The formula for a Required Minimum Distribution (RMD) is straightforward:
RMD = Prior year-end account balance ÷ IRS life expectancy factor
The life expectancy factor comes from the IRS Uniform Lifetime Table, based on the age you’ll be at the end of the distribution year. Here’s what that looks like with real numbers.
In short: Take your December 31 account balance, divide by the IRS factor for your age, and that’s your RMD. The SimpleRMD calculator does this automatically across multiple accounts — free, no signup.
A Single-Account Example
Situation: David is 75 years old and has one Traditional IRA. His account balance on December 31 of the prior year was $320,000.
Step 1: Find the IRS life expectancy factor.
David looks up age 75 in the IRS Uniform Lifetime Table (IRS Publication 590-B). The factor is 24.6.
Step 2: Divide.
| Input | Value |
|---|---|
| Prior year-end balance | $320,000 |
| IRS factor (age 75) | 24.6 |
| RMD | $13,008 |
$320,000 ÷ 24.6 = $13,008.13 — rounded to the nearest dollar.
David must withdraw at least $13,008 from his IRA by December 31.
A Two-Account Example
Most people have more than one IRA. The math is the same — you just do it twice, then add.
Situation: Same David, same year — but he also has a Rollover IRA with a prior year-end balance of $85,000.
| Account | Balance | IRS Factor (age 75) | RMD |
|---|---|---|---|
| Traditional IRA | $320,000 | 24.6 | $13,008 |
| Rollover IRA | $85,000 | 24.6 | $3,455 |
| Total | $405,000 | $16,463 |
David’s total RMD is $16,463. Because both accounts are IRA-type accounts, he can take the full amount from either one — or split it however he chooses. He doesn’t have to take a separate distribution from each account.
Important: This flexibility applies to Traditional, Rollover, SEP, and SIMPLE IRAs. It does not apply to 401(k)s — each 401(k) must satisfy its own RMD separately. See aggregation rules →
What Changes the Factor
The IRS life expectancy factor decreases by roughly one point each year as you age — which means your RMD percentage gradually increases over time.
| Age | IRS Factor | RMD % of Balance |
|---|---|---|
| 73 | 26.5 | 3.77% |
| 75 | 24.6 | 4.07% |
| 80 | 20.2 | 4.95% |
| 85 | 16.0 | 6.25% |
| 90 | 12.2 | 8.20% |
One exception: if your sole beneficiary is a spouse more than 10 years younger, you use the Joint Life Table instead — which produces a lower factor and a smaller RMD. See RMD tables explained →
Ready to Run Your Own Numbers?
The calculator does this math for you — across as many accounts as you have, with the correct table applied automatically.
Run the RMD calculator → — free, no account required
Related
- RMD table explained → — where the factors come from
- Is this calculator accurate? → — how we verify the math
- How to calculate your RMD → — deeper walkthrough
- What information do I need? →
This page is for informational purposes only and does not constitute tax, legal, or financial advice. IRS rules are subject to change. Consult a qualified tax professional for guidance specific to your situation. Rules confirmed current as of April 2026 per IRS Publication 590-B (2025).