Credit Card Payoff Calculator
From balance, APR and monthly payment, compute the months, total paid and total interest to clear the card.
輸入資料
計算結果
重點速覽：Paying a fixed amount each month, monthly interest = balance x APR/12; next balance = balance + interest - payment, repeated until cleared. Months, total paid and total interest are output. Example: 20,000 at 24%, pay 800/mo → ~29 months, total paid ~23,220, interest ~3,220. Compare with minimum payment that can stretch to decades. WARNING: if payment ≤ first-month interest, never clears (tool flags it). To cut cost: clear in full, or move to a lower-rate loan / 0% balance transfer. Simplified model. Education, not advice.
計算公式
月利率 = 年利率% ÷ 100 ÷ 12。
逐月模擬：每月結欠 = 上月結欠 × (1 + 月利率) − 每月還款額。
重複直至結欠 ≤ 0，累計月數為還清月數;累計扣除額為總還款額。
總利息 = 逐月計息之和 (即總還款額 − 原結欠)。
若每月還款 ≤ 首月利息，結欠不減反增，無法還清。
$$\text{月利率}\; r = \dfrac{\text{APR}\%}{12}$$$$\text{下月結欠} = \text{本月結欠} \times (1 + r) - \text{每月還款}$$$$\text{還清條件}:\; \text{每月還款} > r \times \text{結欠}\;(\text{否則結欠越滾越大})$$使用說明
- Enter the current balance.
- Enter the APR.
- Enter the fixed monthly payment to see months and total interest.
以信用卡結欠 30,000、年利率 (APR) 24% 為例，不同每月固定還款額下的還清月數與總利息 (HK$)。
| 每月還款 | 還清月數 | 總還款額 | 總利息 |
|---|---|---|---|
| 1,000 | 47 個月 | 46,273 | 16,273 |
| 1,500 | 26 個月 | 38,696 | 8,696 |
| 2,000 | 19 個月 | 36,023 | 6,023 |
| 3,000 | 12 個月 | 33,811 | 3,811 |
理財情境案例
案例一：只還最低額 vs 定額還 2,500
陳小姐信用卡結欠 50,000、年利率 (APR) 30%。若她每月只還約 1,000 (接近常見的最低還款額)，結果會如何？
首月利息 = 50,000 × 30% ÷ 12 = 1,250，已高於還款 1,000。由於每月還款低於利息，結欠不減反增，計算器顯示「無法還清」—— 這就是最低還款陷阱。
若改為每月定額還 2,500，則約 29 個月清還，總還款約 70,180、總利息約 20,180。同一筆卡數，「只還最低」永遠還不完，「定額多還」不足三年清袋 —— 差別是能否翻身。
案例二：把高息卡數轉為低息私人貸款
王先生卡數 30,000、APR 24%，本打算每月還 1,500，需約 26 個月，總利息約 8,696。他考慮改用年利率 12% 的私人貸款 (P Loan)、分 24 個月償還「結餘轉戶」。
私人貸款月供 = 30,000 × [0.01×(1.01)^24] ÷ [(1.01)^24 − 1] ≈ 1,412；24 個月總還約 33,893、總利息僅約 3,893。
同樣兩年多還清，轉為低息貸款後利息由約 8,696 降至約 3,893，慳逾 4,800。若卡數金額大且利率高，「轉為較低息貸款 / 結餘轉戶」往往是慳息的關鍵一步，但要留意手續費與轉戶後切勿再碌爆張卡。
常見問題
How is credit card interest calculated?
If you don't clear the balance in full within the grace period, the bank charges monthly interest = outstanding balance x APR / 12, compounding. Paying only the minimum covers mostly interest, so principal falls slowly.
How high is a Hong Kong credit card APR?
HK credit-card revolving APRs commonly exceed 30%; the HKMA example uses about 2.5% per month (~35% effective annual). Banks must disclose APR uniformly per the Code of Banking Practice.
What is the minimum payment trap?
Hong Kong minimum payment is typically 'all interest and fees + at least 1% of principal' (or ~HK$50, whichever higher). Paying only that avoids late fees but reduces principal extremely slowly — repayment can stretch over decades with total interest multiple times the principal.
How can I pay off faster and cheaper?
Pay more than the minimum each month (big interest savings); or move the balance to a lower-rate personal loan or 0% balance-transfer promo; best, clear in full to use the interest-free period. Avoid re-spending on the cleared card.
Why might the calculator say it can't be paid off?
When the monthly payment is ≤ the first month's interest, the balance grows instead of shrinking and interest accrues without limit. Raise the monthly payment above the interest to start reducing principal.
相關工具
參考資料
內容審核：香港計算器財經團隊。計算邏輯與公式參考香港金融管理局（HKMA）及投資者及理財教育委員會（IFEC）之個人理財計算指引，結果僅供參考，實際以相關機構公佈為準。