How to Use the Retirement Calculator
To estimate how much you need to retire, you need four things: how much you spend in a year, how many years until you retire, what you have saved already, and how much you add each month. Put those into the retirement calculator and it projects your balance at retirement and tells you whether your current pace gets you there. This guide walks through each input and how to read what comes back.
What you need before you start
The calculator asks for plain numbers about your situation, not financial jargon. Have a rough figure for each of these:
- Annual spending in retirement. What you expect a year to cost once you stop working. Many people land near their current spending, minus the mortgage if it is paid off and minus what they currently save.
- Years until retirement. Your target retirement age minus your age today.
- Current savings. The total in your retirement and investment accounts right now.
- Monthly contribution. What you add each month, including any employer match.
How to read the results
The calculator projects your balance forward to your retirement age and compares it against your target. Two things are worth understanding before you read too much into the number.
Future dollars vs today's dollars
The projection defaults to future dollars, the actual amount you would see in the account. That figure looks large because decades of growth and inflation are baked in. Switch the toggle to today's dollars to deflate it back to current purchasing power, which answers the more useful question: what would that balance buy if I had it now?
The target line
The target is your annual spending times 25, the amount that supports a 4% withdrawal rate. Clearing it is reassuring but not a guarantee. Falling short is a prompt to test changes, not a verdict.
The assumptions behind the numbers
Every projection rests on assumptions, and the calculator keeps them visible in the "Adjust assumptions" section rather than hiding them.
| Assumption | Default | Why it matters |
|---|---|---|
| Return | 10% nominal | Near the long-run S&P 500 average before inflation. Lower it to be conservative. |
| Inflation | 3% | Drives the gap between future and today's dollars. |
| Compounding | Monthly | Matches how contributions actually go in. |
The single most useful thing you can do is lower the return to something like 6 or 7% and see how far the result moves. If the plan only works at 10%, it is more fragile than it looks.
Try a few scenarios
The calculator is most useful when you change one thing at a time. Add $100 to the monthly contribution. Push retirement out two years. Drop the return by three points. Watching which lever moves the result most tells you where your own plan is sensitive, which is worth far more than any single projection.
Frequently asked questions
How much money do I need to retire?
A common rule of thumb is 25 times your annual spending, which corresponds to a 4% withdrawal rate. If you expect to spend $40,000 a year in retirement, that points to roughly $1 million. The calculator lets you replace the rule of thumb with your own numbers.
What rate of return should I assume?
The calculator defaults to a 10% nominal return, near the long-run historical average of the S&P 500 before inflation. You can lower it for a more conservative estimate. Returns are never guaranteed, so it is worth checking how the result changes when you do.
Does the calculator account for inflation?
Yes. Results default to future dollars, but you can switch to today's dollars to see what the projected balance would buy in current terms. The default inflation assumption is 3% and is adjustable.