Calculate daily equated installment payments, total interest, payoff date, and amortization schedule for loans with extra payments.

Equal end-of-period payments on a reducing balance.

Use the contract interest rate. Fees included in an APR are not modeled.

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Equated Daily Installment Formula

The following formula is used to calculate the equated daily installment for a given principal amount, daily interest rate, and number of days.

EDI = (P × r × (1 + r)ⁿ) / ((1 + r)ⁿ - 1)

Variables:

  • EDI is the equated daily installment
  • P is the principal amount
  • r is the effective rate per payment period, as a decimal (daily when daily payments are selected)
  • n is the number of payment periods (days for daily payments)

For a positive period rate, use the formula above. At zero interest, installment = P/n. The calculator converts the nominal annual contract rate to the selected payment period; fees included in an APR are excluded. Rounded regular payments may require an adjusted final payment.

What is an Equated Daily Installment?

An equated daily installment (EDI) is a fixed amount paid daily to repay a loan over a specified period. It includes both the principal and the interest components, ensuring that the loan is paid off in equal daily installments. This method is commonly used in microfinance and short-term loans where daily repayments are more manageable for borrowers.

How to Calculate Equated Daily Installment?

The following steps outline how to calculate the Equated Daily Installment.

  1. First, determine the principal amount (P).
  2. Next, determine the daily interest rate (r).
  3. Next, determine the number of days (n).
  4. Finally, calculate the Equated Daily Installment using the formula EDI = (P * r * (1 + r)^n) / ((1 + r)^n – 1).
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Principal Amount (P) = $1000

Daily Interest Rate (r) = 0.05%

Number of Days (n) = 30. With a daily rate of 0.05% (decimal 0.0005), the unrounded installment is approximately $33.5922905; a regular payment rounded to cents is $33.59, with the final payment adjusted.