Daily Interest Calculator

Enter your loan principal, annual interest rate, and the number of days since your last payment to calculate your daily interest charge, total accrued interest, and a full day-by-day accrual schedule.

Created by Luis GonzalezLast updated: June 21, 2026

How to Use This Calculator

1
Enter the loan principal
Input the outstanding balance of the loan on which interest will be calculated.
2
Specify the annual interest rate
Provide the annual percentage rate (APR) of your loan.
3
Input days since last payment
Enter the number of days that have passed since your last loan payment was made.
4
Review total accrued interest and schedule
The calculator displays Total Interest Accrued, Daily Interest Charge, Total Amount Owed, Monthly and Annual Interest Equivalents, Period Interest Rate, and Cost per $1,000 Borrowed. The Insights panel shows annual cost projections and payment timing impact.

Example Calculation

An investor wants to calculate the daily interest accruing on a $100,000 loan with a 5% annual interest rate over 25 days.

Loan Principal ($)

100,000

Annual Interest Rate (%)

Days Since Last Payment

Results

Total Interest Accrued

$342.47

Daily Interest Charge

$13.70

Total Amount Owed

$100,342.47

Monthly Interest Equivalent

$410.96

Annual Interest Equivalent

$5,000.00

Tips

Understand compounding frequency

This calculator assumes simple daily interest. For loans with monthly or other compounding periods, the total accrued interest might differ slightly due to the effect of interest earning interest on itself.

Consider loan terms

Some loans (e.g., mortgages) accrue interest daily but compound monthly. Others, like credit cards, might compound daily. Always check your loan agreement for precise terms.

Minimize days between payments

To reduce total interest paid, especially on high-interest loans, aim to make payments as frequently as possible. Paying 10 days earlier on a $100,000 loan at 5% saves $136.99 per cycle.

Understanding Accrued Interest with the Daily Interest Calculator

The Daily Interest Calculator is an essential tool for investors and borrowers to precisely determine the interest that accrues on a loan over a specific number of days. By inputting the principal, annual interest rate, and days since the last payment, users can gain a clear understanding of their financial obligations. For example, a $100,000 loan at a 5% annual rate will accrue approximately $342.47 in interest over 25 days in 2026, significantly impacting the total amount owed.

Impact of Daily Compounding on Investment Returns

While this calculator focuses on daily interest on loans, the principle of daily compounding is equally powerful for investments. Even a small daily interest accrual can lead to substantial gains over time due to the effect of interest earning interest. Many high-yield savings accounts and certain investment vehicles utilize daily compounding, demonstrating how consistent, incremental growth can accelerate wealth accumulation, providing a clear advantage for long-term financial planning.

The Formula for Daily Interest Accrual

The Daily Interest Calculator uses a straightforward formula to determine the amount of interest accrued on a loan. It first converts the annual interest rate into a daily rate, then multiplies this by the principal balance and the number of days elapsed.

Daily Interest Rate = Annual Interest Rate / 365
Daily Interest Charge = Loan Principal × Daily Interest Rate
Total Interest Accrued = Daily Interest Charge × Days Since Last Payment

This calculation provides a precise figure for the interest accumulated over any given period.

💡 For a broader view of investment performance, including the impact of dividends, our Stock Return Calculator with Dividends can help analyze total returns over time.

Calculating Interest on a Short-Term Loan

Consider a borrower with an outstanding loan principal of $100,000 at an annual interest rate of 5%. They want to calculate the interest accrued over 25 days since their last payment.

Calculate the daily interest rate: 5% / 365 days = 0.05 / 365 = 0.0001369863.
Calculate the daily interest charge: $100,000 × 0.0001369863 = $13.70.
Calculate total interest accrued: $13.70 × 25 days = $342.47.

The total interest accrued over 25 days is approximately $342.47.

💡 To evaluate the full impact of an investment over a longer horizon, our Stock Total Return Calculator can show you the comprehensive gains, including price appreciation and dividends.

When Not to Use This Daily Interest Calculator

While highly useful, this Daily Interest Calculator might not be appropriate for all financial scenarios:

Loans with Variable Rates: If your loan's annual interest rate changes frequently (e.g., a variable-rate mortgage or a credit card with promotional rates), using a single annual interest rate will provide an inaccurate result. You would need to calculate interest for each period with its specific rate.
Loans with Irregular Payment Schedules: For loans where payments are not made on a regular, consistent basis, or where additional principal payments are made mid-cycle, the simple "days since last payment" may not fully capture the complex interest accrual. A detailed amortization schedule or direct lender statement would be more accurate.
Investments with Compounding Periods Other Than Daily: While the principle of daily interest applies, this calculator is specifically for accrued interest. For investments that compound monthly, quarterly, or annually, using this tool for "daily interest" on returns will not accurately reflect the growth, as the compounding effect would be different.

Frequently Asked Questions

What is daily interest?

Daily interest is the amount of interest that accrues on a loan's principal balance each day, calculated by dividing the annual interest rate by 365 and multiplying by the outstanding principal. For example, $100,000 at 5% APR accrues $13.70 per day. This method ensures that interest charges accurately reflect the exact number of days money has been borrowed.

How does daily interest impact loan payments?

Daily interest impacts loan payments by continuously increasing the outstanding balance between scheduled payments, meaning a larger portion of your payment goes towards interest if more days have passed. Conversely, making payments earlier in the cycle or more frequently can reduce the total interest paid over the life of the loan, as the principal balance is reduced sooner, lowering subsequent daily interest charges.

Are all loans calculated with daily interest?

No, not all loans are calculated with daily interest. While many common loans like mortgages and personal loans do accrue interest daily, others, such as some installment loans or lines of credit, might calculate interest on a monthly or even quarterly basis. It is crucial to review your specific loan agreement to understand the exact interest calculation and compounding methodology that applies to your debt.

How much does $100,000 cost per day at different rates?

At 4% APR, $100,000 accrues $10.96/day. At 5% APR, it accrues $13.70/day. At 7% APR, it costs $19.18/day. At 10% APR, it reaches $27.40/day. The daily cost increases linearly with the rate — each 1% increase adds $2.74/day on a $100,000 balance.