How we calculate

Four rules we follow

• Official figures only. Every rate, threshold and table comes from the IRS, the Social Security Administration or Medicare, and the page that uses it names the source.
• Exact money. Amounts are kept in whole cents and rounded only for display.
• Tested examples. The worked examples on each calculator and on this page are checked by automated tests that run on every change.
• Updated when the agencies publish. The IRS sets next year’s tax brackets each fall, and Medicare announces premiums around November. Each page shows when it was last updated.

This page covers the free calculators. The full planner uses its own projection engine.

RMD calculator

1. The start age comes from your birth year under SECURE 2.0: 73 if you were born from 1951 to 1959, and 75 if you were born in 1960 or later.
2. Each year’s RMD is the balance on December 31 of the year before, divided by the Uniform Lifetime Table factor for the age you reach that year, rounded down to the cent.
3. For later years, the balance left after each RMD grows at the rate you enter, with nothing else added or taken out.

Example: turning 75 in 2026 with $500,000.00 gives $500,000.00 ÷ 24.6 = $20,325.20.

Not covered: the smaller RMDs when a spouse more than 10 years younger is the only beneficiary, inherited accounts, and the still-working exception for a current employer’s plan.

Social Security calculator

1. Full retirement age comes from the year of birth, using Social Security’s table: 66 for 1943 to 1954, rising by 2 months a year to 67 for 1960 or later. Someone born on January 1 uses the previous year.
2. The benefit at each claim age from 62 to 70 is the benefit at full retirement age (the primary insurance amount) less 5/9 of 1% for each of the first 36 months before full retirement age and 5/12 of 1% for each month before that, or plus 2/3 of 1% for each month after it, up to 70. Monthly amounts are rounded down to the dollar, as Social Security pays them.
3. Each total is the monthly benefit times the months from the claim age until the plan-to age. The break-even age, rounded up to the month, is when a later claim has paid as much in total as an earlier one.
4. A spouse’s benefit is their own benefit plus, if half of the worker’s full benefit is more than their own full benefit, the difference, reduced by 25/36 of 1% a month for the first 36 months before their full retirement age and 5/12 of 1% a month before that. It assumes the worker has already filed.
5. The survivor benefit assumes the survivor has reached full retirement age for survivor benefits. It is the worker’s benefit including delayed credits, or, if the worker claimed early, the larger of that reduced benefit and 82.5% of the full benefit.

Every amount is in today’s dollars. Benefits rise each January with the cost-of-living adjustment, so in today’s dollars they stay level for life, and no inflation rate is needed.

Example: born in 1960 with $2,000 a month at full retirement age, the benefit is $1,400 at 62 and $2,480 at 70. Planning to 90, claiming at 70 collects the most: $595,200.

Not covered: the earnings test for people who claim early and keep working, the family maximum, income tax on benefits, and Medicare premiums taken out of them. A pension from work that didn’t pay Social Security tax no longer reduces benefits: the Social Security Fairness Act, signed in January 2025, ended the Windfall Elimination Provision and the Government Pension Offset.

Roth conversion tax calculator

The calculator works out 2026 federal income tax twice, without and with the conversion, for single and married-filing-jointly returns. Each time it:

1. Adds up your other income and the conversion, then works out the taxable part of Social Security line by line as IRS Publication 915’s worksheet does. Benefits start to be taxed when other income plus half of benefits passes $25,000 ($32,000 joint), and at most 85% of them can be.
2. Subtracts the standard deduction, including the extra amount for each filer 65 or older, and the senior deduction: $6,000 per person 65 or older, reduced by 6% of modified adjusted gross income over $75,000 ($150,000 joint) for each person.
3. Applies the 2026 brackets to what’s left.

The tax on the conversion is the difference between the two results. “Room left in the bracket” is found by search rather than subtraction, because a converted dollar can add more than a dollar of taxable income while Social Security becomes taxable or the senior deduction shrinks.

For Medicare, it compares your 2026 modified adjusted gross income with and without the conversion against the 2026 IRMAA thresholds, for anyone 63 or older who will be on Medicare in 2028. The 2028 thresholds aren’t published yet and will likely be higher.

Example: a married couple, both 67, with $48,000 of Social Security and $60,000 of other income, converting $40,000, owe $10,700 instead of $5,804: $4,896 on the conversion.

IRMAA calculator

1. Modified adjusted gross income is adjusted gross income plus tax-exempt interest, from the tax return 2 years before the premium year.
2. Your tier is the first one whose upper limit is at or above that income. The standard tier ends at $109,000 for single filers and $218,000 for joint filers; married people who file separately have three tiers of their own.
3. The yearly extra cost is 12 times the Part B and Part D monthly surcharges, per person on Medicare.

What the calculators leave out

• State and local income taxes.
• Capital gains, qualified dividends and the net investment income tax.
• Itemized deductions and credits.
• The IRS tax table: below $100,000 of taxable income, returns look up tax in steps of up to $50 instead of using the exact formula, so a real return can differ by a few dollars.
• Future years: tax figures are for 2026, and Medicare figures for 2026.

The calculators do arithmetic, not advice. Check important decisions with a qualified professional.

Found a mistake?

Email admin@quantlance.com with the page, what you entered, and what you expected. Confirmed errors are fixed, and the date at the bottom of the page changes.

Free, and funded by donations

The calculators and the planner cost nothing and show no ads. Velafolio is supported by donations.