Debt-to-Income (DTI) Ratio Calculator
From gross monthly income and monthly debt payments, compute DTI and the allowable debt ceiling and borrowing headroom.
輸入資料
計算結果
重點速覽：DTI = monthly debt payments / gross monthly income x 100%. ≤36% ideal; 43% common mortgage ceiling; above is hard to approve. This tool also computes debt limit = income x allowed DTI% and headroom = limit - current debt. Example: 50k income, 15k debt → 30%; at 36% limit, ceiling 18k, headroom 3k. WARNING: HK uses DSR + stress test for mortgages (different thresholds). Education, not advice.
計算公式
債務入息比 (DTI) = 每月債務還款 ÷ 稅前月入 × 100%。
每月債務上限 = 稅前月入 × 允許 DTI%。
尚可增加的每月還款 = 每月債務上限 − 現有每月債務 (不為負)。
$$\text{DTI} = \dfrac{\text{MonthlyDebt}}{\text{GrossMonthlyIncome}} \times 100\%$$$$\text{MonthlyDebtLimit} = \text{GrossMonthlyIncome} \times \text{AllowedDTI}\%$$$$\text{AdditionalDebt} = \max(0,\ \text{MonthlyDebtLimit} - \text{MonthlyDebt})$$使用說明
- Enter your pre-tax monthly income.
- Enter total monthly debt payments.
- Set an allowed DTI% to see current DTI and borrowing headroom.
稅前月入 HK$50,000 下，不同每月債務與允許 DTI% 的 DTI、每月債務上限與尚可增加還款對照表
| 每月債務還款 | 允許 DTI 上限 | 計算所得 DTI | 每月債務上限 | 尚可增加還款 |
|---|---|---|---|---|
| HK$10,000 | 36% | 20% | HK$18,000 | HK$8,000 |
| HK$15,000 | 36% | 30% | HK$18,000 | HK$3,000 |
| HK$18,000 | 36% | 36% | HK$18,000 | HK$0 |
| HK$21,500 | 43% | 43% | HK$21,500 | HK$0 |
| HK$25,000 | 50% | 50% | HK$25,000 | HK$0 |
以稅前月入 HK$50,000、DTI = 每月債務 ÷ 稅前月入 × 100% 及每月債務上限 = 月入 × 允許 DTI% 實算，數字四捨五入至整數，僅供參考。可見在 36% 上限下，每月債務達 HK$18,000 便用盡借貸空間;香港銀行按揭審批另採「供款與入息比率 (DSR)」及加息壓力測試，門檻與計法與此略有不同，實際可借金額以銀行審批為準。
理財情境案例
月入 HK$50,000、卡數月供 HK$15,000：DTI 30%，仍有 HK$3,000 空間
陳先生稅前月入 HK$50,000，現有每月債務還款合共 HK$15,000 (按揭、私人貸款與信用卡最低還款)。DTI = 15,000 ÷ 50,000 × 100% = 30%，屬 36% 理想線之內。
以 36% 為上限，其每月債務上限為 50,000 × 36% = HK$18,000，尚可增加約 HK$3,000 的每月還款。這代表若他再申請一筆月供不超過 HK$3,000 的貸款，DTI 仍可維持在 36% 的健康水平之內;但若新增月供超過此數，償債壓力便會偏高。
同樣月入、債務升至 HK$21,500：DTI 43% 已達按揭常見上限
若陳先生每月債務增至 HK$21,500，DTI = 21,500 ÷ 50,000 × 100% = 43%，剛好觸及國際上常見的按揭上限。此時以 43% 計的每月債務上限亦為 HK$21,500，尚可增加還款為 HK$0。
換言之，債務再增加就會超出多數機構願意批出的範圍，較難再獲批新貸款或需支付更高利率。要重新騰出借貸空間，可考慮提高收入、償清部分債務，或透過債務合併降低每月供款，把 DTI 拉回 36% 或以下的理想區間。
常見問題
What DTI is healthy?
Generally ≤36% is ideal and ~43% is the common mortgage ceiling; above 43% is hard to approve or carries higher rates. Lower DTI = less repayment pressure and better loan terms.
What counts as monthly debt?
Mortgage/rent, personal and car loans, credit-card minimums and fixed instalments. Everyday living expenses (food, utilities, transport) are NOT included. When unsure, include conservatively.
What should I enter for allowed DTI?
Your own or the lender's ceiling. Use 36% for a conservative health check, or 43% for the common mortgage ceiling. The tool derives your debt limit and headroom accordingly.
How does DTI differ from HK mortgage DSR?
HKMA requires banks to use DSR plus a stress test for residential mortgages: self-use DSR cap ~50% (40% if other mortgages/guarantees), with an interest-rate stress test. DSR is similar in spirit to DTI but differs in coverage, income definition and stress assumptions. This tool is for self-assessment; actual borrowing is per the bank under HKMA rules.
What is the formula and data basis?
Standard: DTI = monthly debt / gross monthly income x 100%; debt limit = gross income x allowed DTI%; headroom = limit - current debt (floored at 0). Health thresholds (36%/43%) are common international rules of thumb; HK mortgage DSR caps (50%/40%) follow HKMA. For reference only.
相關工具
參考資料
內容審核：香港計算器財經團隊。DTI 採用標準『每月債務還款 ÷ 稅前月入 × 100%』公式;健康門檻參考國際常用經驗值，香港按揭供款與入息比率上限參考香港金融管理局 (HKMA) 監管措施，結果僅供參考，實際以相關機構公佈為準。