Debt-to-Income Ratio Formula Explained, With Examples
Every debt-to-income ratio result comes from one formula. Once you understand what goes into it, you can sanity-check any figure you are given, whether by an employer, a bank, a teacher or another website.
The formula
DTI = monthly debts ÷ monthly income × 100.
What each input means
- Monthly debt payments (S$): the value you enter in the calculator.
- Gross monthly income (S$): the value you enter in the calculator.
Example
For example, with these inputs:
- Monthly debt payments (S$): 2,200
- Gross monthly income (S$): 7,000
the calculator returns:
- Debt-to-income ratio: 31.43%
How the result changes
The table keeps the other inputs at their example values and changes monthly debt payments (s$).
| Monthly debt payments (S$) | Debt-to-income ratio |
|---|---|
| 2,200 | 31.43% |
| 1,100 | 15.71% |
| 1,650 | 23.57% |
| 2,750 | 39.29% |
| 3,300 | 47.14% |
Why it matters
Interest rates, instalments and returns compound over years, so a small difference in rate or tenure turns into thousands of dollars. Working the numbers out yourself makes it easier to compare bank offers, avoid expensive debt and plan savings goals.
Calculators make it easy to compare scenarios side by side: a shorter tenure versus a lower instalment, a higher deposit versus more cash in hand, or paying down debt versus investing. Seeing the total cost, not just the monthly figure, usually makes the better choice obvious.
Compounding is the reason long-term saving works: returns earn further returns, so the growth curve steepens over time. The same maths works against you with debt, which is why credit card balances at around 27% a year grow quickly if only minimum payments are made.
Interest in Singapore is quoted in several ways. Mortgages and savings accounts use effective annual rates, while car loans and many personal loans are advertised at flat rates that look much lower than their true cost. Banks must disclose the effective interest rate, and comparing on that basis gives a fair picture.
Related calculations
- Inflation Calculator: Shows how inflation changes prices and purchasing power.
- Fixed Deposit Calculator: Calculates interest on a Singapore fixed deposit, which typically pays simple interest at maturity.
- Dividend Yield Calculator: Calculates dividend yield for SGX stocks and REITs.
- Break-Even Calculator: Finds how many units you must sell to cover costs.
Use the Debt-to-Income Ratio Calculator to plug in your own numbers.
Run your own numbers: Debt-to-Income Ratio Calculator