How Long Will My Retirement Savings Last?

The Short Answer

To estimate how long retirement savings may last, start with the annual amount the portfolio must provide, then model how the balance changes as returns, fees, and inflation accumulate. A useful first-year formula is:

First-year portfolio withdrawal = annual spending - annual recurring income

The Retirement Withdrawal Calculator then runs a monthly projection. It applies one month of modeled growth to the current balance and takes the required withdrawal at month-end. Spending increases once per year with inflation. Recurring income can remain fixed in nominal dollars or increase at the same inflation rate.

The output is an illustrative duration or depletion age based on the assumptions entered. It is not a probability that a real portfolio will survive.

Why Balance Divided by Annual Withdrawal Is Incomplete

Dividing a $750,000 balance by a $35,000 annual withdrawal produces about 21.4 years. That shortcut assumes:

• no investment return;
• no investment or advice fees;
• no inflation;
• no change in spending;
• no growth in pension or other income;
• perfectly even withdrawals.

It can still be a useful zero-growth reference, but it should not be confused with a retirement drawdown model. Positive returns may extend the projection. Inflation, fees, or a fixed pension that loses purchasing power may shorten it. Those effects compound rather than occurring once.

Nominal and Inflation-Adjusted Assumptions

Klyrify's calculator keeps the return and inflation inputs separate. The investment return is nominal: it is the assumed percentage change before inflation. The annual fee is subtracted from that gross return to approximate a net annual rate. That annual rate is converted to an effective monthly rate.

Inflation does not reduce the portfolio return directly. Instead, it raises the spending need once each modeled year. This separation makes the assumptions visible. If you prefer to think in real returns, a useful precise relationship is:

Real return = (1 + nominal return) / (1 + inflation) - 1

Do not enter a real return while also applying inflation to spending unless that double adjustment is intentional.

Recurring Income Must Be Entered Manually

Pension income, public retirement benefits, annuity income, or dependable net rental income can reduce the amount withdrawn from the portfolio. Enter the annual amount you want the model to treat as recurring income.

The calculator does not look up benefit estimates, test eligibility, calculate tax, or know when an income source begins. If income starts later than retirement, run separate phases or scenarios. A fixed nominal income stream stays unchanged while spending rises. An inflation-linked income stream rises at the same entered inflation rate as spending.

The related guide on retirement income and FIRE numbers explains why delayed income requires a bridge-period plan.

Worked Example Matching the Calculator

Assume:

• starting age: 65;
• retirement savings: $750,000;
• annual spending: $50,000;
• annual recurring income: $15,000;
• gross annual return: 4%;
• annual investment fee: 0.30%;
• annual inflation: 2.5%;
• recurring income stays nominally fixed.

The portfolio must provide $35,000 in year one, which is a 4.67% initial withdrawal rate. The modeled net annual return is 3.70%. Using the calculator's monthly growth-first, withdrawal-at-month-end convention, the portfolio is depleted during month 272, or about 22 years and 8 months, at approximately age 87 years and 8 months.

This is not the same as saying the portfolio has a known expiry date. It is the result of one smooth-rate scenario. Changing the return, fee, inflation, or income-indexing setting changes the projection.

How to Read Depletion Age and the 100-Year Cap

A depletion result identifies the first modeled month in which the required withdrawal uses the remaining balance. The displayed age is the starting age plus the modeled months divided by 12.

“Not depleted within 100 years” means the balance stayed above zero through the calculator's technical cap of 1,200 months. It does not mean the plan is guaranteed, permanent, or free from risk. The cap prevents an open-ended simulation and gives very long-lasting scenarios a consistent stopping point.

Sequence-of-Returns Uncertainty

Real markets do not deliver the same return every month. Losses early in retirement can be more damaging than the same losses later because withdrawals remove assets before a recovery. This is often called sequence-of-returns risk.

The calculator does not simulate random returns, historical market paths, asset allocation, or success probabilities. Its constant-return model is better used to compare assumptions than to claim certainty. Two portfolios with the same long-run average return can have different real outcomes when the return sequence differs.

Using Low, Base, and High Scenarios Responsibly

Run at least three scenarios:

1. A lower-return or higher-inflation case to see where the plan becomes strained.
2. A base case using internally consistent assumptions you can explain.
3. A higher-return or lower-spending case to understand potential upside without treating it as promised.

Change one major assumption at a time when you want to see sensitivity. Then combine adverse assumptions for a stress case. Avoid labeling a high-return case “expected” merely because it produces a comfortable result.

How This Differs From Other Retirement Tools

The 4% Rule Calculator calculates a first-year withdrawal and future inflation-adjusted withdrawal amounts. It does not simulate portfolio depletion.

The FIRE Number Calculator estimates a target portfolio from expenses and a withdrawal rate. The FIRE Timeline Calculator estimates how long accumulation may take before retirement. The Inflation Calculator isolates purchasing-power change. The retirement withdrawal calculator begins after accumulation and models a monthly drawdown under steady assumptions.

Common Mistakes and Limitations

• Subtracting inflation from return and also inflating spending without understanding the double adjustment.
• Treating a pension as available from day one when it starts later.
• Ignoring portfolio-level fees or entering the same fee twice.
• Using total lifestyle spending in one scenario and essential spending in another without noting the difference.
• Reading a constant-return result as a market forecast.
• Forgetting taxes, account withdrawal order, one-off expenses, healthcare changes, or changes in housing.

The model also excludes asset allocation, tax rules, contribution after retirement, minimum-distribution rules, benefit eligibility, and legal or pension rules in the United States, Canada, Australia, or elsewhere.

Frequently Asked Questions

Is a lower initial withdrawal rate always safe? No single rate guarantees a result. A lower withdrawal reduces the first-year demand on the portfolio, but actual sustainability still depends on the horizon, return sequence, fees, inflation, taxes, and spending changes.

Should I enter pension income before or after tax? Use an amount consistent with the spending figure. If spending is an after-tax cash need, use the net recurring income expected to cover that need. Klyrify does not calculate the tax treatment.

What if recurring income covers all spending? The first-year portfolio withdrawal is zero. If income and spending rise at the same inflation rate, the modeled gap remains zero. If income stays fixed while spending rises, withdrawals may begin later.

Can this calculator test the 4% rule? It can model a spending gap that happens to equal 4% of the starting portfolio, but it is not a historical 4% rule backtest or a probability model. Use the separate 4% tool for the rule's withdrawal arithmetic.