還款進度時程表
詳列每年套用額外還款後的本金、利息支出與剩餘餘額變化。
| 年度 | 已付本金 | 已付利息 | 剩餘餘額 |
|---|---|---|---|
| 1 第 1 年 | $3,353 | $19,401 | $296,647 |
| 2 第 2 年 | $6,931 | $38,578 | $293,069 |
| 3 第 3 年 | $10,748 | $57,515 | $289,252 |
| 4 第 4 年 | $14,821 | $76,197 | $285,179 |
| 5 第 5 年 | $19,167 | $94,605 | $280,833 |
| 6 第 6 年 | $23,804 | $112,723 | $276,196 |
| 7 第 7 年 | $28,751 | $130,530 | $271,249 |
| 8 第 8 年 | $34,030 | $148,006 | $265,970 |
| 9 第 9 年 | $39,662 | $165,128 | $260,338 |
| 10 第 10 年 | $45,672 | $181,873 | $254,328 |
| 11 第 11 年 | $52,084 | $198,215 | $247,916 |
| 12 第 12 年 | $58,925 | $214,129 | $241,075 |
| 13 第 13 年 | $66,224 | $229,584 | $233,776 |
| 14 第 14 年 | $74,013 | $244,550 | $225,987 |
| 15 第 15 年 | $82,323 | $258,994 | $217,677 |
| 16 第 16 年 | $91,189 | $272,882 | $208,811 |
| 17 第 17 年 | $100,649 | $286,176 | $199,351 |
| 18 第 18 年 | $110,743 | $298,837 | $189,257 |
| 19 第 19 年 | $121,513 | $310,822 | $178,487 |
| 20 第 20 年 | $133,004 | $322,085 | $166,996 |
| 21 第 21 年 | $145,265 | $332,579 | $154,735 |
| 22 第 22 年 | $158,347 | $342,251 | $141,653 |
| 23 第 23 年 | $172,305 | $351,048 | $127,695 |
| 24 第 24 年 | $187,197 | $358,909 | $112,803 |
| 25 第 25 年 | $203,088 | $365,774 | $96,912 |
| 26 第 26 年 | $220,042 | $371,574 | $79,958 |
| 27 第 27 年 | $238,132 | $376,238 | $61,868 |
| 28 第 28 年 | $257,433 | $379,692 | $42,567 |
| 29 第 29 年 | $278,027 | $381,852 | $21,973 |
| 30 第 30 年 | $300,000 | $382,633 | $0 |
房貸怎麼算？ (本息平均攤還)
這是最常見的還款方式。在整個貸款期間，每個月的還款金額（本金+利息）是固定的。 * 優點: 每月繳款金額固定，方便理財規劃。 * 缺點: 前期繳的利息比例很高，償還本金的速度較慢。📊 30年 vs 40年房貸
近年來 40 年房貸越來越普遍，它的特點是： 1. 月付金降低: 比 30 年期減少約 20% 的月付壓力。 2. 總利息暴增: 雖然每月輕鬆，但總利息支出會比 30 年期多出非常多。買房能力評估 (333法則)
建議每個月的房貸支出不要超過家庭總收入的 33% (三分之一)，否則會嚴重擠壓生活品質與退休規劃存款。常見問題
Q: 寬限期是什麼？ A: 寬限期內 (通常 1-3 年) 「只繳利息，不還本金」。雖然這幾年很輕鬆，但寬限期結束後，本金會壓縮在剩下的年份償還，導致月付金暴增。此計算機暫以無寬限期計算。常見問題 (FAQ)
Q: How is a mortgage monthly payment calculated?
A: Monthly payment = Loan Amount × [r(1+r)^n] / [(1+r)^n − 1], where r = monthly rate (annual rate ÷ 12) and n = number of payments. For a $300,000 loan at 7% for 30 years: r = 0.07/12 = 0.005833, n = 360, monthly P&I = $1,996. This only covers principal and interest—add property tax, homeowners insurance, and PMI (if applicable) for your full monthly housing cost.
Q: What is the difference between a 15-year and 30-year mortgage?
A: A 15-year mortgage has higher monthly payments (roughly 30–40% more) but you pay far less total interest—often $200,000–$300,000 less on a $300,000 loan. 30-year mortgages offer lower monthly payments and more cash flow flexibility but dramatically higher total interest cost. 15-year loans also typically carry lower interest rates (0.5–0.75% less) from lenders. The right choice depends on your income stability and whether the monthly savings from a 30-year loan would be invested consistently.
Q: Does my monthly mortgage payment cover taxes and insurance?
A: Standard mortgage calculations show only Principal & Interest (P&I). However, most lenders require an escrow account that collects property taxes and homeowners insurance alongside P&I. These are added to your monthly payment to form the full PITI amount. Property taxes vary significantly by state (from under 0.5% to over 2% of home value annually). Always calculate your full PITI when budgeting for homeownership.
Q: How much of my early mortgage payments go to interest?
A: On a 30-year $300,000 mortgage at 7%, roughly 87% of your first payment goes to interest and only 13% reduces your principal. This gradually shifts over time—by year 15, it's roughly 70% interest / 30% principal, and by year 25, the split has reversed. This front-loading of interest is why extra principal payments made in the early years have such disproportionately large impact on total interest paid.
情境範例
幫我算出了 30 年和 40 年房貸的利息差距，雖然 40 年月付金低，但總利息真的太恐怖了。
介面很乾淨，沒有廣告，算起來很快，推薦給最近要買房的朋友。
333 法則的說明很有幫助，讓我重新評估了我的買房預算。
Official Sources & Authority References
重要免責聲明
本計算機提供之結果僅供參考，不構成稅務、法律或財務建議。稅法每年調整，請於申報前到 IRS.gov 核實數據，或談詢具資格的稅務專業人員。
