How to use the how long will my money last calculator
- Enter your starting savings.
- Enter your monthly spending and any other monthly income such as a pension or Social Security. Only the difference is drawn from savings.
- Enter an expected annual growth rate and inflation, and whether spending and income rise with inflation.
- Optionally enter your age to see the age when savings would be used up.
How the calculation works
Each month, the calculator withdraws your spending minus your other income from the balance, then grows what remains at the monthly equivalent of your annual growth rate. Once a year, spending and (if selected) income increase by the inflation rate. The simulation continues until the balance reaches zero or 100 years have passed; the depletion point is reported to the month.
Unlike the retirement withdrawal calculator, which tests a plan over a fixed horizon, this tool answers one question: how long until the money runs out?
Formula
- S, I
- Monthly spending and other income
- W
- Net monthly withdrawal (S − I)
- r
- Monthly growth rate = (1 + annual)1/12 − 1
- n
- Months until savings run out
Worked examples
$500,000 savings, $4,000 spending, $1,500 income
The net withdrawal starts at $2,500 a month ($30,000 a year, a 6% initial withdrawal rate). With 5% growth and both spending and income rising 3% a year, the projection shows how long the balance lasts; the annual table shows each year’s withdrawals and growth.
No growth, no inflation
$120,000 with a net withdrawal of $1,000 a month lasts exactly 120 months, or 10 years.
Assumptions and limitations
- Assumes constant growth and inflation. Real investment returns are volatile, and poor returns early on can shorten how long savings last.
- Taxes, large one-off expenses, health care costs and changes in spending over retirement are not modelled unless included in your monthly spending.
- This is an illustration for planning conversations, not financial advice.
Frequently asked questions
How long will $500,000 last in retirement?
It depends mostly on how much you withdraw. At a net $2,000 a month with 5% growth and 3% inflation it can last several decades; at $4,000 a month it may last well under 20 years. Enter your own numbers above.
Should I include Social Security?
Yes. Enter it as other income. Only spending above your other income is taken from savings, which can extend how long they last considerably.
What growth rate should I use?
Use a conservative long-run estimate for your mix of investments after fees. Try several rates to see how sensitive the result is.