About the IRA Calculator
A Traditional IRA grows tax-deferred, meaning you don't pay tax on contributions or growth until you withdraw the money in retirement - at which point it's taxed as ordinary income. Our Traditional IRA Calculator projects both the pre-tax balance and what it's actually worth after tax.
How It Works
The calculator compounds your current balance and monthly contributions the same way any growth projection does, then applies your estimated tax rate at withdrawal to show the after-tax value alongside the full pre-tax balance - since the pre-tax number alone overstates what you'll actually get to spend.
Formula & Methodology
A Traditional IRA defers tax rather than eliminating it - contributions typically reduce taxable income today, and growth compounds tax-deferred, but every withdrawal in retirement is taxed as ordinary income. That's why this projection deliberately shows two numbers instead of one: the pre-tax balance (what the account statement would show) and the after-tax balance (what you'd actually be able to spend once withdrawal tax is subtracted), since only the second number reflects real spending power.
Step-by-Step: Calculating It By Hand
- 1Compound the current balance and monthly contributions forward using the expected rate of return, exactly as in any growth projection.
- 2This produces the pre-tax balance at the end of the projection period.
- 3Multiply the pre-tax balance by your assumed withdrawal tax rate to find the tax owed.
- 4Subtract that tax from the pre-tax balance to find the realistic after-tax, spendable value.
Examples
Pre-tax vs after-tax
$10,000 plus $500/month at 7% for 30 years might grow to a large pre-tax balance, but at a 22% withdrawal tax rate, the after-tax spendable amount is meaningfully lower.
Impact of tax rate assumption
The same balance withdrawn at a lower tax bracket in a low-income retirement year keeps significantly more of the balance intact compared to withdrawing at a higher rate.
Advantages
- Shows both pre-tax and realistic after-tax value, unlike simpler projections
- Makes the impact of your assumed withdrawal tax rate concrete
- Useful for direct comparison against a Roth IRA's fully tax-free growth
- Accounts for the tax-deferred nature of Traditional IRA contributions correctly
Common Mistakes
- Comparing a Traditional IRA's pre-tax balance directly to a Roth IRA's balance without adjusting for tax
- Assuming your tax rate in retirement will match your rate today - it's often lower, but not always
- Forgetting required minimum distributions (RMDs) eventually force withdrawals starting at a certain age
- Not accounting for annual contribution limits, which this simplified model doesn't enforce
Edge Cases to Watch For
- Required minimum distributions force withdrawals starting at a specific age, regardless of whether you actually need the income at that point.
- The tax rate applied at withdrawal depends on your total income in that retirement year, which is genuinely uncertain decades in advance - this projection uses a single assumed rate as an approximation.
- Contributions to a Traditional IRA may not be fully tax-deductible if you (or a spouse) are covered by a workplace retirement plan and income exceeds certain thresholds.
- Withdrawing before age 59½ typically triggers both ordinary income tax and an additional 10% early withdrawal penalty, neither of which this standard retirement-age projection reflects.
Common Use Cases
- Projecting Traditional IRA growth on both a pre-tax and after-tax basis
- Comparing Traditional versus Roth IRA outcomes for your tax situation
- Estimating real retirement spending power, not just account balance
- Planning contribution levels to reach an after-tax retirement goal