Personal Loan Extra Payments Calculator with Extra Payments
This calculator estimates how making extra payments on a personal loan—either as a single extra payment, a recurring extra each period, or by permanently increasing your periodic payment—affects your payoff date, total interest paid, and number of payments.
Results are modelled using standard amortization formulas under the assumptions listed below. Use the mode selector to switch scenarios and enter either the loan parameters or your actual periodic payment if you prefer.
Add the same extra principal amount each payment starting at a chosen payment number.
Inputs
Advanced inputs
Recurring extra settings
One-time extra settings
Increase payment settings
Results
New total payments (count)
46.1335
Estimated total interest after recurring extras
$1,012.64
Estimated interest saved
$310.10
Estimated payments saved (count)
13.8665
Balance before recurring extras begin
$10,000.00
| Output | Value | Unit |
|---|---|---|
| New total payments (count) | 46.1335 | — |
| Estimated total interest after recurring extras | $1,012.64 | — |
| Estimated interest saved | $310.10 | — |
| Estimated payments saved (count) | 13.8665 | — |
| Balance before recurring extras begin | $10,000.00 | — |
Visualization
Methodology
Calculations use standard fixed-rate amortization mathematics: periodic rate r = annual_rate / payments_per_year, number of periods n = term_years * payments_per_year, and the standard annuity formula to compute periodic payment when not provided by the user.
When an extra payment is applied, the tool computes the remaining balance at the time of prepayment and then solves for the remaining number of periods using the inverse amortization relation. For recurring extras the new payment becomes (regular payment + extra) from the chosen start period onward.
Edge cases: zero interest (r = 0) is handled using linear principal reduction. Results are estimates and assume payments are applied in full on schedule and there are no fees, penalties, or interest-rate changes.
Worked examples
Example: $10,000 loan, 5% annual interest, 5-year term, monthly payments. Adding $50 each month can shorten the term and reduce total interest; the calculator shows new payoff count and estimated interest saved.
Example: Same loan, one-time extra of $500 at payment 12 reduces the remaining balance immediately and shortens the remaining term; the calculator reports the new total interest and payments saved.
Expert Q&A
How accurate are the results?
Results are estimates calculated from standard amortization formulas and are precise for fixed-rate loans with no fees, no prepayment penalties, and when payments are applied exactly as modelled. Actual bank posting rules, rounding, or fees can change exact interest and payoff dates.
Do you account for prepayment penalties or variable rates?
No. This calculator assumes a fixed interest rate and no prepayment penalties. If your loan has penalties, adjustable rates, or special amortization rules, consult your lender and treat these results as estimates only.
Why does the calculator sometimes return fractional payment counts?
The math solves for fractional remaining periods. Most UIs show the fractional result and also round to whole payments for practical planning. The fractional part indicates the final partial payment amount and timing.
Can I enter my actual payment instead of the calculated payment?
Yes. Choose the option to enter your regular payment amount if your lender's payment differs from the standard annuity formula result.
Sources & citations
- NIST - National Institute of Standards and Technology — https://www.nist.gov
- ISO - International Organization for Standardization — https://www.iso.org
- IEEE - Institute of Electrical and Electronics Engineers — https://www.ieee.org
- OSHA - Occupational Safety and Health Administration — https://www.osha.gov