Equal monthly installments: get your payment and total interest
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A loan is simple to describe but hard to compare: two offers can share the same monthly payment yet cost very different amounts overall. This calculator turns the three inputs that define a standard amortising loan — principal, annual rate and term — into the numbers that actually decide whether a deal is good: the fixed monthly instalment, the total you repay, and how much of that total is pure interest.
Enter the amount you borrow, the nominal annual interest rate, and the term in years or months. The tool returns the equated monthly instalment (EMI), the total repayment, and the share of that total which is interest. It models the common "equal instalment" structure used by personal loans, car finance and most fixed-rate mortgages, where the payment never changes but its composition drifts: early payments are mostly interest, later ones mostly principal.
Interest is charged on the outstanding balance, so the balance grows by a factor of (1 + r) each month while the fixed payment pushes it down. The formula solves for the constant payment that clears the loan exactly after n months.
You borrow $20,000 at 6% a year for 5 years. The monthly rate is 0.06 ÷ 12 = 0.005 and n = 60.
The payment is about $386.65 a month. Over 60 months you repay roughly $23,199, so total interest is about $3,199 — around 14% of everything you pay. Stretching the same loan to 7 years lowers the payment to roughly $292 but adds almost $1,350 of extra interest.
| Term | Monthly payment | Total interest |
|---|---|---|
| 3 years | ≈ $608 | ≈ $1,904 |
| 5 years | ≈ $387 | ≈ $3,199 |
| 7 years | ≈ $292 | ≈ $4,545 |
同样是"每月还多少"，不同贷款方案的实际成本可能相差很大。本工具把定义一笔等额本息贷款的三个参数——本金、年利率和期限——换算成真正影响决策的数字：固定的每月还款额、还款总额，以及其中有多少是在付利息。
输入借款金额、名义年利率，以及以年或月为单位的贷款期限，工具会给出等额月供（EMI）、还款总额和利息占比。它采用个人消费贷、车贷以及多数固定利率房贷通用的"等额本息"结构：每月还款额固定不变，但内部构成会变化——前期还款里大部分是利息，后期大头才是本金。
由于利息按剩余本金计收，贷款余额每月按 (1 + r) 增长，而固定还款在不断抵消它。公式求解的正是"恰好让余额在第 n 个月清零"的那个固定月供。
借款 20,000 元，年利率 6%，期限 5 年。月利率为 0.06 ÷ 12 = 0.005，n = 60。
每月约还款 386.65 元，60 个月共还约 23,199 元，其中利息约 3,199 元，占总还款额约 14%。若把同一笔贷款拉长到 7 年，月供会降到约 292 元，但总利息要多付近 1,350 元。
EMI stands for Equated Monthly Installment: a fixed payment every month that repays both interest and principal over the loan term.
The calculator uses the amortisation formula M = P × r × (1+r)^n ÷ ((1+r)^n − 1), where P is the principal, r the monthly rate and n the number of months.
Yes, a longer term lowers the monthly payment but increases the total interest you pay over the life of the loan.