% of principal).
In addition the APR takes costs into account. Suppose for instance that $100,000 is borrowed with $1000 onetime fees paid in advance. If, in the second case, equal monthly payments are made of $946.01 against 9.569% compounded monthly then it takes 240 months to pay the loan back. If the $1000 onetime fees are taken into account then the yearly interest rate paid is effectively equal to 10.31%.
The APR concept can also be applied to savings accounts: imagine a savings account with 1% costs at each withdrawal and again 9.569% interest compounded monthly. Suppose that the complete amount including the interest is withdrawn after exactly one year. Then, taking this 1% fee into account, the savings effectively earned 8.9% interest that year.
Failings:
Despite repeated attempts by regulators to establish usable and consistent standards, APR does not represent the total cost of borrowing nor does it really create a comparable standard. Nevertheless, it is considered a reasonable starting point for an adhoc comparison of lenders.Does not represent the total cost of borrowing:
Credit card holders should be aware that most U.S. credit cards are quoted in terms of nominal APR compounded monthly, which is not the same as the effective annual rate (EAR). Despite the "Annual" in APR, it is not necessarily a direct reference for the interest rate paid on a stable balance over one year. The more direct reference for the oneyear rate of interest is EAR. The general conversion factor for APR to EAR is:EAR=((1+APR/n)^n)1,
Where: 
n represents the number of compounding periods of the APR per EAR period. E.g., for a common credit card quoted at
12.99% APR compounded monthly, the one year EAR is ((1+.129949/12)^12)1, or 13.7975% (see credit card interest for
the .000049 addition to the 12.99% APR). Note that a high U.S. APR of 29.99% carries an effective annual rate of 34.48%.

While the difference between APR and EAR may seem trivial, because of the exponential nature of interest these small difference can have a large effect over the life of a loan. For example, consider a 30year loan of $200,000 with a stated APR of 10.00%, i.e., 10.0049% APR or the EAR equivalent of 10.4767%. The monthly payments, using APR, would be $1755.80. However, using an EAR of 10.00% the monthly payment would be $1691.78. The difference between the EAR and APR amounts to a difference of $64.09 per month. Over the life of a 30year loan, this amounts to $23,070.90, which is over 11% of the original loan amount.
Some classes of fees are deliberately not included in the calculation of APR. Because these fees are not included, some consumer advocates claim that the APR does not represent the total cost of borrowing. Excluded fees may include:
Routine onetime fees which are paid to someone other than the lender (such as a real estate attorney's fee) Penalties such as late fees or service reinstatement fees without regard for the size of the penalty or the likelihood that it will be imposed. 
Lenders argue that including late fees and other conditional charges would require them to make assumptions about the consumer's behavior assumptions which would bias the resulting calculation and create more confusion than clarity.
Not a comparable standard
Even beyond the nonincluded cost components listed above, regulators have been unable to completely define which onetime fees must be included and which excluded from the calculation. This leaves the lender with some discretion to determine which fees will be included (or not) in the calculation.Consumers can, of course, use the nominal interest rate and any costs on the loan (or savings account) and compute the APR themselves, for instance using one of the calculators on the internet.
In the example of a mortgage loan, the following kinds of fees are:
Generally included: 

Points Prepaid interest Origination fees including loan processing, underwriting and document preparation Attorney and notary fees Closing agent's document preparation fees Private mortgage insurance (PMI) 
Sometimes included: 

Application fees Life insurance 
Generally not included: 

