Mortgage Per Diem Calculator
Loan Amount $ Annual Interest Rate (%) Start Date End Date Interest Calculation Basis 365 Days (Actual/365)360 Days (Actual/360) Calculate Reset Per Diem Interest Calculation Number of Days 0 days Daily Interest Rate 0 % Daily Interest Amount $ 0 Total Per Diem Interest $ 0 Monthly Interest Equivalent $ 0 Copy Results When it…
When it comes to closing on a mortgage or paying off your loan early, one term often appears on settlement statements: per diem interest. For many borrowers, it can be confusing.
Simply put, per diem mortgage interest is the amount of interest you owe per day on your loan. Lenders calculate this whenever you close mid-month, make a lump-sum payoff, or refinance.
The Mortgage Per Diem Calculator helps you quickly determine exactly how much daily interest you’ll owe—whether you’re preparing for closing, planning a payoff date, or just budgeting smarter.
What Is Mortgage Per Diem Interest?
The term per diem comes from Latin, meaning “per day.” In mortgages, it refers to daily accrued interest.
Here’s how it works:
- Mortgages are billed monthly, but interest accrues daily.
- If you close on your home mid-month, you’ll prepay interest from your closing date until the first payment is due.
- If you pay off your loan early (e.g., refinance or sell), you must cover per diem interest from your last payment to the payoff date.
Why Use a Mortgage Per Diem Calculator?
Per diem interest can sneak up on borrowers who aren’t prepared. The calculator ensures you:
- ✅ Know how much daily interest accrues on your loan.
- ✅ Plan exact payoff dates to avoid paying extra.
- ✅ Understand closing costs in advance.
- ✅ Budget properly for early repayments or refinancing.
- ✅ Negotiate more confidently with lenders.
How to Use the Mortgage Per Diem Calculator
Using the tool is straightforward. Here’s a step-by-step guide:
- Enter Loan Amount
- Example: $300,000.
- Enter Interest Rate
- Your current annual mortgage interest rate (e.g., 6%).
- Select Loan Start Date (or last payment date)
- This helps calculate accrued interest up to the payoff date.
- Enter Payoff/Closing Date
- The exact date you plan to close or pay off.
- Click Calculate
- Instantly see per diem interest, total interest due, and payoff balance.
Practical Example
Scenario:
- Loan Balance: $300,000
- Interest Rate: 6% annually
- Loan accrues daily interest = (0.06 ÷ 365) × 300,000 = $49.32 per day
If closing is scheduled for the 20th of the month, you’ll owe:
- 10 days × $49.32 = $493.20 in per diem interest at closing.
👉 This amount is added to your closing costs so your first mortgage payment starts fresh on the following due date.
Benefits of the Mortgage Per Diem Calculator
- Transparency – No more guessing what lenders are charging daily.
- Smart Timing – Pick the right closing or payoff date to minimize interest.
- Budget Accuracy – Avoid surprise costs at settlement.
- Early Payoff Planning – Know exactly how much to set aside.
- Confidence in Refinancing – Understand accrued interest before switching loans.
Use Cases
- Homebuyers preparing for closing.
- Refinancers calculating payoff amounts.
- Home sellers paying off a loan before transferring ownership.
- Borrowers making lump-sum payments toward principal.
- Financial planners helping clients manage payoff strategies.
Tips for Borrowers
- Closing at the end of the month minimizes prepaid interest.
- Always confirm whether your lender calculates per diem on a 360-day or 365-day year.
- Remember: mortgage payments are paid in arrears (covering the previous month’s interest).
- Use the calculator before committing to a closing date to see how costs shift.
- If paying off early, double-check with your lender for the exact payoff quote.
Frequently Asked Questions (FAQ)
1. What is a mortgage per diem calculator?
It’s a tool that calculates daily mortgage interest based on loan balance, interest rate, and payoff/closing date.
2. How is per diem mortgage interest calculated?
Divide annual interest by 365 (or 360) and multiply by loan balance.
3. Why do lenders charge per diem interest?
Because interest accrues daily, and your payment schedule may not align with your closing or payoff date.
4. Is per diem interest the same as prepaid interest?
Yes, at closing, the prepaid interest you pay is essentially per diem interest.
5. Can I avoid paying per diem interest?
Not entirely—it’s always due for the days you borrow. But you can minimize it by closing near month-end.
6. How does per diem interest affect refinancing?
You’ll owe per diem interest from your last payment until the refinance closes.
7. How much is daily interest on a $200,000 loan at 5%?
About $27.40 per day (200,000 × 0.05 ÷ 365).
8. Do all lenders use 365 days to calculate?
Not always—some use a 360-day year, which slightly increases daily interest.
9. Why does closing date matter for per diem interest?
The earlier in the month you close, the more prepaid interest you owe upfront.
10. Is per diem interest tax-deductible?
Yes, as part of mortgage interest paid (consult a tax advisor).
11. What happens if I close on the 1st of the month?
You’ll owe nearly a full month’s prepaid interest.
12. What if I close on the 30th?
You’ll owe just 1 day of prepaid interest.
13. Does per diem interest change monthly?
Yes, it’s based on your current loan balance, which decreases over time.
14. How do extra principal payments affect per diem?
They reduce your balance, lowering future daily interest charges.
15. Can sellers cover per diem interest?
No, per diem is the borrower’s responsibility—it’s tied to your loan.
16. Is per diem interest included in my monthly mortgage payment?
Not directly—it’s usually prepaid at closing or added to a payoff.
17. Why do lenders sometimes show odd payoff amounts?
Because per diem interest is added up to the exact payoff date.
18. Can I use the calculator for commercial loans?
Yes, as long as you know the balance, rate, and per diem method.
19. Does per diem interest affect escrow?
No, escrow accounts cover taxes and insurance, not interest.
20. Why use a calculator instead of asking the lender?
It gives you an independent estimate to compare against the lender’s payoff quote.
Final Thoughts
The Mortgage Per Diem Calculator is a must-have tool for anyone navigating closing, refinancing, or early payoff. By showing your exact daily interest cost, it helps you:
- Budget for settlement with no surprises.
- Choose the most cost-effective closing date.
- Plan loan payoffs more strategically.