Credit Card Monthly Payment Calculator
Set a target payoff period and work backwards to the required monthly payment, plus total paid and total interest.
輸入資料
計算結果
重點速覽：Given a target payoff period, derive the fixed monthly payment via the annuity formula: P = R x CCB / (1 - (1+R)^(-T)), R = APR/12, T = months; at zero rate P = CCB/T. Total paid = P x T; interest = total - balance. Example: 10,000 at 18%, 24 months → ≈HK$499/mo, total ≈11,982, interest ≈1,982. Shorter term = higher monthly but less interest. WARNING: fixed rate, no new spending; issuer terms vary. Education, not advice.
計算公式
月利率 R = 年利率% ÷ 100 ÷ 12。
每月供款 P = R × CCB ÷ (1 − (1 + R)^−T);CCB 為結欠, T 為還清月數。
零利率時 P = 結欠 ÷ 月數。
總還款額 = P × T;總利息 = 總還款額 − 結欠。
$$月利率：$R=\dfrac{APR\%}{12}$$$$$每月供款：$P=\dfrac{R\times CCB}{1-(1+R)^{-T}}$ (零利率時 $P=CCB/T$)$$$$總還款：$P\times T$；總利息：$P\times T - CCB$$$使用說明
- Enter the current balance.
- Enter the APR.
- Enter the target months to see the required monthly payment and interest.
結欠 HK$10,000、APR 18% 下不同還清月數的月供與總利息
| 還清月數 | 每月需還 (HK$) | 總還款額 (HK$) | 總利息 (HK$) |
|---|---|---|---|
| 12 個月 | 916.80 | 11,001.60 | 1,001.60 |
| 24 個月 | 499.24 | 11,981.78 | 1,981.78 |
| 36 個月 | 361.52 | 13,014.86 | 3,014.86 |
| 結欠 30,000 / APR 24% / 24 月 | 1,586.13 | 38,067.19 | 8,067.19 |
理財情境案例
案例一：設定 24 個月還清 HK$10,000 卡數
某人有 HK$10,000 信用卡結欠，年利率 (APR) 18%，希望在 24 個月內按固定金額還清，想知道每月要還多少。
月利率 = 18% ÷ 12 = 1.5%。每月供款 = 0.015 × 10,000 ÷ (1 −(1.015)^−24) ≈ HK$499.24；24 個月共還約 HK$11,981.78，當中利息約 HK$1,981.78。
解讀：只要每月固定還約 HK$499，兩年內就能清還這筆卡數，代價是約 HK$1,982 的利息。相比只還最低還款額 (會拖很久且利息更高),設定明確的還清期限並按此供款，能更快擺脫債務、節省利息。
案例二：想省利息就縮短還清期
同樣是 HK$10,000、APR 18% 的結欠，比較 12 個月與 36 個月兩種還清安排。
12 個月：月供約 HK$916.80，總利息約 HK$1,001.60。36 個月：月供約 HK$361.52，總利息約 HK$3,014.86。
解讀：把還清期由 36 個月縮短到 12 個月，每月供款雖然由約 HK$362 大增到約 HK$917，但總利息由約 HK$3,015 大減到約 HK$1,002——省下超過六成利息。這說明在能負擔的前提下，盡量提高月供、縮短還清期，是節省信用卡利息最有效的方法。本工具假設利率固定、期間不再新增消費,實際以發卡機構為準。
常見問題
How is this different from the credit card payoff calculator?
The payoff calculator answers 'known monthly payment → how long to clear'. This one reverses it: 'known target months → how much to pay monthly'. Both use the same annuity math; only the known and unknown swap. Pick based on whether you start from a fixed monthly budget or a fixed deadline.
How does shortening the term affect payment and interest?
Shorter term = higher monthly but less time for interest to accrue, so total interest falls; longer term = easier monthly but more interest. Adjust months to balance affordable payment against total cost.
Will my result match the issuer exactly?
This estimates with a fixed annual rate and equal instalments. Actual may differ with daily accrual, fees or different methods, and assumes no new spending. Use the statement as final.
Why does halving the term save more than half the interest?
Card interest accrues on the unpaid balance each period; the longer you owe, the longer principal sits and compounds, and the relationship is non-linear. In the example, extending 12→36 months (3x) balloons interest ~3x; halving the term lets principal drop faster so later periods charge interest on a smaller base — savings exceed intuition. That is why paying more/faster is urged. HK card rates (20%-36%) far exceed loans, so a short target saves a lot.
How does this differ from the payoff calculator, again?
They compute in opposite directions for opposite goals. The payoff calculator takes a fixed monthly payment and outputs months-to-clear plus total interest — for when your monthly capacity is fixed and you ask 'when am I free'. This calculator takes a target months-to-clear and outputs the required fixed monthly payment — for when you have a clear 'clear it in N years' goal and want to budget. Both rest on the same annuity math, just swapping known and unknown. Choose by whether you start from 'how much can I pay' or 'by when do I want it gone'.
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。