Appraisal Homeinspection Credit report costs Title fee 
With respect to items that may be sold with vendor financing, for example, automobile leasing, the notional cost of the good may effectively be hidden and the APR subsequently rendered meaningless. An example is a case where an automobile is leased to a customer based on a "manufacturer's suggested retail price" with a low APR: the vendor may be accepting a lower lease rate as a tradeoff against a higher sale price. Had the customer selffinanced, a discounted sales price may have been accepted by the vendor; in other words, the customer has received cheap financing in exchange for paying a higher purchase price, and the quoted APR understates the true cost of the financing. In this case, the only meaningful way to establish the "true" APR would involve arranging financing through other sources, determining the lowestacceptable cash price and comparing the financing terms (which may not be feasible in all circumstances). For leases where the lessee has a purchase option at the end of the lease term, the cost of the APR is further complicated by this option. In effect, the lease includes a put option back to the manufacturer (or, alternatively, a call option for the consumer), and the value (or cost) of this option to the consumer is not transparent.
Dependence on loan period
APR is dependent on the time period for which the loan is calculated. That is, the APR for one loan with a 30 year duration loan cannot be compared to the APR for another loan with a 20 year loan duration. APR can be used to show the relative impact of different payment schedules (such as balloon payments or biweekly payments instead of straight monthly payments), but most standard APR calculators have difficulty with those calculations.Furthermore, most APR calculators assume that an individual will keep a particular loan until it is completely paid off resulting in the upfront fixed closing costs being amortized over the full term of the loan. If the consumer pays the loan off early, the effective interest rate achieved will be significantly higher than the APR initially calculated. This is especially problematic for mortgage loans where typical loan durations are 15 or 30 years but where many borrowers move or refinance before the loan period runs out.
In theory, this factor should not affect any individual consumer's ability to compare the APR of the same product (same duration loan) across vendors. APR may not, however, be particularly helpful when attempting to compare different products.
Interestonly loans
Since the principal loan balance is not paid down during the interestonly term, the total interest paid over the lifetime of the loan is increased and the APR is higher than a loan without an interestonly payment period.Three lenders with identical information may still calculate different APRs. The calculations can be quite complex and are poorly understood even by most financial professionals. Most users depend on software packages to calculate APR and are therefore dependent on the assumptions in that particular software package. While differences between software packages will not result in large variations, there are several acceptable methods of calculating APR, each of which returns a slightly different result.
Regionspecific details
United States
In the U.S., the calculation and disclosure of APR is governed by the Truth in Lending Act (also known as Regulation Z). In general, APR in the United States is expressed as the periodic interest rate times the number of compounding periods in a year (also known as the nominal interest rate); since the APR must include certain noninterest charges and fees, however, it requires more detailed calculation.The calculation for "closeended credit" (such as a home mortgage or auto loan) can be found here. The calculation for "openended credit" (such as a credit card, home equity loan or other line of credit) can be found here.
* Office of the Comptroller of the Currency APR Calculation Software
European Union
In the EU, the focus of APR standardization is heavily on the standardization of the timevalue of the interest calculation. As of Oct 2005, the EU still allows Member States to determine the specific costcomponents to be included in the APR calculation.A single method of calculating the APR was introduced in directive 98/7/EC and is required to be published for the major part of loans. The basic equation for calculation of APR in the EU is:
Where: 
M is the number of cash flows paid by the lender l is the sequence number for the cash flows paid by the lender (draw down) Sl is the cash flow (drawdown) in period l N is the total number of cash flows paid by the borrower k is the sequence number of the cash flows paid by the borrower (repayment) Ak is the cash flow (repayment) of period k, and tl and tk is the interval, expressed in years and fractions of a year between the date of the first cash flow and the date of cash flow l or k. (t1 = 0.) 
In this equation the left side is the present value of the draw downs made by the lender and the right side is the present value of the repayments made by the borrower. In both cases the present value is defined given the APR as the interest rate. So the present value of the drawdowns is equal to the present value of the repayments, given the APR as the interest rate.
Note that neither the amounts nor the periods between transactions are necessarily equal. For the purposes of this calculation, a year is presumed to have 365 days (366 days for leap years), 52 weeks or 12 equal months. An equal month is presumed to have 30.41666 days regardless of whether or not it is a leap year. The result is to be expressed to at least one decimal place. This algorithm for APR is required for some but not all forms of consumer debt in the EU. For example, this EU directive is limited to agreements of €50,000 and below and excludes all mortgages.
In the Netherlands the formula above is also used for mortgages. In many cases the mortgage is not always paid back completely at the end of period N, but for instance when the borrower sells his house or dies. In addition there is usually only one payment of the lender to the borrower: in the beginning of the loan. In that case the formula becomes:
Where: 
S is the borrowed amount A is the prepaid onetime fee R the rest debt, the amount that remains as an interestonly loan after the last cash flow. 
If the length of the periods are equal (monthly payments) then the summations can be simplified using the formula for a geometric series. Either way the APR can only be solved iteratively from the formulas above, apart from trivial cases such as N = 1.
UK
APR was introduced under the Consumer Credit Act 1974, to ensure comparability of loans and is required to be published for all regulated loans. The APR must be more prominent than any other rate or charge.* The leaflet Credit charges and APR from the Office of Fair Trading
* The APR and rebate calculator from the Office of Fair Trading
The method used to calculate APRs in the EU and UK is different from that used in the U.S. and will often produce different (higher) results. This is because the U.S. method (regulation "Z") produces what would, in the UK, be called a nominal annual rate whereas the UK/EU method results in an effective annual rate.