How to Use This Calculator
Enter your current age, when you want to retire, and how long you expect to live. Add your current savings, how much you're contributing each month, and what you think you'll spend in retirement. The calculator projects whether your money will last — and if it won't, it tells you exactly how much more you need to save each month to close the gap.
The most important number on the results page? "Savings Last Until Age." If that number is lower than your life expectancy, you have a shortfall to address. If it's higher, you're on track.
Here's what each field means:
Current Age is where you are today. The calculator uses this to determine how many saving years you have left.
Retirement Age is when you plan to stop working. The traditional target is 65-67, but you can model any age. Social Security's full retirement age is 67 for anyone born in 1960 or later [1].
Life Expectancy is how long you expect to live. This is uncomfortable to think about, but it matters — a lot. The average American who reaches age 65 will live to about 84 (men) or 87 (women) [2]. But "average" means half of people live longer. Setting this to 90 or 95 gives you a safety margin. Running out of money at 88 because you planned for 85 is a problem without a good solution.
Current Retirement Savings is the total you've accumulated across all retirement accounts — 401(k), IRA, Roth IRA, brokerage accounts, anything earmarked for retirement. Don't include your home equity unless you plan to sell and downsize.
Monthly Contributions is how much you're putting away each month toward retirement. This includes 401(k) contributions, IRA deposits, and any other regular savings.
Monthly Budget in Retirement is what you expect to spend each month after you stop working. A common rule of thumb is 70-80% of your pre-retirement income [3], but your actual number depends on your lifestyle. Will your mortgage be paid off? Will you travel more? Will healthcare costs increase? Think through the specifics.
Other Retirement Income covers money coming in from sources other than your savings — Social Security, a pension, rental income, part-time work, or annuity payments. This reduces how much your portfolio needs to provide each year.
Asset Allocations Before Retirement is your investment mix during your working years. A more aggressive allocation (heavier on stocks) aims for higher growth when you have decades to ride out market downturns.
Asset Allocations After Retirement is your investment mix once you start withdrawing. Most people shift toward more bonds and less stocks to reduce volatility, since you can't afford a 30% market drop when you're pulling money out to live on.
Expected Returns are the annual growth rates you expect for stocks, bonds, and cash. Historical long-term averages: stocks around 10%, bonds around 4-5%, cash around 2-3% [4]. These are before inflation.
The Two Big Questions in Retirement Planning
Every retirement plan boils down to two questions: Will I have enough? And will it last?
"Enough" means accumulating a portfolio large enough to cover your expenses for the rest of your life. "Last" means making sure you don't spend it down too fast.
This calculator answers both. It projects what you'll have at retirement (based on your current savings and future contributions), compares it to what you'll need (based on your spending plan and life expectancy), and tells you whether there's a gap.
The 80% Rule — And Why It's Only a Starting Point
Financial planners often say you'll need about 80% of your pre-retirement income in retirement [3]. The logic: some costs disappear (commuting, professional wardrobe, payroll taxes, retirement contributions), so your overall expenses drop.
If you earn $100,000, the 80% rule says you'd need $80,000 per year in retirement. At a 4% withdrawal rate, that requires a $2 million portfolio.
But this is a rough estimate. Your number could be higher or lower depending on:
Costs that typically go down: commuting expenses, work clothes, payroll taxes (no more Social Security or Medicare contributions on earned income), retirement savings contributions (you're done saving).
Costs that typically go up: healthcare (this is the big one — a 65-year-old couple can expect to spend $315,000+ on healthcare in retirement, even with Medicare [5]), travel, hobbies, home maintenance (if you're now home more often).
Costs that might disappear entirely: mortgage (if paid off by retirement), children's expenses (if they're financially independent).
The best approach is to build a bottom-up estimate. List your expected monthly expenses item by item rather than relying on a percentage rule.
Social Security: What You'll Actually Get
Most Americans qualify for Social Security benefits, and for many retirees, it's a significant income source. The average monthly benefit in 2025 is about $1,976, or roughly $23,700 per year [6].
The key decision is when to start collecting:
Age 62 — You can start early, but your benefit is permanently reduced by about 30% compared to waiting until full retirement age [1].
