Calculator
Investment Savings and Distributions Calculator
Investment Savings and Distributions Calculator
Set to 0 for fixed payments, or ~2-3% to model inflation-adjusted withdrawals.
Portfolio Will Last
100+ yrs
Depletion Analysis
At $2,500 per month, your $500,000 portfolio survives at least 100 years and never depletes in our simulation. Your withdrawal is below the portfolio's $2,500 monthly growth allowance, so the principal largely sustains itself. This is a genuinely durable income stream.
*Assumes a constant monthly compounded return and an optional constant annual escalation of withdrawals. Real portfolios experience volatile year-to-year returns, and sequence-of-returns risk can shorten the actual duration. This is an estimate for planning, not investment advice.
How Long Will Your Investments Last Once You Start Withdrawing?
This calculator answers the fundamental decumulation question: if you start taking a fixed monthly distribution from your investment portfolio, how many years until the money is gone — or will it last forever? During your working years, money flows into investments; in retirement or during any spending phase, it flows out. The interaction between what the portfolio earns and what you withdraw determines whether your wealth grows, holds steady, or steadily declines to zero. The question is urgent for American households approaching retirement. Median balances among near-retirement households are often well under $300,000, and a $2,500 monthly distribution from that balance — without realistic returns — would exhaust the account in roughly ten years. Yet the same balance, growing at a 6% average return, can support meaningful withdrawals indefinitely, because the portfolio's monthly growth allowance replaces a portion of the spending. This tool simulates your portfolio month by month, shows total withdrawals versus the starting balance, and flags exactly when (or whether) depletion occurs.
Month-by-Month Depletion Simulation
Rather than a single closed-form estimate, this calculator advances the portfolio one month at a time. Each month it applies the monthly growth rate — annual return ÷ 12 — then subtracts that month's distribution: Balance = Balance × (1 + r/12) − Distribution. You can optionally raise the distribution each year by an escalation rate, modeling inflation-adjusted withdrawals. The loop continues until the balance hits zero or the 100-year cap is reached, giving both the months of survival and the cumulative dollars withdrawn. Three derived metrics round out the analysis. First, the monthly growth allowance — starting balance × annual return ÷ 12 — is the maximum constant distribution that, if not exceeded, leaves the principal untouched and allows the portfolio to last forever. Second, withdrawals expressed as a percentage of the starting balance, showing the total extraction. Third, a balance projection charted annually. When your distribution exceeds the growth allowance, capital is being consumed every month, and the gap between the two numbers determines how fast the clock is ticking.
Expert Insights
The Growth Allowance Is the Magic Number
At a 6% return, a $500,000 portfolio generates about $2,500 a month without touching principal. Withdraw at or below that level and the money never runs out; withdraw above it and you are on a countdown. Before choosing your monthly income figure, compute the growth allowance first and treat it as the upper ceiling for a perpetual stream.
Inflation Escalation Shortens Portfolio Life Faster Than You Think
A $2,500 monthly distribution raised 3% annually becomes $3,720 in year ten and $4,895 in year twenty. If returns do not keep pace, the later years drain the balance much faster than the early ones. If you must index withdrawals to inflation, plan on needing a starting balance roughly 20-30% higher than a nominal fixed-distribution plan would require.
Sequence Risk Is Invisible to This Model
A constant-average-return simulation assumes the same outcome regardless of when the returns happen, but real retirees face sequence risk: a major market decline in the first five years while withdrawing can permanently impair a portfolio, even if the long-run average return is identical. Hold one to two years of planned withdrawals in cash or short-term bonds so you never sell stocks in a drawdown.
Actionable Tips
- 1
Run Three Scenarios Before Setting Your Distribution
Test your portfolio with your target distribution at a pessimistic return (4%), base case (6%), and optimistic case (8%). If the pessimistic scenario depletes the account before your expected lifespan, reduce the monthly amount, plan to add income from other sources, or extend the withdrawal horizon.
- 2
Stress Fixed Expenses Against the Sustainable Monthly
List your non-negotiable monthly costs — housing, food, healthcare, insurance. Compare that total to your portfolio's growth allowance. If fixed expenses exceed the sustainable figure, your guaranteed income must cover the difference, or the principal will be consumed and the math becomes unforgiving.
- 3
Re-Run After Every Portfolio or Life Change
The inputs change more often than you think: a market rally raises the starting balance, a return assumption adjusts after a rebalance, and a spending decision raises the distribution. Keep this page bookmarked and recalculate whenever any input shifts materially — a thirty-second check keeps your plan honest.
Real-World Examples
Walt Avoided Running Dry at 82
Walt, 68, had $640,000 and was drawing $4,200 a month, assuming the '4% rule' would handle it. His annualized distribution of $50,400 equated to almost 8% of the portfolio — the calculator showed his money would run out in about 19 years, at age 87. He trimmed spending to $3,100 a month and moved two years of withdrawals into a CD ladder, extending the portfolio comfortably to his mid-90s.
The Riveras Built a Perpetual Stream
Elena and Marco Rivera, both retired at 60, had $1.4 million invested and a modest spending target of $3,000 a month, escalating 2.5% annually for inflation. At a 6.5% return assumption, the calculator projected the portfolio surviving 100+ years and growing substantially. Instead of taking more, they began gifting $20,000 a year to their children, converting excess returns into lifetime generosity.
Priya Timed Her Bridge Years
At 52, Priya needed $120,000 a year from her $380,000 savings until Social Security kicked in at 62 — a ten-year bridge. The calculator showed the account lasting just over 11 years at her spending level. That thin margin pushed her to delay retirement by two years, boost her savings rate, and take Social Security at 70 to maximize later income. She now has a five-year buffer at her planned spending.
Glossary of Terms
- Distribution
- A regular withdrawal of cash from an investment portfolio, typically monthly, to fund living expenses in retirement or a spending phase.
- Depletion Point
- The date at which a portfolio's balance reaches zero under a given withdrawal plan — the moment the money runs out.
- Sustainable Withdrawal
- A distribution level at or below the portfolio's expected growth, allowing the principal to be maintained indefinitely rather than consumed.
Frequently Asked Questions
Everything you need to know about this topic.
Ivy Sinclair-Wren
Financial Chaos Analyst
Ivy Sinclair-Wren is a Financial Chaos Analyst covering investing, AI, wealth psychology, and the emotional consequences of opening finance apps during market crashes. Based in Melbourne, she specializes in demystifying the US tax code and helping users navigate the intersection of spreadsheet logic and human irrationality.