The 15% rule, explained
Fidelity, Vanguard and the Center for Retirement Research at Boston College all converge on roughly the same number: a worker who saves 15% of gross income from age 25 to 65, invested in a balanced stock-heavy portfolio, will hit a retirement balance that supports ~80% income replacement using a 4% withdrawal rate.
The 15% includes your employer's 401(k) match. If your match is 4%, you only need to contribute 11% from your own pay to hit the 15% target. Counting the match correctly is critical, it's the cheapest portion of the 15%.
How the rate scales with starting age
- Start at 22: 12–15% of gross is sufficient.
- Start at 30: 15–18% needed.
- Start at 35: 20–22% needed.
- Start at 40: 25–28% needed.
- Start at 45: 30–35% needed.
- Start at 50: 40%+ needed (catch-up contributions help here).
- Start at 55: ~50% if achievable; consider working longer to age 70.
Life stage bends the rate
20s with student loan debt above 7% APR: pay debt before maxing investments beyond the 401(k) match. The math favors the guaranteed return of debt payoff.
30s buying a house: temporarily reducing investing to 10% to fund a down payment is reasonable; restore 15% within 12 months of closing.
40s with kids in college: don't sacrifice retirement for kids' tuition, they can borrow for school; you can't borrow for retirement. Maintain 15%+.
50s in peak earning years: aim for 20–25% to make up for any earlier years of under-saving.
Where to put each percentage point
- Up to the full 401(k) match (typically first 3–6%), instant 50–100% return.
- Max your IRA next ($7,000–$8,000), about $583/month for the under-50 limit.
- Return to 401(k) and contribute up to the $23,500 cap if income allows.
- HSA if you have HSA-eligible health coverage ($4,400 self / $8,750 family).
- Beyond all the above, taxable brokerage, in low-cost index funds.
Concrete numbers for a few common salaries
- $50,000 salary @ 15% = $7,500/year = $625/month → fully fits in an IRA + small 401(k).
- $75,000 salary @ 15% = $11,250/year = $937/month → IRA maxed + 6% to 401(k) gets you there.
- $100,000 salary @ 15% = $15,000/year = $1,250/month → IRA + 401(k) match + ~6% additional 401(k).
- $150,000 salary @ 15% = $22,500/year = $1,875/month → max 401(k) almost entirely; IRA likely Backdoor Roth.
- $200,000+ salary @ 15% = $30,000/year = $2,500/month → max 401(k) + Backdoor Roth + HSA covers most.
What 'too little' looks like
Saving only up to the 401(k) match (often 6%) and stopping there means most workers retire with ~$300,000–$500,000, a nest egg that supports roughly $1,200–$2,000/month at the 4% rule. For most lifestyles, that's a meaningful drop in living standard, requiring either working longer or accepting a tighter retirement.
Median 401(k) balance for Americans aged 55–64 is approximately $87,000 (Federal Reserve SCF), far below the $750,000+ that the 15% rule from age 25 would have produced.
What if you can't hit 15% right now?
Start with whatever you can, even 3% from your pay plus the match. Increase by one percentage point every six months; most people don't notice the bump after one paycheck. Many 401(k) plans have an 'auto-escalation' feature that does this automatically.
Save raises and bonuses with a 50/50 rule: half toward lifestyle, half toward investing. After 5–7 years, that pattern alone gets most steady earners to or above 15%.
