Loan Calculator
Estimate monthly payments, total interest and payoff plans.
How to use
- Enter the loan amount, the annual interest rate (%) and the term in years (decimals allowed): results update live as you type.
- The term is entered in years: 20 years means 240 installments, and 1.5 years is converted to 18. The tool uses the equal-payment (annuity) method, so the monthly amount is fixed.
- The results show the monthly payment, the total repayment and the total interest. The "Repayment split" row and its bar visualize how much of the total repayment goes to principal versus interest: a larger interest share means a more expensive loan.
- With a 0% annual rate, the monthly payment is simply the principal divided by the number of installments and the bar is 100% principal.
- Out-of-range or invalid inputs show a red error message; click "Copy result" to copy all figures at once.
FAQ
What does "equal payment" (等额本息) mean?
What is the difference from equal-principal (等额本金) loans?
Why may the result differ slightly from my bank statement?
Can the interest rate be 0?
How to use
- Enter the loan basics
Fill in the loan amount (greater than 0), the contract annual rate (0-100%) and the term in years. Decimals like 1.5 are allowed, up to 50.
- Know the payment model
The tool uses the equal-payment annuity method: M = P × r × (1+r)^n ÷ ((1+r)^n - 1). Here r is the monthly rate (annual ÷ 12) and n is the number of installments.
- Read the three totals
The result box shows the fixed monthly payment, total repayment and total interest, refreshing live as you type. Different parameters compare instantly.
- Check the principal split
The repayment-split row and its bar show how the total divides into principal and interest. A larger interest share means a costlier loan.
- Compare offers quickly
Change the rate or term to see the payment move at once. Click Copy result to save all four figures for comparing bank offers side by side.
About this tool
This loan calculator implements the annuity (equal-payment) method. Every monthly installment is identical, and its principal share rises while the interest share falls over time. The formula is M = P × r × (1+r)^n ÷ ((1+r)^n - 1). Here P is the principal, r is the monthly rate (annual rate ÷ 12) and n is the number of installments (years × 12). At a 0% rate the payment reduces to principal ÷ installments.
Use it to budget a mortgage, car loan or consumer loan and to compare lender quotes. A 300,000 loan at 4.9% over 20 years costs roughly 1,963 per month. Shortening the term or shaving 0.1 points off the rate shows the savings in total interest right away. Alongside the payment you get total repayment, total interest and the principal-interest bar. These are planning estimates only, since real statements vary slightly.
How it works
The monthly-payment formula encodes one equivalence: discount every installment back at the monthly rate, and the sum must equal the principal. Solving that single equation yields the fixed payment. Interest is settled first, so early installments lean heavily toward interest. On a 300,000 loan at 4.9% over 20 years, month one carries about 1,225 of interest against roughly 738 of principal. The two shares do not flip until around installment 70. This asymmetry explains why early prepayments save the most interest. It also explains why shortening the term beats shrinking the payment when total cost is the goal.
A contract rate is nominal. Compounded monthly, 4.9% a year works out to an effective (1+4.9%/12)^12 - 1 ≈ 5.012%. Comparing offers also demands a common basis. Appraisal, guarantee and prepayment-penalty fees all raise the true price of money. That is why the regulated total-cost figure usually exceeds the headline rate. Feed competing quotes into the calculator at the same amount and term. Then read total interest and monthly payment together: quotes whose payments differ by a few dozen can differ by tens of thousands in interest. Once the rate basis is aligned, what remains is the trade-off between term and amount.
When to use it
- Comparing two lender quotes
Run the same amount and term once per lender and copy each result. Quotes whose payments differ by a handful can span thousands in total interest. Laying the two strings side by side gives the negotiation an anchor.
- Planning an early payoff
Shorten the term to the remaining months and recompute, then compare the total-interest fall. Penalties and the installments already paid trim the real gain. Subtract them first; the remainder is the floor worth taking to the bank.
- Sizing the payment to income
Lending practice treats one third of household income as the payment ceiling. Fix the down payment, then try terms until the payment slides under that line. Watch how total interest balloons with every year you add.
Tips & tricks
- Equal payments are easy to budget. Equal-principal plans usually cost less interest but start heavier each month.
- Bank statements can differ slightly because of disbursement dates, interest-day counting rules, fees and early repayments.
- Inputs outside a 0-100% rate or a 50-year term raise a red error. Fixing them recalculates at once.
Things to watch
- Nominal is not the real cost
Monthly compounding lifts the effective annual rate above the nominal one; 4.9% works out near 5.01%. Fees belong in the same comparison. Judging loans by headline rates alone understates what borrowing truly costs.
- Interest-first products differ
Interest-only structures pay interest monthly and the principal at maturity. They cost more overall and end with a lump-sum wall. This tool models equal payments, so never line its figures up against such products directly.
- The payment is not the whole bill
Mortgages carry deed taxes, maintenance funds, insurance and management fees. Car loans add registration and tracking charges. Budget those beside the calculator's payment, or cash flow tightens the month you move in.