Retirement savings gap calculator

Retirement savings gap — the honest math

Retirement planning rests on one simple equation: will your savings, plus future contributions, plus market growth, produce enough income in retirement to replace your working-life income? This calculator projects your nest egg at retirement age and compares it against the target nest egg needed to produce your desired retirement spending.

The nest egg target

The most common rule is the 4% rule, which says you need 25 times your annual retirement spendingsaved. $80k/year spending → $2M target. But the 4% rule assumes a specific mix (60/40 stocks/bonds), a specific timeframe (30 years), and specific historical return assumptions that may not repeat.

More recent research suggests a safer withdrawal rate of 3.3–3.75% (30× spending) for new retirees given current valuations and lower expected returns. If you're planning to retire early (before 60) and want 40+ years of spending, plan for 3% (33×).

How savings grow

Your retirement savings at age R = (current savings × (1 + r)^years) + annuity value of future contributions. Both components are sensitive to:

• Rate of return — historically U.S. stocks averaged ~10% nominal, but forward-looking projections are often 6–8%. Diversified portfolios (60/40) project 5–6.5%.
• Time horizon — the single biggest lever. Starting at 25 vs 35 dramatically changes the endpoint because of compounding.
• Contribution rate — for someone mid- career with limited time, contribution rate matters more than market timing. Adding $500/month for 20 years at 7% adds $260k.

Inflation — the silent scaler

"$80,000/year in retirement" in today's dollars is NOT $80,000 when you retire — it's the inflation-adjusted equivalent. At 3% inflation over 27 years, $80k today is $178k at retirement. Your nest-egg target must scale with this: 25 × $178k = $4.45M, not $2M.

The good news: investment returns nominally include inflation. A 7% nominal return is about 4% real. Both sides of the equation should be inflation-consistent — this calculator scales the target up with inflation while projecting the nest egg at nominal returns.

Social Security and pensions

This calculator defaults to a pure "portfolio only" model. In reality, most retirees have:

• Social Security: $1,500–$3,500/month for a 30-year worker at full retirement age. Add spouse's benefit. Typical replacement: 30–40% of pre-retirement income.
• Pension: still common for teachers, police, federal employees, and some union workers. Defined-benefit pensions can cover 40–70% of pre- retirement income depending on tenure.
• Part-time income: many "retired" people keep earning $10k–$30k/year from consulting, teaching, or side work. This can cut the nest-egg need significantly.

If you include Social Security in your income plan, subtract it from the "desired income" field before computing the gap. A $80k desired income with $30k/yr Social Security means you need $50k/yr from investments — a $1.25M nest egg at 4% withdrawal.

How to close a gap

If the calculator shows a gap, there are four levers:

1. Contribute more — the most direct lever. An extra $500/mo for 25 years at 7% adds $400k.
2. Retire later — every extra year of work does three things: one more year of contributions, one more year of growth, one less year of withdrawals. Adding 3 years often closes a 20% gap.
3. Spend less in retirement — either permanently or by relocating to a lower-cost area. $10k/yr of spending reduction cuts the nest-egg need by $250k at 4% withdrawal.
4. Take more investment risk — a higher-equity portfolio has higher expected return but also higher variance. Not appropriate for most near-retirees, but an under-saved 40-year-old may be too conservative and leaving growth on the table.

The 50/30/20 rule check

A simple check: if you're saving 20%+ of gross income (including employer match) and started by age 30, you're almost certainly on track for a traditional 65-retirement with 80% replacement. If you're saving 10% and started at 40, you're likely short. This calculator lets you verify with your specific numbers rather than relying on the rule.