Debt Benchmarks by Age: How Much Is Too Much, and What to Do About It
I spent most of my early 20s thinking about money in terms of savings. Debt was the thing I was supposed to get rid of as fast as possible. Then I started actually running the math and realized the picture is much more nuanced. Some debt at some ages is fine, or even smart. Other debt at other ages is genuinely dangerous to your financial future. (See also: Good Debt vs. Bad Debt on the path to FIRE.)
Here’s a framework for thinking about debt by life stage — not just how much you have, but what kind, and whether it’s moving in the right direction. Debt is only half the scoreboard — pair it with the honest net worth benchmarks by age.
The Debt Benchmark Framework
The most commonly cited debt benchmark is the debt-to-income ratio (DTI): your total monthly debt payments divided by your gross monthly income. Lenders use it. Financial planners reference it. Here’s how to interpret it:
- Below 20%: Excellent. Significant flexibility, low stress, strong FIRE potential.
- 20–28%: Good. Standard for most stable situations.
- 28–36%: Manageable. Watch for creep. Little margin for emergencies.
- 36–43%: Warning zone. Common among stretched homebuyers or recent graduates with heavy student loans.
- Above 43%: Lenders typically won’t approve new debt here. You shouldn’t either.
By Age: What the Debt Picture Should Look Like
| Age | Typical Debt Mix | FIRE-Aligned Target DTI | Red Flags |
|---|---|---|---|
| 22–27 | Student loans, maybe car | Under 25% DTI | Credit card debt growing; private student loans at high rates |
| 28–34 | Student loans, car, possibly mortgage | Under 30% DTI | DTI above 40%; debt total not declining |
| 35–42 | Mortgage, possibly remaining student/car debt | Under 25% DTI; non-mortgage debt eliminated or near it | Consumer debt growing; debt-to-income stable but not improving |
| 43–50 | Mortgage only (ideally) | Under 20% DTI; mortgage is the only debt | Any high-interest consumer debt; car loans for luxury vehicles |
| 50+ | Low or no mortgage; no other debt | Under 15% or mortgage-free | Debt growing in late career; borrowing to fund lifestyle |
Student Loans: The Generational Variable
Student loan debt is unavoidable for a large portion of graduates in their 20s and 30s. The question isn’t whether you have it — it’s the rate and trajectory. Federal loans at 5–7% in a tax-advantaged paydown context are manageable. Private loans at 9–12% are a crisis that should be attacked aggressively before any other saving beyond an employer 401(k) match.
Income-Driven Repayment (IDR) plans can reduce monthly payments during low-income years, but often extend the repayment period and increase total interest paid. Run the total cost calculation, not just the monthly payment.
The Mortgage Question for FIRE Seekers
Should you pay off your mortgage early or invest the difference? At a 3–4% mortgage rate (pre-2022 mortgages), investing in index funds historically wins over a long horizon. At 6.5–7.5% (current rates), the math is much closer, and psychological value of being debt-free matters more.
For early retirees: a paid-off home reduces the monthly expenses that determine your FIRE number. A lower FIRE number means less required portfolio, which can pull forward your retirement date significantly. Running both scenarios is worth the 15 minutes.
The One Debt Rule That Never Changes
At every age, the same rule applies: high-interest consumer debt (credit cards, personal loans above 8%) should never coexist with long-term investing. Paying off a 22% APR credit card is a guaranteed 22% return. No index fund reliably beats that. Clear consumer debt first, then invest. Every time.