Roth 401k Calculator
After-tax contributions in, tax-free retirement income out — modeled against Traditional 401k at your brackets.
Estimate your Roth 401(k) balance at retirement using compound growth on after-tax contributions, and compare your tax-free outcome against a Traditional 401(k) to see which strategy wins for your tax situation.
The only number a Roth 401k calculator can’t give you is whether Roth or Traditional wins for your situation — that depends on whether your tax rate is higher now or in retirement. Everything else it handles: projected balance, after-tax value at withdrawal, and how employer match interacts with each contribution type. Enter your salary, contribution rate, expected return, and both tax brackets, and the calculator shows the spendable outcome at retirement — not just the raw account balance.
Roth 401k Contribution Limits in 2026
Roth and Traditional 401k share the same IRS employee deferral limits. For 2026:
| Age | Contribution Limit | Total Limit (Employee + Employer) |
|---|---|---|
| Under 50 | $24,500 | $70,000 |
| 50–59 and 64+ | $32,500 (includes $8,000 catch-up) | $77,500 |
| 60–63 (SECURE 2.0 super catch-up) | $35,750 | $80,750 |
Roth 401k vs Traditional 401k: Which Comes Out Ahead?
With identical contribution amounts and identical returns, the math is straightforward: Roth wins if your retirement tax rate is higher than your current rate; Traditional wins if it’s lower. The complication is that most people misjudge their retirement tax bracket. Social Security benefits are partially taxable, Required Minimum Distributions from Traditional accounts force taxable income whether you need it or not, and many retirees end up in a higher bracket than expected once all income sources are combined.
| Scenario | Current Bracket | Retirement Bracket | Winner |
|---|---|---|---|
| Early career, low income | 12% | 22% | Roth — by a large margin |
| Mid-career, moderate income | 22% | 22% | Tie — tax diversification preferred |
| Peak earner, high income | 32% | 22% | Traditional — defer taxes until lower bracket |
| Any age, expecting tax increases | Any | Higher | Roth — lock in today’s rates |
A 28-year-old in the 12% bracket today is very likely a 22% retiree after factoring in Social Security and RMDs — Roth wins decisively. A 55-year-old at peak income in the 32% bracket who expects to spend less in retirement should lean Traditional now. The calculator above models both scenarios with your actual numbers.
Does Employer Match Go Into Roth or Traditional?
Always Traditional, regardless of what you elect. By law, employer matching contributions are pre-tax and go into the Traditional side of the account. Your Roth 401k account effectively has two buckets: your after-tax contributions (and their growth) which come out tax-free, and the employer match (and its growth) which is taxed as ordinary income when withdrawn. The calculator models both buckets separately so the after-tax retirement income number is accurate — not just the total balance.
Roth 401k Withdrawal Rules and the 5-Year Rule
Qualified withdrawals from a Roth 401k are tax and penalty-free after age 59½ — but only if the account has been open for at least five years. This 5-year clock starts January 1 of the first year you made a Roth 401k contribution. Someone who opens a Roth 401k at 57 can’t take tax-free withdrawals at 59½ — they have to wait until 62 when the 5-year requirement is met.
Early withdrawals before 59½ are more complicated than a Roth IRA. Unlike a Roth IRA where contributions can be withdrawn anytime penalty-free, a Roth 401k treats every withdrawal as a pro-rata mix of contributions and earnings. If your account is 75% contributions and 25% earnings, a $10,000 withdrawal at age 50 means $2,500 is treated as earnings — subject to income tax and the 10% early withdrawal penalty.
Roth 401k RMDs: What Changed Under SECURE 2.0
Before SECURE 2.0, Roth 401k accounts were subject to Required Minimum Distributions at age 73 — one of the few disadvantages versus a Roth IRA. SECURE 2.0 eliminated RMDs for Roth 401k accounts entirely starting in 2024. You can now leave the money in the account indefinitely, let it compound tax-free, and pass it to heirs without being forced into distributions. This makes the Roth 401k significantly more attractive for estate planning and for anyone who doesn’t need the money in retirement but wants tax-free growth to continue.
Mega Backdoor Roth: Contribution Space Beyond $24,500
High earners whose plan allows after-tax (non-Roth) contributions and in-plan Roth conversions can contribute far beyond the $24,500 employee deferral limit. The 2026 total §415(c) limit is $70,000 per person. Subtract your $24,500 deferral and any employer match — the remaining space can be filled with after-tax contributions, then immediately converted to Roth inside the plan. In practice: a $200,000 salary earner with a 4% employer match ($8,000) has $37,500 of remaining after-tax contribution space. Converted to Roth, that’s $62,000 of total Roth-destined contributions in a single year — 2.5× the standard limit. Most large employer plans permit this; many small employer plans don’t. Check your Summary Plan Description for “after-tax contributions” and “in-plan Roth conversions.”
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$24,500 for employees under 50, $32,500 for ages 50–59 and 64+ (includes $8,000 catch-up), and $35,750 for ages 60–63 under SECURE 2.0's super catch-up. These limits are shared with Traditional 401k — you can't contribute $24,500 to each. The combined employer + employee total limit is $70,000 for under-50 workers, up to $80,750 for the 60–63 age group.
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Roth wins if your retirement tax rate will be higher than today's. Traditional wins if it will be lower. Most workers in the 12–22% bracket — especially younger ones — benefit from Roth because Social Security taxability and RMDs from pre-tax accounts often push retirement income into a higher bracket than expected. Peak earners at 32%+ who expect to spend significantly less in retirement generally benefit from Traditional now.
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No — SECURE 2.0, effective 2024, eliminated RMDs for Roth 401k accounts. Previously required at age 73, that rule no longer applies. Roth 401k balances can now compound tax-free indefinitely with no forced distributions, making them significantly more attractive for estate planning compared to Traditional accounts.
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Yes — they're separate accounts with separate limits. The Roth 401k limit is $24,500 in 2026 (under 50); the Roth IRA limit is $7,500. The two don't affect each other. The only Roth IRA restriction is income — single filers phase out at $153,000–$168,000 MAGI, married filers at $242,000–$252,000. Above those limits you can still contribute to a Roth 401k (no income limit applies) but not directly to a Roth IRA.