Loan Payment
Mortgage, auto, and personal loan payments
Mortgages, auto loans, and personal loans are all repaid using the exact same formula: a fixed monthly payment that covers accruing interest first and pays down principal with the remainder, until the balance reaches zero at the end of the term. This tool covers all three from one page, because the underlying math never changes — what changes between them is typical rates, typical terms, and what happens if you cannot pay.
Pick a loan type below to load typical defaults for that kind of loan, then adjust the amount, rate, and term to match your actual numbers. All calculations run locally in your browser; nothing you enter is sent anywhere.
What this calculator estimates
- Monthly payment (principal and interest) for a fully amortizing fixed-rate loan.
- Total interest paid across the entire term.
- Total amount paid (principal + interest).
- Amortization schedule showing how each payment splits between interest and principal over time.
None of the three loan types include taxes, insurance, or fees in this base calculation — see the comparison table below for what each one typically adds on top.
The formula — identical across all three loan types
M = P × r(1 + r)^n / ((1 + r)^n − 1)
Where P is the loan principal, r is the monthly interest rate (annual rate ÷ 12, as a decimal), and n is the number of monthly payments (years × 12, or the term in months directly). For a zero-interest loan the formula collapses to P / n. A mortgage, a car loan, and a personal loan plugged into this formula with the same P, r, and n produce the identical monthly payment — the only real differences between the three are what rates and terms are typically available, and what the lender can do if you stop paying.
Worked examples, one per loan type
- Mortgage: $300,000 at 6.5% for 30 years → monthly payment ≈ $1,896; total interest over the term ≈ $382,633 — more than the original principal.
- Auto loan: $22,000 at 6.5% — a 60-month term gives $430.40/month and $3,824 total interest; stretching to 72 months lowers the payment to $369.96/month but raises total interest to $4,637.
- Personal loan: $15,000 at 10.5% — 36 months gives $487.52/month and $2,551 total interest; 60 months gives $322.37/month but $4,342 total interest.
The pattern is the same in every case: a longer term lowers the payment and raises total interest. See The Real Cost of a 72-Month Car Loan for a deeper look at why that trade-off is easy to underweight.
How the three loan types actually differ
| Mortgage | Auto Loan | Personal Loan | |
|---|---|---|---|
| Collateral | The home itself (secured) | The vehicle itself (secured) | Usually none (unsecured) |
| Typical term | 15–30 years | 36–72 months (up to 84) | 24–60 months |
| Typical APR range* | Roughly 6–7% | Roughly 5–9% | Roughly 8–20%+ |
| If you stop paying | Lender can foreclose on the home | Lender can repossess the vehicle | No collateral to seize; lender sues or sends to collections |
| Common add-on costs | Property tax, insurance, PMI, HOA, closing costs | Sales tax, registration, title fees, dealer fees | Origination fee (1–8% of principal), often deducted up front |
*Rates vary significantly by credit score, lender, and market conditions — treat these as rough bands, not quotes, and always compare actual offers.
When to use each type
Use the mortgage mode to compare rate/term combinations before house-hunting — see How Much House Can You Actually Afford for why the payment this calculator gives you and the payment a lender approves you for are not the same question. Use the auto loan mode to check a dealership's numbers against your own before negotiating, and to compare term lengths side by side. Use the personal loan mode to evaluate debt-consolidation offers or financing for a large one-off expense.
What this calculator does not include
All three modes calculate principal and interest only. Real-world costs on top vary by loan type (see the comparison table above) and are not included in the headline payment number — add them yourself once you know your actual rates and local fees. For adjustable-rate mortgages, this tool only models the initial fixed-rate period.
Frequently asked questions
Does this include taxes, insurance, or fees?
No. All three modes calculate principal and interest only. Add property tax/insurance/PMI for a mortgage, sales tax/registration for an auto loan, or origination fees for a personal loan separately — see the comparison table above for typical figures.
Why do mortgage, auto, and personal loans use the same formula?
All three are fixed-rate, fully amortizing installment loans — the math that determines a level monthly payment from a principal, rate, and term doesn't change based on what the loan is for. What differs is typical rates, typical terms, and what the lender can do if you default (see the comparison table).
Should I take a longer term to lower my payment?
A longer term lowers the monthly payment but increases total interest paid, and for auto loans specifically extends how long you're likely to owe more than the vehicle is worth. See the worked examples above and the guide on 72-month car loans for the full trade-off.
Is the amortization schedule accurate?
It applies the standard formula used by US lenders for all three loan types. Real loans may round to the nearest cent each month, which can shift the final payment by a few cents.
Can I pay off any of these loans early?
Most mortgages, auto loans, and personal loans allow extra principal payments or full early payoff without penalty, which reduces total interest. Always check your specific loan agreement for prepayment penalties before assuming this.