The 4% rule is a rough guideline that says you can withdraw about 4% of your retirement portfolio in the first year, then adjust that dollar amount for inflation, with a good chance the money lasts 30 years. This calculator uses your chosen withdrawal rate to estimate monthly retirement income.

Retirement & 401(k) Calculator

Q: How much should I contribute to my 401(k)?

At an absolute minimum, contribute enough to capture your full employer match — that is an immediate 50-100% return. A widely used rule of thumb is to save about 15% of your gross income for retirement, including the employer match, increasing the rate over time as your income grows.



Adjust the inputs above to see the breakdown.

How to Use This Calculator

Enter your current age and target retirement age — the gap between them is your investing runway.
Enter your current retirement balance and annual salary.
Set your contribution rate (a percentage of salary) and your employer match.
Choose an expected annual return and an annual raise so future contributions grow with your income.
Read the projection. You get the projected balance at retirement, how much you contributed, how much is investment growth, and an estimate of monthly income using your chosen safe-withdrawal rate. The chart plots the balance year by year against your total contributions.

The Formula Explained

The model steps forward one month at a time. Each month the balance earns one-twelfth of the expected annual return, then a contribution is added:

balanceₙₑw = balanceₒₗd × (1 + r ÷ 12) + (salary ÷ 12) × (c + m)

r — expected annual return
c — your contribution rate (as a decimal)
m — employer match rate (as a decimal)

Once a year the salary is multiplied by (1 + raise) so contributions keep pace with your income. Estimated monthly retirement income is final balance × withdrawal rate ÷ 12 — the withdrawal-rate box defaults to the 4% rule.

Frequently Asked Questions

How much should I contribute to my 401(k)?

At a minimum, contribute enough to capture your full employer match — that is an immediate 50–100% return on those dollars. A widely used target is to save about 15% of gross income for retirement including the match, raising the percentage as your salary grows.

What rate of return should I assume?

A diversified stock-and-bond portfolio has historically returned roughly 6–7% per year after inflation over multi-decade periods. Single-year returns swing far more than that, so treat the projection as a planning estimate and revisit it every year or two.

What is the 4% rule?

It is a rough guideline: withdraw about 4% of your portfolio in your first year of retirement, then adjust that dollar figure for inflation each year, and the money has historically had a good chance of lasting 30 years. Lower the withdrawal-rate input for a more cautious plan.

Related Calculators

Compound Interest — the growth engine behind this projection, in isolation.
Inflation Calculator — what your future balance is worth in today's dollars.
Rule of 72 — a fast estimate of how many times your savings will double before you retire.