Loan Calculator
Monthly payments, total interest & amortization
$
%
years
Monthly payment
$—
principal + interest only
Total paid
$—
Total interest
$—
Interest %
—%
📊 Amortization schedule (first & last year)
| Month | Payment | Principal | Interest | Balance |
|---|
Free loan & mortgage calculator — payment, interest, amortization
Toololis Loan Calculator computes fixed-rate loan payments using the standard amortization formula. Works for mortgages, auto loans, student loans, and personal loans. See your monthly payment, total paid over the life of the loan, total interest, and a year-by-year breakdown.
What you get
- Monthly P&I payment — The headline number
- Total paid over loan term — Principal + all interest
- Total interest — How much the loan really costs
- Interest as % of principal — Useful comparison metric
- Amortization schedule — First year + last year, showing how payments shift from mostly-interest to mostly-principal
How to use this tool
- 1
Enter loan amount
Type the total amount you're borrowing (the principal). Works for mortgages, auto loans, personal loans, student loans.
- 2
Set the interest rate
Annual interest rate as a percentage (e.g., 5.5). This calculator uses fixed-rate amortization — the math for standard loans.
- 3
Choose loan term
Length of the loan in years. Common: 30 or 15 for mortgage, 5 for auto, 10 for student.
- 4
Read your monthly payment
The headline number is your monthly payment. Below you'll see total paid over the full term and total interest — often more than the loan itself for long-term loans.
Typical loan types and terms
- 30-year fixed mortgage — Most common in the US. Lower payment, higher total interest.
- 15-year fixed mortgage — Higher payment, ~50% less total interest.
- 5 or 7-year adjustable (ARM) — Fixed rate for initial period, then adjusts. Not modeled here (use fixed rate).
- Auto loan — 3–7 years typical. Shorter = less interest, higher payment.
- Student loan — 10 years standard (US federal). Can extend to 20–25 years.
- Personal loan — 2–7 years. Higher interest than secured loans.
How to save on interest
- Shorter term — A 15-year mortgage vs 30-year saves ~50% of total interest
- Lower rate — Every 1% reduction on a 30-year mortgage saves ~10–15% of total cost
- Extra payments — Any amount above minimum goes 100% to principal, accelerating payoff
- Bi-weekly payments — Paying half your monthly payment every 2 weeks = 13 monthly payments/year = 4–6 years off a 30-year mortgage
- Refinance when rates drop — 1% lower rate on a large loan often pays back closing costs within 2 years
Frequently Asked Questions
How is the monthly payment calculated?
Using the standard amortization formula:
P × (r × (1+r)ⁿ) / ((1+r)ⁿ − 1) where P = principal, r = monthly interest rate (annual ÷ 12), n = total months. Each payment includes principal and interest; the split changes over time.Why do I pay so much more interest than principal in early years?
On a typical 30-year mortgage at 6%, about 80% of your first monthly payment is interest. Over time that flips. The formula charges interest on the remaining balance, which shrinks slowly at first, fast at the end. Use the amortization table to see the shift.
How much does a higher rate cost?
On a $300,000 30-year mortgage: at 5% monthly = $1,610, total interest = $280k. At 7% monthly = $1,996, total interest = $418k. That's $138,000 more interest for a 2% rate difference.
Should I choose a 15-year or 30-year mortgage?
15-year: higher monthly payment, much lower total interest, faster equity buildup. 30-year: lower monthly payment (more cash-flow flexibility), higher total cost. Rule: if you can comfortably afford the 15-year payment, it saves hundreds of thousands in interest.
Can I prepay to save on interest?
Yes — and it's powerful. An extra $200/month on a $300k 30-year mortgage can save $90,000+ in interest and cut 6 years off the term. Check your loan for prepayment penalties (rare in US mortgages, common on personal loans).
Does this include taxes and insurance?
No. This calculator shows the principal + interest payment (P&I). For a full mortgage payment (PITI), add property taxes (usually 1–2% of home value yearly ÷ 12) and home insurance. For loans other than mortgages, P&I is usually the entire payment.
Is this saved anywhere?
No. All calculations happen in your browser. Your loan numbers stay on your device.
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100% Privacy. This tool runs entirely in your browser. Your data is never uploaded to any server.