Two Sides of the Same Equation
Imagine standing on a seesaw. On one side, your monthly debt payments push down. On the other side, your monthly income pushes up. When income far outweighs debt, you're standing tall with plenty of room. When debt payments creep close to what you earn, the balance tips — and your financial breathing room shrinks.
Your Debt-to-Income ratio (DTI) measures that balance. It's one of the metrics lenders check before approving a mortgage or loan, and it carries 15% of your Wambai financial health score. But it can only work when you track both sides of the equation.
What Powers the DTI Metric
The formula is simple:
DTI = Total Monthly Debt Payments / Monthly Income
Two distinct data inputs:
Input 1: Your Credits (Debt Side)
Credits in Wambai represent your active debts — both traditional loans and revolving credit:
Traditional loans (fixed payments):
- Mortgage
- Auto loan
- Student loan
- Personal loan
For each loan, Wambai knows the monthly installment amount from the credit's payment schedule.
Revolving credit (variable payments):
- Credit cards
- Lines of credit
For revolving credit, the monthly payment is typically the minimum payment or whatever you regularly pay.
The total of all these monthly debt payments is the numerator in your DTI calculation.
Input 2: Your Recurring Income Rules (Income Side)
Your monthly income comes from the recurring income rules you've set up. Salary, freelance income, rental income, side business revenue — every source counts.
Wambai normalizes all income to a monthly figure, regardless of how often you're paid. Weekly, biweekly, monthly, quarterly — it all gets converted to a monthly total.
This income total is the denominator in your DTI calculation.
Why Both Sides Must Be Complete
The DTI ratio is meaningless if either side is wrong. And here's the critical thing: if you haven't set up income rules at all, the DTI metric returns no result. It literally can't calculate without a denominator.
Missing Income Data
Mateo has three credit cards and a car loan. He diligently set up all four credits in Wambai, showing $850 in total monthly debt payments. But he never set up his income rules. Result: the DTI metric shows nothing. He's tracking debts without context — $850 per month could be manageable or crushing depending on whether he earns $3,000 or $10,000.
Fix: Set up recurring income rules. Even just your primary salary is enough to activate this metric.
Missing Credit Data
Camila earns $6,000/month and set up her income rules. She added her mortgage ($1,400/month) but forgot about her car loan ($350/month) and two credit cards she carries small balances on ($120/month combined). Wambai calculates her DTI as 23% — but the real number is 31%. That pushes her from a "comfortable" range into a "needs attention" range.
Fix: Add all active credits to Wambai, including small balances. Every monthly payment counts.
Setting Up Credits in Wambai
Credits come in two flavors, and each requires slightly different data:
Traditional Loans
For a traditional loan (mortgage, car loan, student loan, personal loan), you need:
- Loan amount (original principal)
- Interest rate (annual percentage rate)
- Monthly payment amount
- Remaining balance
- Payment schedule (monthly installments with dates)
The monthly payment is what matters for DTI. A $200,000 mortgage at $1,400/month contributes $1,400 to your debt payments, regardless of the total loan size.
Revolving Credit (Credit Cards)
For credit cards and lines of credit, you need:
- Credit limit (maximum borrowing amount)
- Current balance (what you owe right now)
- Monthly payment (minimum or what you actually pay)
- Interest rate (APR)
Credit card data does double duty: the monthly payment feeds your DTI score, while the balance, limit, and interest rate also feed your Debt Efficiency score.
The DTI Thresholds That Matter
Your DTI score translates the ratio into a 0-100 scale:
| DTI Ratio | Score | What It Means |
|---|---|---|
| 10% or less | 100 | Excellent — minimal debt burden |
| 10-20% | 70-100 | Good — manageable with room to breathe |
| 20-36% | 30-70 | Getting tight — lenders start paying attention |
| 36-50% | 0-30 | Strained — most of your income goes to debt |
| 50%+ | 0 | Critical — more than half your income goes to debt |
The 36% threshold is particularly important. Most mortgage lenders won't approve borrowers with a DTI above 36-43%. If your DTI is approaching that range, it affects not just your score but your real-world borrowing capacity.
How DTI Connects to Other Metrics
Shared Data with Savings Rate
Your income rules are shared with the Savings Rate metric. The same income data serves as the basis for both calculations. This means setting up income rules unlocks both metrics simultaneously.
Shared Data with Debt Efficiency
Your credits are shared with the Debt Efficiency metric. DTI looks at the monthly payment amount; Debt Efficiency looks deeper at interest rates, utilization, and overdue payments. Same credit entries, different analysis.
Impact on Emergency Fund
When debt payments are high, less money flows to savings, which means your emergency fund builds slower. A high DTI indirectly pressures your Emergency Fund score too.
Practical Example: Renata's Full Picture
Renata earns $5,500/month and has the following debts:
| Credit | Monthly Payment |
|---|---|
| Mortgage | $1,400 |
| Car loan | $380 |
| Student loan | $280 |
| Credit card (regular use) | $150 |
Total monthly debt payments: $2,210
DTI: $2,210 / $5,500 = 40.2%
That's in the strained range. Renata's score on this metric would be low, reflecting real financial pressure. But now she knows — and she can make a plan. Maybe she accelerates the car loan payoff to free up $380/month, which would drop her DTI to 33% and move her into a more comfortable range.
Without tracking both sides, she'd never have this clarity.
Two Paths to Improvement
The math offers two levers:
Reduce Debt Payments (Numerator)
- Pay off a loan entirely (eliminates that monthly payment)
- Refinance at a lower rate (reduces the monthly payment)
- Pay down credit card balances (reduces minimum payments)
Increase Income (Denominator)
- Negotiate a raise
- Add a side income stream
- Grow an existing business
Both paths improve the ratio. The best approach depends on your situation — sometimes earning $500 more per month is easier than cutting $500 in debt payments, or vice versa.
The Bottom Line
Your DTI score needs two complete data sets: all your credits (with accurate monthly payments) and all your income sources (as recurring rules). When both sides are tracked, you get a clear picture of your financial breathing room — how much of every dollar you earn is already spoken for by debt.
Set up your credits. Set up your income rules. Let the ratio tell you where you stand.
For a deeper dive into DTI as a concept — what the ratio means, why lenders care, and strategies for improving it — read Debt-to-Income Ratio Explained.
