Retirement Drawdown Calculator

Will your money last? Enter your portfolio, planned withdrawals, and any pension or other income to see exactly how long your retirement savings hold out.

Starting Portfolio ($)

Everything you'll have invested when you retire. This is your starting runway.

Retirement Age

When you stop working and start drawing down. This is your day one.

Monthly Withdrawal ($)

What you plan to spend each month. It grows with inflation automatically.

Expected Annual Return (%)

Long-run stock returns run ~7–10%, entered as a nominal rate. Inflation is handled separately below.

Inflation Rate (%)

How fast prices climb. The US long-run average is ~2.5–3%.

Plan Through Age

How long you want your money to last. Default 95 covers a long retirement.

Income Sources (reduces your drawdown)

Lasts To Age

Years Funded

Total Withdrawn

Ending Balance

Balance at age --

Drawdown Timeline

Year-by-Year Projection

Year	Age	Withdrawal	Income	Net Drawdown Net	Balance	Status

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How We Calculate This

The drawdown model

Each month, the inflation-adjusted withdrawal is deducted from the portfolio at the start of the month, any pension or other income offsets the drawdown (surplus reinvested), and returns compound on the remaining balance:

Balance_next = (Balance − Withdrawal + Income) × (1 + Monthly Return)

Inflation-adjusted withdrawals

The year-1 withdrawal equals your entered monthly amount, and each subsequent month it grows at the monthly inflation rate. This matches the classic "4% rule" approach, where the initial withdrawal is a fixed real amount that grows with inflation. Withdrawal for month m:

Withdrawal_m = Monthly Withdrawal × (1 + Inflation/12)^m−1

Fixed nominal income

All income sources are modeled as fixed nominal amounts (not adjusted for inflation). In reality, some income sources (like Social Security) have cost-of-living adjustments, so this is a conservative simplification.

Surplus reinvestment

When income exceeds the withdrawal for a given month, the surplus is added back to the portfolio. It's not wasted. Strong income sources can actually grow your nest egg during the years they overlap with lower withdrawals.

Simulation horizon

The engine runs month-by-month through age 120 to detect whether the portfolio truly depletes. The table and chart show through your plan-through age, and the "Lasts To Age" result tells you the actual depletion point (up to 120).

Retirement Drawdown Calculator Formula

Each month, the inflation-adjusted withdrawal is deducted from the portfolio, any income offsets the drawdown, and returns compound on the remaining balance:

Balance_next = (Balance - Withdrawal + Income) x (1 + Monthly Return)

where Withdrawal grows with monthly inflation, Income is fixed nominal pension and other income, and Monthly Return is the annual expected return divided by 12.

How to Use This Calculator

Enter your Starting Portfolio, the total you'll have invested at retirement.
Enter your Retirement Age and Monthly Withdrawal, the amount you plan to spend each month (adjusted for inflation automatically).
Enter your Expected Annual Return and Inflation Rate to model investment growth and rising costs.
Set your Plan Through Age (default 95) to choose how long you want the money to last.
Optionally add Income Sources like pension, Social Security, or rental income, with their start ages. Add as many as you need.
Click Calculate to see whether your portfolio lasts and a year-by-year projection.

Frequently Asked Questions

What is a retirement drawdown?

A retirement drawdown (or decumulation) is the process of spending down your investment portfolio during retirement. Instead of adding money, you withdraw a set amount each month, adjusted for inflation, while the remaining balance continues to earn returns. The key question is whether your portfolio outlasts you.

What is the 4% rule?

The 4% rule is a guideline from the Trinity Study suggesting you can withdraw 4% of your portfolio in the first year of retirement, then adjust for inflation each year, with a high probability the money lasts 30+ years. This calculator lets you model any withdrawal rate and see the exact year your money runs out (or doesn't).

How does inflation affect my withdrawals?

Your monthly withdrawal grows with inflation each year so your purchasing power stays constant. If you start withdrawing $4,000/month with 2.5% inflation, by year 10 you're withdrawing about $5,120/month in nominal dollars. The calculator models this automatically.

What happens if my pension or other income exceeds my withdrawal?

Any surplus is reinvested. It reduces your net drawdown to zero, and the excess grows your portfolio. Strong income sources can actually grow your nest egg during the years they overlap with relatively low withdrawals.

How do I model Social Security?

Add an income source named "Social Security," enter your expected monthly benefit, and set the start age to your planned claiming age (e.g., 67). The calculator treats it as fixed nominal income. That's a simplification: actual Social Security has cost-of-living adjustments, so your real results may be slightly better.

What does 'plan through age' mean?

It's the age you want your money to last to. The default is 95, which provides a comfortable margin for longevity. The ending balance shows what's left at that age. The simulation actually runs to age 120 internally so the "Lasts To Age" result can show the true depletion point even beyond your plan horizon.

I came from the FIRE calculator. What should I change?

The FIRE calculator pre-fills your FI Number as the starting portfolio, your FI age as the retirement age, and your monthly spending as the withdrawal. You may want to adjust the expected return (retirement portfolios are often more conservative than accumulation portfolios) and add income sources like pension or Social Security. You can also explore longer horizons or compare your FIRE number against different drawdown scenarios.

Does this account for taxes or required minimum distributions?

This version models a single portfolio with one return rate. It does not model taxes, RMDs, Roth conversions, or separate account types. For tax-advantaged withdrawal sequencing, consult a financial advisor alongside this tool.