Short answer
The Millionaire Next Door rule says expected net worth is age times pre-tax household income divided by 10. At 40 earning $100,000 that is $400,000; twice that ($800,000) is prodigious, half ($200,000) is under-accumulating.
1. The formula
Expected net worth = age × pre-tax annual household income ÷ 10. From the book by Thomas Stanley and William Danko: 2× expected is a "prodigious accumulator", 0.5× or less is an "under accumulator".
| Age | Income | Expected | 2× | 0.5× |
|---|---|---|---|---|
| 30 | $60,000 | $180,000 | $360,000 | $90,000 |
| 30 | $100,000 | $300,000 | $600,000 | $150,000 |
| 40 | $100,000 | $400,000 | $800,000 | $200,000 |
| 50 | $100,000 | $500,000 | $1,000,000 | $250,000 |
| 50 | $150,000 | $750,000 | $1,500,000 | $375,000 |
| 60 | $100,000 | $600,000 | $1,200,000 | $300,000 |
2. Limits of the rule
- It ignores inheritances and one-time windfalls.
- It works best mid-career; at young ages debt makes it harsh.
- It is a rough yardstick, not a Federal Reserve statistic.
Compare with real data in median net worth by age and use the Net Worth Calculator for your own number.
3. Frequently asked questions
What is the Millionaire Next Door formula?expand_more
Expected net worth = age times pre-tax household income divided by 10.
What counts as a prodigious accumulator?expand_more
Someone whose net worth is at least twice the expected figure.
Is the formula accurate for young people?expand_more
Less so. Student debt and early-career pay make it harsh under about 35.
Does it include inheritances?expand_more
No. It ignores windfalls, so an inheritance can distort the comparison.