Loan Balance Calculator: See What You Still Owe

A loan balance calculator estimates the principal you still owe after a set number of regular payments. Enter the original loan amount, annual APR, loan term, and payments made; the calculator returns the remaining balance, alongside the scheduled monthly payment and total interest for context.

Formula

For a fixed-rate loan with equal monthly payments, the balance after k payments is:

B = P(1 + r)^k − M × ((1 + r)^k − 1) / r

• B is the estimated remaining balance in dollars.
• P is the original amount borrowed in dollars.
• r is the monthly interest rate as a decimal, calculated as APR ÷ 1200.
• k is the number of monthly payments already made.
• M is the monthly payment in dollars, rounded to the nearest cent.

The scheduled payment used here is M = P × r / (1 − (1 + r)⁻ⁿ), where n is the total number of monthly payments (loan term in years × 12). The calculator uses that payment rounded to cents when finding the balance. Its total-interest figure is scheduled payment × number of payments − original amount; it is a full-term estimate, not interest paid so far.

Worked Example

Using the calculator’s default values: an original loan of $20,000, APR of 8%, a five-year term, and 12 payments made:

1. Convert the APR to a monthly decimal rate: 8 ÷ 1200 = 0.0066667.
2. Find the total number of scheduled payments: 5 × 12 = 60.
3. Calculate the monthly payment: $20,000 × 0.0066667 ÷ (1 − (1.0066667)⁻⁶⁰) = $405.53, rounded to cents.
4. Apply the balance formula after 12 payments: $20,000 × (1.0066667)¹² − $405.53 × ((1.0066667)¹² − 1) ÷ 0.0066667 = $16,495.13, rounded to cents.
5. For context, scheduled full-term interest is $405.53 × 60 − $20,000 = $4,331.80.

Assumptions

• The interest rate is fixed throughout the modeled term.
• Payments are equal, made monthly, and applied at the end of each monthly period.
• Interest accrues monthly at APR divided by 12.
• The estimate excludes fees, taxes, insurance, PMI, escrow, missed or late payments, and extra principal payments.

When to Use a Loan Balance Estimate

A balance estimate can help you understand how much principal may remain at a particular point in a loan’s scheduled repayment. For example, it can provide a rough comparison point when reviewing an amortization schedule or checking how much of a fixed payment period has passed. It does not replace the lender’s current payoff quote: the amount needed to close an account on a particular date may include accrued interest, charges, or other adjustments that this calculation does not model.

To use the calculator, enter the original principal—not the total of all future payments—and the APR expressed as a yearly percentage. Enter the term in years and the count of payments already made. The payment count is not the number of years elapsed; if a monthly payment has been made each month for one year, enter 12. The input permits up to 600 payments, while the chosen term determines the scheduled total.

How to Read the Result

The first result is the estimated balance after the stated number of payments. It is not the amount of interest remaining, nor is it necessarily a payoff amount for today. The monthly payment and total interest are supporting figures for the original fixed-term schedule. Total interest assumes every scheduled payment is made as calculated and does not indicate how much interest has already been paid at the selected point.

On an amortizing loan, each payment covers interest accrued for that period and reduces principal by what remains. Early in repayment, a larger share of a level payment generally goes toward interest than later, because interest is calculated on the outstanding balance. Consequently, subtracting the total payments made from the original amount borrowed does not usually give the remaining balance.

Common Sources of Differences

• Payment timing: The formula assumes end-of-month payments. A lender’s accrual conventions or payment dates can produce a different figure.
• Rounding: The payment is rounded to cents, while real servicing systems may apply rounding at each transaction or use more detailed daily accrual.
• Variable rates: If the APR changes, one fixed rate cannot reproduce the full payment history. Use the actual rate history and transaction records for a closer reconstruction.
• Extra or missed payments: Additional principal, late payments, skipped payments, or payment changes alter the balance. The calculator assumes only the stated regular payment schedule.
• Fees and payoff adjustments: Charges, accrued interest since the last payment, and other account-specific items are not included.

A common misconception is that “loan balance” and “payoff amount” always mean the same figure. The modeled balance is principal and scheduled interest arithmetic at a payment boundary; an official payoff amount is a lender-provided figure for a specified date and account.

Frequently Asked Questions

How do I calculate my remaining loan balance?
Use the original principal, monthly interest rate, scheduled monthly payment, and number of payments made in the balance formula shown above. For an account-specific amount, check the lender’s statement or request a dated payoff figure.

Does loan balance mean principal remaining?
In this calculator, yes: it estimates the outstanding loan balance under the stated amortization assumptions. It excludes separate fees and any payoff adjustments.

Why is my balance higher than the original loan minus payments made?
Each payment includes interest. Early payments may reduce principal by less than the full payment, so subtracting all payments from the initial principal ignores the interest portion.

Can I use this for a variable-rate loan?
Only as a simplified estimate if you enter one rate for the entire modeled period. A rate that changed over time requires the actual rates and payment history to estimate the current balance accurately.

Is this the exact amount to pay off my loan?
No. The calculator does not include account-specific charges or interest accrued after a payment date. Ask the lender for a payoff amount tied to the date you intend to pay.

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

Related

• AT&T Trade-In Program: How It Works and What to Know
• Trade-In Value: Calculate Your Loan Equity
• Trade-In Value and Loan Calculator

in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
in k | Payments made | - | 12 | 0 | 600
out bal | Remaining loan balance | $ | p * (1 + apr / 1200) ^ k - (round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2)) * ((1 + apr / 1200) ^ k - 1) / (apr / 1200) | 2
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest over full term | $ | pmt * yrs * 12 - p | 2