Free online Roth IRA calculator

How to use

1. Enter your current age and retirement age.
2. Enter your current Roth IRA balance and planned annual contribution.
3. Set the expected annual return and your estimated tax rate at retirement.
4. Click Calculate Roth IRA to see the tax-free Roth balance, the traditional IRA after-tax comparison, and your Roth advantage.

The formula

Both Roth and traditional balances grow the same way:

balance = (prev_balance + annual_contribution) × (1 + annual_return)

The difference is in the final comparison:

roth_value           = future_balance           (tax-free)
traditional_value    = future_balance × (1 − tax_rate)
roth_advantage       = roth_value − traditional_value

Worked example

Age 30, retiring at 65. Balance: $10,000. Contribution: $7,000/year. Return: 7%. Tax rate: 25%.

• Roth balance at 65: approximately $1.54 million (tax-free)
• Traditional pre-tax balance: same $1.54 million
• Traditional after-tax (25%): approximately $1.16 million
• Roth advantage: approximately $385,000

This gap grows with higher tax rates and longer time horizons.

Notes

• This calculator uses the same growth model for both accounts. Real-world differences include required minimum distributions (RMDs) for traditional IRAs, state tax treatment, and estate planning implications.
• The Roth IRA has no RMDs during the owner’s lifetime, which can allow additional tax-free compounding versus a traditional IRA.
• Roth conversions (moving traditional IRA funds to Roth) are not modeled here.