Auto Loan Per Diem Calculator

Formula

To calculate the Per Diem Interest Rate (PDI):

\[ PDI = \frac{I}{365} \]

To calculate the Per Diem Interest Payment Amount (PDP):

\[ PDP = \left( \frac{I}{365} \right) / 100 \times B \]

Where:

$PDI$ is the Per Diem Interest Rate in percentage
$PDP$ is the Per Diem Interest Payment Amount in dollars
$I$ is the Yearly Interest Rate in percentage
$B$ is the Auto Loan Balance in dollars

What is a Per Diem Auto Loan?

A per diem auto loan is a loan structured so that the interest payments are calculated on a per diem basis. With per diem meaning daily in this case. This is a term often used to describe the daily amount someone would theoretically pay on an auto loan interest if that loan happened to require daily payments. (This is almost never the case).

Example Calculation 1

Let's assume the following values:

Yearly Interest Rate ($I$) = 5%
Auto Loan Balance ($B$) = $20,000

Using the formula:

\[ PDI = \frac{5}{365} = 0.013699 \text{ %} \]

\[ PDP = \left( \frac{5}{365} \right) / 100 \times 20000 = 2.74 \text{ dollars} \]

The Per Diem Interest Rate is 0.013699% and the Per Diem Interest Payment Amount is $2.74.

Example Calculation 2

Let's assume the following values:

Yearly Interest Rate ($I$) = 3.5%
Auto Loan Balance ($B$) = $15,000

Using the formula:

\[ PDI = \frac{3.5}{365} = 0.009589 \text{ %} \]

\[ PDP = \left( \frac{3.5}{365} \right) / 100 \times 15000 = 1.44 \text{ dollars} \]

The Per Diem Interest Rate is 0.009589% and the Per Diem Interest Payment Amount is $1.44.