Age 67 — Full retirement age for most current workers. You receive 100% of your calculated benefit.
Age 70 — For every year you delay past 67, your benefit increases by 8%. By age 70, you'd receive 124% of your full benefit. After 70, there's no further increase [1].
The math is simple but the decision isn't. If you're in excellent health and expect to live past 80, delaying usually pays off. If you need the income now or have health concerns, starting earlier makes sense.
Enter your expected Social Security benefit in the "Other Retirement Income" field to see how it changes your overall picture.
How Much Should You Be Saving?
The general guideline is 15% of your gross income, including any employer match [7]. But that assumes you start in your mid-20s and maintain it consistently.
If you started late, you'll need to save more to catch up. Here's a rough framework:
Started saving at 25: 15% of income is typically sufficient for a retirement at 67.
Started saving at 35: You'll likely need 20-25% to reach the same goal.
Started saving at 45: You may need 30%+ or plan to work longer, downsize expenses, or both.
The calculator lets you test all of these scenarios. Plug in your actual numbers, see the gap, then adjust your monthly contributions until the projected savings last through your life expectancy.
What the Chart Shows You
The chart displays two lines across your lifetime:
"What You'll Have" (green) tracks your projected portfolio value. It rises during your working years as contributions and investment growth accumulate. After retirement, it curves downward as you make withdrawals.
"What You'll Need" (blue) shows the minimum portfolio required at each age to sustain your planned withdrawals through your life expectancy. This is your target — your green line needs to stay above it.
If the green line dips below the blue line, your savings run out before you planned. The gap between the two lines at retirement age tells you how over- or under-funded your plan is.
Common Retirement Planning Mistakes
Underestimating healthcare costs. This is the #1 planning blind spot. Medicare doesn't cover everything — dental, vision, hearing, long-term care, and supplemental insurance premiums add up fast. Budget more than you think you'll need.
Ignoring inflation. $7,000/month sounds comfortable today. In 20 years at 3% inflation, you'd need about $12,600/month to maintain the same lifestyle. The calculator accounts for this, but make sure your inflation assumption is realistic.
Planning for average life expectancy. If the average is 85, half of people live past 85. Plan for 90-95 to avoid the catastrophic scenario of outliving your money.
Not accounting for taxes. Traditional 401(k) and IRA withdrawals are taxed as ordinary income. If all your retirement savings are in tax-deferred accounts, you'll owe income tax on every dollar you withdraw. A mix of traditional and Roth accounts gives you more flexibility.
Assuming a fixed spending rate. Retirees often spend more in the first decade (travel, activities, projects) and less later as they slow down. But healthcare costs often surge in the final years. The overall trajectory isn't flat.
How to Use This Calculator Strategically
Close the gap. If your savings won't last, the calculator tells you exactly how much more you need per month. Even an extra $200/month can shift your outlook dramatically over 15-20 years.
Test your retirement age. Working just two extra years has an outsized impact — it adds contributions, adds investment growth, and reduces the number of years your portfolio needs to sustain. Try 65 vs. 67 vs. 70 and compare.
Model Social Security timing. Enter different amounts in "Other Retirement Income" to see how claiming at 62 vs. 67 vs. 70 affects your portfolio longevity.
Stress-test with lower returns. Run the calculator at 5% stock returns instead of 10%. If your plan still works under conservative assumptions, you're in strong shape.
Plan for the unexpected. Add $500-$1,000/month to your retirement budget as a buffer for healthcare surprises, home repairs, or helping family members. It's better to have too much than too little.
References
- Social Security Administration. (2025). Retirement Benefits.
- Social Security Administration. (2025). Actuarial Life Table.
- Fidelity Investments. (2025). How Much Do I Need to Retire?
- Damodaran, A. (2024). Historical Returns on Stocks, Bonds and Bills: 1928-2023. NYU Stern School of Business.
- Fidelity Investments. (2025). How to Plan for Rising Health Care Costs.
- Social Security Administration. (2025). Monthly Statistical Snapshot.
- Fidelity Investments. (2025). How Much Should I Save for Retirement?
This calculator is for educational purposes only and does not constitute financial advice. Actual investment returns vary, and past performance does not guarantee future results. Consider consulting a qualified financial advisor for personalized guidance.