What Is the 401k vs Roth IRA Calculator?
A 401k vs Roth IRA calculator compares the after-tax outcome of contributing to a traditional pre-tax account versus a Roth after-tax account. The decision hinges on whether your tax rate is higher now or in retirement.
How to use this calculator
Type your numbers into the fields above. The results change the moment you edit any input, so you can try one scenario after another and see exactly what moves. Most calculators show a short summary of the key figures, a line-by-line breakdown underneath, and — where it applies — a year-by-year schedule you can export to a spreadsheet. Everything runs in your browser; nothing is stored or sent anywhere. Treat the output as a planning estimate, not as final word on a real decision.
The Formula
Traditional: contributions are pre-tax, grow tax-deferred, and are taxed at your retirement rate. Roth: contributions are taxed now, grow tax-free, and withdrawals are tax-free. The calculator projects each to an after-tax value using your two tax rates.
Worked Example
Contributing $6,000 a year for 30 years at 7% with a 22% tax rate now and 15% in retirement favors the Roth, because paying 22% now beats paying 15% later on a larger balance — though the gap depends on the rates you enter.
Tips for the Most Accurate Estimate
- Expect a lower rate later? Traditional may win.
- Expect a higher rate later? Roth may win.
- Diversify with both types if eligible for flexibility.
- Employer matches are always traditional.
- Younger savers often benefit more from Roth.
Frequently Asked Questions
Q: When does Roth beat traditional?
When your tax rate in retirement is higher than today's, because Roth locks in the lower current rate and shields all growth.
Q: Are withdrawals really tax-free with Roth?
Qualified Roth withdrawals are tax-free, since contributions were made with after-tax dollars and growth is exempt.
Q: Can I have both?
Often yes, within contribution limits. Many people use both for tax diversification in retirement.