Loan calculator: payment, interest, and amortization
Quick answer
With the calculator defaults — $50,000 at 18% annual for 3 years (36 months) — the French PMT system returns:
- Monthly payment: $1,807.62
- Total paid: $65,074.31
- Total interest: $15,074.31 (~30% of principal)
Change amount, rate, or term above and the amortization schedule updates instantly. Educational figures only; banks may add fees, insurance, and APR/CAT.
How a loan works (French system)
A loan is an agreement where you receive principal and repay it in periodic installments plus interest. In the French system the payment is fixed: early months are interest-heavy and later months are principal-heavy, because interest is charged on the remaining balance.
Monthly payment formula (PMT)
Payment = P × [r(1+r)^n] / [(1+r)^n - 1]
Where:
- P = principal (loan amount)
- r = monthly rate (annual rate ÷ 12 ÷ 100)
- n = total number of payments (years × 12 + months)
With a 0% rate, payment is simply principal ÷ n.
Hero example: $50,000 at 18% / 3 years
| Item | Value |
|---|---|
| Principal | $50,000 |
| Annual rate | 18% |
| Term | 36 months |
| Monthly payment (PMT) | $1,807.62 |
| Total paid | $65,074.31 |
| Total interest | $15,074.31 |
Near 18% for 3 years, interest in this example tops 30% of principal. Cutting the rate or shortening the term usually saves more than “only watching the payment”.
Rate scenarios ($50,000 / 3 years)
| Annual rate | Monthly payment | Interest | Total paid |
|---|---|---|---|
| 12% | $1,660.72 | $9,785.76 | $59,785.76 |
| 15% | $1,733.27 | $12,397.59 | $62,397.59 |
| 18% (default) | $1,807.62 | $15,074.31 | $65,074.31 |
| 24% | $1,961.64 | $20,619.13 | $70,619.13 |
Short vs long term ($30,000 at 18%)
| Term | Payment | Interest | Total |
|---|---|---|---|
| 2 years (24 mo) | $1,497.72 | $5,945.35 | $35,945.35 |
| 3 years (36 mo) | $1,084.57 | $9,044.59 | $39,044.59 |
| 5 years (60 mo) | $761.80 | $15,708.17 | $45,708.17 |
Stretching from 2 to ~5 years lowers the payment but nearly triples interest in this example.
What is an amortization schedule?
Each month shows payment, principal, interest, and balance. It helps plan early payoffs: extra principal cuts future interest.
Frequently asked questions
With this calculator’s PMT engine: $1,807.62 per month, $15,074.31 interest, and $65,074.31 total — before fees or insurance.
With the PMT formula using principal, monthly rate, and number of payments so the balance reaches zero if every installment is paid on time.
Shorter term = higher payment, less interest. Longer term = lower payment, more total interest. Pick a payment that fits your budget without stretching needlessly.
A fixed payment for the whole loan. Early months are interest-heavy; later months are principal-heavy. It is the most common personal-loan and mortgage schedule.
Usually yes: you cut principal and future interest. Check prepayment fees, then try the early-loan-payoff tool in this cluster.
No. This tool estimates principal + nominal interest only. Bank APR/CAT adds charges; the personal-loan simulator can model opening fees and monthly insurance.