Calculate mortgage per diem interest instantly with this free closing cost calculator. This tool estimates the daily interest on your mortgage loan from closing date through month-end, helping you verify closing costs accurately and understand your true cash-to-close amount.

What Is Mortgage Per Diem Interest?

Mortgage per diem interest is the daily interest charge on your loan from closing date through your first official payment. This interest accrues daily and is collected at closing as part of your total closing costs. Understanding per diem interest helps you accurately budget for closing day and negotiate better terms with your lender.

When you close on a conventional mortgage, your lender funds the loan immediately, but your first monthly payment isn't due for approximately 30 days. The lender charges per diem interest to cover this gap, ensuring they receive compensation for lending you money before you begin regular payments.

For current mortgage rates today, use our updated quotes to compare how interest rates affect your per diem charges and total closing costs.

How Mortgage Per Diem Interest Works at Closing

When you close on a mortgage, your loan funds transfer to the seller, but your first regular monthly payment is typically due on the 1st of the second month after closing. The lender still charges interest during this gap. Per diem interest fills that gap by calculating what you owe on a daily basis.

Practical Example: If you close on the 15th of a month, your first mortgage payment might not be due until the 1st of the following month. Per diem interest covers those 17 days of daily interest charges. The lender adds this charge to your closing costs, and you pay it at the closing table as part of your cash-to-close amount.

This is why choosing your closing date strategically can save you money. Understanding how to calculate per diem interest empowers you to verify your Closing Disclosure for accuracy and negotiate favorable closing dates with sellers.

The Per Diem Interest Calculation Formula

Calculating mortgage per diem interest uses a straightforward mathematical formula that lenders apply consistently:

Per Diem Interest = (Loan Amount × Annual Interest Rate) ÷ Days in Year

Step-by-Step Per Diem Interest Example

Let's assume you borrow $300,000 at 6.5% interest and close on the 15th of the month:

• Step 1: Calculate daily rate: ($300,000 × 0.065) ÷ 365 = $53.42 per day
• Step 2: Count days charged: 17 days (15th through 31st, inclusive)
• Step 3: Calculate total per diem: $53.42 × 17 = $907.14

This $907.14 appears as a line item on your Closing Disclosure. Use our free mortgage per diem calculator above to estimate your specific charge based on your loan details.

When Mortgage Per Diem Interest Appears on Your Closing Disclosure

Per diem interest always appears on your Closing Disclosure, the final document provided three days before closing. This document itemizes all closing costs and the interest charges you'll pay. Most lenders collect per diem interest at closing and include it in your total cash needed to close.

Review your Closing Disclosure carefully to ensure the per diem calculation matches your loan amount, interest rate, and closing date. Some sellers help cover per diem interest as part of seller concessions, though availability varies by market conditions and negotiating strength.

Does Your Closing Date Affect Per Diem Interest?

Yes - significantly. Closing early in a month means more days until your first payment, resulting in more mortgage per diem interest charges. Closing late in the month means fewer days of per diem charges and lower closing costs.

Per Diem Interest by Closing Date

• Close on the 5th: 27 days of per diem interest ($1,440.34 at 6.5% on $300,000)
• Close on the 15th: 17 days of per diem interest ($907.14 at 6.5% on $300,000)
• Close on the 25th: 7 days of per diem interest ($373.94 at 6.5% on $300,000)

Closing on the 25th instead of the 5th saves you over $1,000 in per diem interest charges alone. Many savvy homebuyers strategically schedule closing dates for the last week of the month to minimize this cost. Discuss closing date options with your real estate agent and lender to find the best timing for your situation.

Mortgage Per Diem Interest vs. Your Monthly Payment

Per diem interest is separate and distinct from your regular monthly mortgage payment. Your regular payment begins the month after closing and includes:

• Principal (loan amount repayment)
• Interest (ongoing loan cost)
• Property Taxes
• Homeowners Insurance
• Mortgage Insurance (if applicable)

Per diem interest is a one-time closing cost that appears only on your Closing Disclosure. After closing, you never pay per diem interest again. Understanding mortgage escrow accounts helps clarify how property taxes and insurance are managed in your monthly PITI payment.

Why Mortgage Per Diem Interest Matters to Your Finances

Understanding per diem interest serves several important financial purposes:

1. Budget accurately for total closing costs and cash needed to close
2. Choose an optimal closing date strategically to minimize interest charges
3. Review your Closing Disclosure with complete confidence and accuracy
4. Compare loan estimates from multiple lenders effectively
5. Avoid costly surprises at the closing table
6. Negotiate better terms with sellers regarding concessions

For a complete toolkit of planning resources, visit our mortgage calculators hub to explore payment estimates, affordability calculations, and refinancing analysis tools.

Frequently Asked Questions About Mortgage Per Diem Interest

What is per diem interest on a mortgage?

Mortgage per diem interest is the daily interest charged on your loan from closing date until your first regular payment. It covers the gap between your closing date and the start of your monthly payments. At closing, you pay interest for the remaining days of the month from closing day forward.

How do you calculate per diem interest on a mortgage?

Per diem interest is calculated using the formula: (Loan Amount × Annual Interest Rate) ÷ Days in Year. For a $300,000 loan at 6.5% with 365 days: ($300,000 × 0.065) ÷ 365 = $53.42 per day. Total per diem = daily rate × number of days from closing through month-end.

How many days of per diem interest will I pay at closing?

You pay mortgage per diem interest from your closing date through the end of the month. Close on the 15th = 17 days (15th through 31st). Close on the 25th = 7 days. Closing near month-end reduces your per diem interest charges significantly.

Does using 360 vs 365 days affect my per diem interest?

Yes. A 360-day year produces a slightly higher daily rate than a 365-day year. For a $300,000 loan at 6.5%: 360-day = $54.17/day, 365-day = $53.42/day. Always check which convention your lender uses when calculating mortgage per diem interest.

Is per diem interest included in my closing costs?

Yes, mortgage per diem interest appears as a charge on your Closing Disclosure (CD) and is collected at closing. It's part of your total cash needed to close. The amount depends on your loan amount, interest rate, and closing date.

When does my first mortgage payment start after closing?

Your first regular mortgage payment is typically due on the first day of the second month after closing. If you close in January, your first payment is usually due March 1st. Per diem interest covers interest from January closing through February.

Can I reduce per diem interest by choosing my closing date?

Yes. Closing late in the month reduces mortgage per diem charges because there are fewer days between closing and month-end. Many buyers strategically schedule closings for the last week of the month to minimize this cost.