Finance calculator
Loan Calculator, Monthly Payment, Payoff Date & Total Interest
Calculate monthly payments, total interest, and payoff date for any loan. See the impact of extra monthly payments.
How CalcMesh amortises a loan
A fixed-rate loan payment comes from the standard amortisation formula, which spreads principal and interest evenly across the term. Early payments are mostly interest; later payments are mostly principal.
We build the full amortisation schedule from your amount, rate and term, and show total interest paid; the formula we use is documented in our methodology.
How Loan Interest Works
Loan interest is calculated on the remaining balance each month. With each payment, a portion goes to interest and the rest reduces your principal. This is why your first payments are mostly interest, and your last payments are mostly principal.
Fixed vs. Variable Rates
Fixed rates lock in your interest rate for the entire loan term. Your monthly payment never changes, making budgeting predictable.
Variable rates typically start lower but can adjust periodically. They carry the risk of increasing over time. Consider a fixed rate if you prefer stability.
Tips for Better Rates
- Maintain a credit score above 740 for the best offers
- Shop around and compare at least 3 lenders
- Consider shorter loan terms for lower rates
- Make a larger down payment when possible
- Set up autopay for potential rate discounts
Extra Payment Impact
Making extra payments, even small ones, can dramatically reduce your total interest. For example, adding just $50/month to a $25,000 loan at 6.5% for 5 years saves roughly $500 in interest and pays off the loan 5 months early.
When to Use This Calculator
- Before taking a loan: Compare 3-year vs 5-year terms to understand the payment vs total-cost trade-off.
- Evaluating extra payments: See how adding $100/month changes your payoff date and total interest.
- Auto or personal loan shopping: Plug in each offer to find the true cost of borrowing.
Real-World Examples
Example 1, Auto loan: $35,000, 60 months at 6.9%. Monthly payment: $691. Total interest: $6,484. Adding $100/month extra saves about $980 and pays off 8 months early.
Example 2, Personal loan: $15,000, 36 months at 12%. Monthly: $498. Total interest: $2,936. Shortening to 24 months raises payment to $706 but saves about $990 in interest.
Limitations & Assumptions
- Assumes fixed interest rate for the full term.
- Does not include origination fees, which can add 1-8% to the effective cost.
- Extra payment scenario assumes payments applied immediately to principal.
- Some lenders charge prepayment penalties, check your loan agreement.
Related Guides
- Which Financial Calculator to Use and When - pick the right tool for loans, mortgages, and more
- Understanding Compound Interest - how interest works for and against you
Data Sources
Amortization formula per standard actuarial method. Rate guidance from CFPB and Federal Reserve consumer credit surveys. Actual lender rates vary by credit score, income, and loan purpose.
Methodology & Assumptions
This calculator implements standard formulas drawn from primary-source authorities. Values are point-in-time estimates; consult a licensed professional for high-stakes decisions. See the per-input definitions and source citations below.
How this works
Computations are deterministic and run client-side, no inputs leave your
browser. Formulas are derived from
standard published formulas for the calculator's domain (mortgage,
taxes, energy, conversions, etc.). When the underlying agency publishes
updated rates or thresholds we refresh defaults and update the page's
lastmod timestamp.
| Input | Default | Source / authority |
|---|---|---|
| All inputs | Domain-typical defaults | Editorial methodology, CalcMesh 2026 |