Retirement Calculator (401k)
Project how much your retirement savings could grow with regular contributions and compounding.
How to use
- Enter your current and retirement ages.
- Add your current savings, monthly contribution and expected return.
- See your projected nest egg and how much is growth vs contributions.
How the Retirement Calculator (401k) works
Projects a 401(k) or similar retirement balance from your current age to your target retirement age, separating what you contribute from what growth adds.
It compounds month by month from today until retirement: the existing balance grows at the monthly rate, then your monthly contribution is added. The result is split into total contributions and total investment growth.
months = (retirement age − current age) × 12, then balance = balance × (1 + r) + monthly
Worked example
At 30 with $50,000 saved, contributing $1,000 a month at 7% until 65, the balance lands near $1.9 million — of which about $470,000 is contributions and the rest is growth.
Things worth knowing
- Employer matching is free money and is not modelled here; add it to your monthly contribution figure.
- The projection is in nominal dollars. Adjust for inflation before judging whether the number is enough.
- A frequently cited guideline is the 4% rule: an annual withdrawal of about 4% of the balance has historically been sustainable over a 30-year retirement. It is a rough starting point, not a guarantee.
Frequently asked questions
Is the return guaranteed?
No — markets vary year to year. This uses a constant average rate as an estimate.
Should I include employer match?
Yes — add any employer 401k match into your monthly contribution figure.
How much should I be contributing?
Many planners suggest 15% of gross income including any employer match. Starting lower and increasing with each raise works better than waiting until you can afford the full amount.
What return should I assume?
Long-run US equity returns have averaged roughly 10% nominal before inflation, but 6–7% is the more conservative planning figure once inflation and fees are considered.