Personal Loan Refinance Calculator: Payment and Interest

This personal loan refinance calculator estimates the monthly payment and total interest on a replacement loan from its amount, APR, and term. Enter the proposed loan figures to see the payment and interest estimate; refinancing speed itself depends on the application, lender review, and payoff process.

Formula

The calculator uses a standard fixed-payment loan formula. It divides the amount borrowed by the present value of the scheduled monthly payments, using a monthly rate derived from APR. In symbols:

• Monthly payment = P × r ÷ [1 − (1 + r)⁻ⁿ]
• Total interest = (monthly payment × n) − P
• r = APR ÷ 1,200, the monthly interest rate as a decimal.
• P = new loan principal, in dollars.
• n = loan term in years × 12, the number of monthly payments.
• APR = the annual percentage rate entered, as a percentage.

The formula assumes level monthly payments and a fixed rate. The displayed payment is rounded to cents. The total-interest estimate uses that rounded payment multiplied by the number of payments, so it may differ slightly from a lender’s final schedule, especially if the last payment is adjusted.

Worked Example

Using the defaults—$20,000, an 8% APR, and a five-year term—the calculation is:

1. Convert APR to a monthly rate: 8 ÷ 1,200 = 0.0066667.
2. Find the number of payments: 5 × 12 = 60.
3. Apply the payment formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] = $405.53 per month, rounded to cents.
4. Estimate total interest: ($405.53 × 60) − $20,000 = $4,331.80.

The result is an estimated monthly payment of $405.53 and total interest of $4,331.80 over 60 payments.

Assumptions

• The interest rate remains fixed for the whole term.
• Payments are monthly and made at the end of each period.
• Interest compounds monthly at APR divided by 12.
• The estimate excludes origination or other lender fees, taxes, insurance, and any charges tied to paying off the current loan.

How Quickly Can You Refinance a Personal Loan?

There is no universal turnaround time. A refinance may move from application to funding within a few business days when the application is complete and the lender can verify information quickly. It can take longer if documents are missing, income or identity needs extra verification, the lender has a slower review process, or funds must be sent to the current lender before the old balance is cleared.

“Approved,” “funded,” and “paid off” are different milestones. A lender may approve an application before money is disbursed. If it sends the proceeds to you, you may then need to pay the existing lender yourself. If it sends them directly, allow time for delivery and processing. Continue making required payments on the existing loan until its lender confirms the balance is paid and explains whether any final amount remains due.

What Can Affect the Timeline?

The calendar time depends on steps that vary by lender and borrower. A useful way to think about the process is to separate the application review from the payoff:

• Complete application: Accurate personal, employment, income, and loan details can reduce follow-up requests.
• Verification: A lender may request documents or clarification. Responding promptly does not guarantee an approval or a particular decision time.
• Current payoff information: The balance can change as interest accrues or payments post. Ask the current lender for an official payoff amount and its valid-through date.
• Disbursement and processing: Transfer method, weekends, holidays, and processing at either lender can affect when funds arrive and when the old account is updated.

Ask each lender what its stated review and funding stages mean, what documents it needs, and whether it pays the existing loan directly. Those details are more useful than treating an advertised or estimated processing window as a promise.

How to Compare the Refinance Numbers

A lower monthly payment does not automatically mean a lower overall cost. A longer term can reduce the payment while increasing the number of months interest accrues. For example, extending repayment can make the monthly budget line smaller even when total interest over the full schedule is larger. Compare the proposed loan with the remaining payments on the current loan, using actual figures rather than the original loan’s total cost.

For a fuller comparison, gather the current payoff amount, remaining payment schedule, proposed APR and term, and any fees. The calculator models principal, APR, and term; it does not include fees. If a fee is added to the new balance, use the resulting financed amount as the loan amount to estimate its payment effect, while recognizing that this still does not model every lender charge or timing detail.

Common Delays and Misunderstandings

One common misconception is that approval means the old loan is already closed. It does not: the replacement loan must be funded, the payoff must reach the current lender, and the payment must be posted. Another is that a quoted monthly payment alone shows whether refinancing reduces cost. Term length and fees matter, and a payment estimate cannot predict approval.

Before submitting an application, confirm whether the current loan has a payoff charge or other conditions in its loan documents, and ask the lender for the exact payoff process. Do not stop scheduled payments merely because a refinance is underway. If both lenders are processing around a due date, contact them to clarify responsibilities and keep records of payment confirmations and payoff communications.

Frequently Asked Questions

Can a personal loan refinance be completed in one day?
It is possible for some stages to move quickly, but same-day completion is not guaranteed. Review, verification, funding, and posting the payoff are separate steps, and timing varies.

When should I stop paying my old personal loan?
Keep making required payments until the current lender confirms the loan is paid and tells you the account is settled. A pending application or approval is not proof of payoff.

Does refinancing always lower the monthly payment?
No. The payment depends on the new amount, APR, and term. A longer term can lower a monthly payment but may increase total interest, while fees can add to the amount financed.

Will this calculator tell me whether I qualify?
No. It calculates an estimated payment and interest from the figures entered. It does not evaluate eligibility, lender requirements, or the rate a lender may offer.

What numbers do I need for an accurate comparison?
Use the current loan’s payoff amount and remaining schedule, plus the proposed loan’s APR, term, and fees. Obtain payoff and offer details from the relevant lenders; the calculator does not retrieve them.

This result is an estimate for educational purposes, and the lender’s disclosure gives the exact figures.

Related

• Loan Calculator With Credit Balance: Estimate Payments
• Loan Balance vs Payoff Amount: What’s the Difference?
• Loan Calculator Karmic Balance? Estimate What You Owe

in p | New loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2