The 15/50 Retirement Rule: A Complete Guide to How Much to Save

The 15% Savings Target

Many financial planners suggest saving about 15% of your gross income for retirement, starting in your 20s or 30s. That includes any employer match on a 401(k). If you start later, the percentage needs to be higher to catch up. Starting at 40 instead of 30? You may need to save 25% or more to reach the same goal.

The 50% Income Replacement Goal

A common target is to replace 50% to 80% of your pre-retirement income in retirement. You won't need 100% because you'll stop saving for retirement, may pay less in taxes, and lose work-related expenses like commuting and professional clothing. For many people, 50% to 60% is a reasonable planning assumption.

Where the Money Goes Before vs. After Retirement

• Retirement contributions (15%): Gone
• Payroll taxes (7.65%): Gone
• Commuting and work expenses (3-5%): Gone
• Mortgage (often): Paid off by retirement
• Result: You may only need 50-60% of pre-retirement income to maintain the same lifestyle

The 4% Withdrawal Rule

The 4% rule is a widely-cited guideline from the Trinity Study: if you withdraw 4% of your retirement savings in year one and adjust for inflation each year after, your money should last at least 30 years with a high probability of success. For a $1 million nest egg, that's $40,000/year.

Compound Growth Does the Heavy Lifting

You don't need to save the entire nest egg out of pocket. A large share of a typical retirement balance comes from investment growth, not contributions. For someone saving $500/month for 35 years at 7%, total contributions are $210,000 — but the final balance is about $830,000. That's $620,000 from compound growth alone.

Future Value = P × [((1 + r)^n − 1) / r]

P = monthly contribution
r = monthly return (annual ÷ 12)
n = number of months

The Impact of Starting Age

The difference between starting at 25 and 35 is staggering. Saving $500/month at 7%:

• Start at 25 (40 years): ~$1,312,000
• Start at 35 (30 years): ~$610,000
• Start at 45 (20 years): ~$260,000
• Each decade of delay roughly halves your final balance.

Social Security: Don't Count on It Alone

Social Security is designed to replace about 40% of pre-retirement income for average earners, less for higher earners. For someone making $100,000, Social Security might provide $25,000-$30,000/year. That's a helpful foundation, but you'll need significant additional savings to maintain your lifestyle.

Catch-Up Contributions

If you're behind, don't panic. People aged 50 and older can make extra 'catch-up' contributions to 401(k) plans ($7,500 above the standard limit) and IRAs ($1,000 extra). Combining catch-up contributions with a higher savings rate can close a gap faster than you'd expect.

Healthcare: The Wild Card

Fidelity estimates that a 65-year-old couple retiring in 2025 will need about $315,000 saved just for healthcare expenses in retirement — and that doesn't include long-term care. Medicare covers a lot but not everything. Factor healthcare into your retirement number separately from living expenses.

Consistency Beats Timing

The most reliable retirement strategy is boring: save automatically every month, keep costs low, and stay invested through market ups and downs. Time in the market matters more than timing the market.