Quick answer
This calculator grows your current savings and a monthly contribution at a fixed annual return until your retirement age. It shows the balance in future dollars, the same balance adjusted for an inflation rate you choose, and how much of it you contributed yourself [1].
Key points
- Years of saving = retirement age − current age.
- The balance compounds monthly at one-twelfth of the annual return, with contributions added at the end of each month.
- The today's-dollars figure divides the future balance by (1 + inflation) raised to the number of years.
- Small changes in the return or inflation rate change the result a lot over decades.
- Taxes, fees, Social Security and changing returns are not included.
#What does this calculator estimate?
It answers one narrow question: if I keep saving the same amount and my money earns a steady return, roughly how much might I have when I retire, and what would that buy in today's prices? The inputs are Current age, Retirement age, Current savings, Monthly contribution, Annual return and Inflation.
You get four results: Estimated balance at age … (nominal) — the raw future-dollar figure at your retirement age; In today's dollars — the same balance adjusted for inflation; Total contributed — your current savings plus every monthly contribution; and Years of saving. The second number matters because, as the US Department of Labor puts it, inflation means "dollar for dollar your money will not buy as much next year as it does this year" [1].
#How does the calculation work?
Let r be the annual return and i the inflation rate, both as decimals, and C the monthly contribution.
- Years = retirement age − current age. Months = years × 12.
- Each month: new balance = old balance × (1 + r ÷ 12) + C, starting from current savings.
- Balance at retirement (nominal) = the balance after the final month.
- In today's dollars = nominal balance ÷ (1 + i)^years.
- Total contributed = current savings + C × 12 × years.
The inflation step uses a single steady rate. In the US, the Bureau of Labor Statistics tracks price changes with the Consumer Price Index, "a measure of the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services" [2]. Real inflation varies from year to year; the calculator smooths it into one number you choose.
Worked example
Worked example: saving from 30 to 65
Current age 30 · Retirement age 65 · Current savings $20,000 · Monthly contribution $500 · Annual return 6% · Inflation 2.5%. Calculated in Python with the steps above.
- Years of saving (65 − 30)
- 35
- Total contributed ($20,000 + $500 × 12 × 35)
- $230,000.00
- Balance at retirement (nominal)
- $874,826.18
- Inflation divisor (1.025^35)
- 2.3732
- In today's dollars ($874,826.18 ÷ 2.3732)
- $368,626.44
The future balance looks large, but at 2.5% yearly inflation it would buy about what $368,626 buys today.
Hypothetical inputs. Fixed return and inflation, before taxes and fees. Not a forecast or a savings target.
#How much do the assumptions matter?
Over 35 years, a couple of percentage points in the return assumption change the outcome dramatically. The table keeps every other input from the example the same.
| Annual return | Balance at retirement (nominal) | In today's dollars |
|---|---|---|
| 4% | $537,780.86 | $226,605.30 |
| 6% | $874,826.18 | $368,626.44 |
| 8% | $1,472,792.24 | $620,592.04 |
Balance in today's dollars by starting age (retire at 65)
#What this calculator leaves out
- Taxes. Traditional and Roth accounts are taxed differently, and withdrawals may be taxable. See Traditional vs Roth IRA.
- Fees. Fund expenses reduce growth every year; the fee impact calculator shows how much.
- Employer matches and raises. Contributions stay flat for the whole period.
- Social Security and pensions. Other income in retirement is not included.
- Uneven returns. Real markets go up and down, and a bad stretch just before retirement can matter more than the average.
#How can you use the result?
Compare the today's-dollars figure with the income you might need. The Department of Labor suggests a quick estimate of "at least 70 percent of your preretirement income" for monthly expenses in retirement [1]. For more careful planning, read how much to save for retirement, which explains why such rules of thumb are only a starting point.
What's the bottom line?
A retirement projection is only as good as its assumptions, and this one uses deliberately simple ones: a steady return, steady inflation and a flat contribution. Its value is in comparison — starting earlier, saving more, or assuming lower returns — and in translating a large future number into today's dollars. Read the 401(k) guide and the compound interest calculator next.
Frequently asked questions
Why show today's dollars at all?
A balance decades from now is measured in dollars that will buy less. Dividing by inflation turns it into something you can compare with today's prices and income.
What inflation rate should I enter?
There is no correct number. Many people try a few rates to see the range. Past US inflation is published by the Bureau of Labor Statistics, but future inflation is unknown.
Does total contributed include my current savings?
Yes. It is your current savings plus every monthly contribution until retirement age, before any growth.
Is the return compounded monthly or yearly?
Monthly. Each month the balance earns one-twelfth of the annual return, and your contribution is added at the end of the month.
Sources
Grade A = primary source (regulator, government agency, official rulebook or the index provider's own documents). Numbers in brackets in the text point here.
- U.S. Department of Labor — EBSA. Taking the Mystery Out of Retirement Planning (2026). Accessed 2026-10-03.A
- U.S. Bureau of Labor Statistics. Consumer Price Index (2026). Accessed 2026-10-03.A
This page is general education, not personal financial, tax or legal advice. Figures in worked examples are hypothetical and calculated before taxes and fees unless stated. Rules and limits change; check the linked primary sources for the current version. How we check every page.
