Loan Calculator — Monthly Payment & Total Cost
Enter your loan amount, annual interest rate, term and any upfront fee to instantly see the monthly payment, total interest, total repaid, and the approximate APR.
%
年
Fixed monthly instalment covering principal and interest
23,479.38
total paid本金
85.2%
利息
14.8%
- 1
Monthly interest rate
r = 6.5% ÷ 12 ÷ 100 = 0.005417 - 2
Number of payments
n = 5 × 12 = 60 - 3
Growth factor
(1 + 0.005417)ⁿ = 1.3828How much one unit of principal grows over the full term at the monthly rate. - 4
每月還款
20,000 × 0.005417 × 1.3828 ÷ (1.3828 − 1) = 391.32
此計算機如何運作？
Monthly payment = P × r × (1+r)ⁿ / ((1+r)ⁿ − 1), where r = annual rate / 12 / 100 and n = term in months. For a £20,000 loan at 6.5% over 5 years: ≈£391/month, ≈£3,460 total interest. Add an upfront fee to see the true APR. Shorter terms cost more per month but less in total interest.
公式
How this is calculated
A fixed-rate loan is repaid through equal monthly instalments. Each payment covers the interest accrued on the remaining balance that month, plus a portion of the principal — so the interest component shrinks and the principal component grows over time (an amortising loan). The monthly payment is calculated with the standard amortisation formula: M = P × r × (1+r)ⁿ / ((1+r)ⁿ − 1), where P is the principal, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the number of monthly payments. A 0% rate is handled separately as M = P ÷ n.
Total interest is simply M × n − P; the total amount repaid is M × n. Adding an upfront origination or establishment fee gives the total cost of credit. The Annual Percentage Rate (APR) is a standardised measure that folds in that fee: it is the effective annual rate at which the net loan amount (principal minus the upfront fee, because the fee is paid at closing but you only receive the net proceeds) grows to cover all scheduled payments. The calculator uses Newton-Raphson iteration to find the APR when a fee is entered; with no fee the APR equals the nominal rate.
This calculator uses a fixed-rate, fully amortising model with equal monthly payments. It does not model variable-rate loans, balloon payments, prepayments, payment holidays, or country-specific consumer-credit regulations. For a detailed month-by-month amortisation schedule, see the amortisation calculator.
常見問題
The interest rate (or nominal rate) is used to calculate the monthly payment from the principal. The APR (Annual Percentage Rate) includes the interest rate plus all compulsory fees expressed as a single effective annual rate — making it easier to compare loan offers. When there are no fees the two are equal; when there is an upfront fee the APR is higher than the nominal rate.
A shorter term raises the monthly payment (you are repaying the same principal faster) but dramatically reduces total interest because the loan is outstanding for less time. A 5-year loan at 6.5% pays roughly half the total interest of a 10-year loan for the same principal, even though the monthly payment is almost double.
Yes, for a simple fixed-rate mortgage. Enter the mortgage amount, the annual interest rate, and the term in years (typically 15 or 30). Add any origination points or mortgage broker fees as the upfront fee to see the APR. Note that mortgages may also involve property taxes, home insurance, and PMI, which are not included here.
也稱為
TG we-Calculate Editorial Team. (2026). Loan Calculator — Monthly Payment & Total Cost [Online calculator]. TG we-Calculate. https://we-calculate.com/zh-tw/calculator/loan-calculator
TG we-Calculate Editorial Team. "Loan Calculator — Monthly Payment & Total Cost." TG we-Calculate. 2026. https://we-calculate.com/zh-tw/calculator/loan-calculator.
TG we-Calculate Editorial Team, "Loan Calculator — Monthly Payment & Total Cost," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/zh-tw/calculator/loan-calculator
@misc{wecalculate_loan_calculator, title = {Loan Calculator — Monthly Payment & Total Cost}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/zh-tw/calculator/loan-calculator}}, year = {2026}, note = {TG we-Calculate} }
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