About Retire By When

Retire By When is eight retirement calculators built around one idea: show the formula, not just the number. Every tool states the math it runs, works a real example through to the penny, and cites the IRS figure or published rule of thumb it relies on -- the current 401(k) contribution limit, the IRS Uniform Lifetime Table for required minimum distributions, the origin of the 4% rule.

How the calculators work

Every growth projection on this site -- 401(k), Roth IRA, traditional IRA, the retirement savings target -- runs through one shared engine that simulates month by month, rather than a single end-of-horizon formula. Where a textbook closed-form formula applies exactly (a flat contribution, a whole number of years), that formula is used as an independent cross-check in the site's own test suite, so the simulation and the textbook math are proven to agree to the cent before anything ships.

Where the IRS figures come from

2026 contribution limits (401(k) elective deferral, IRA contributions, and the age-50 and age-60-63 catch-ups) come from IRS Notice 2025-67. Required minimum distribution divisors come from IRS Publication 590-B, Appendix B, Table III (the Uniform Lifetime Table). Both are linked directly from the pages that use them, not just named. Net worth reference figures come from the Federal Reserve's own Survey of Consumer Finances, labeled clearly as Federal Reserve data rather than this site's own numbers.

What it doesn't do

This isn't financial, tax or legal advice, and Retire By When isn't affiliated with any employer, plan administrator, bank, brokerage or the IRS. Every result is an estimate built from constant-rate, constant-contribution assumptions -- real accounts have fees, variable returns, plan-specific rules and tax situations this tool can't know. See Terms.

Every calculator

• 401(k) Calculator -- Project your 401(k) balance at retirement from salary, contribution rate, employer match and return, with the current IRS elective-deferral limit applied.
• Solo 401(k) Calculator -- Max employee deferral and employer profit-sharing contribution for a self-employed solo 401(k), with the real IRS combined limit -- not a flat 25% guess.
• Roth IRA Calculator -- Roth IRA growth at your contribution, years and return, with the IRS limit and 50+ catch-up shown, compared to a taxable account at your marginal rate.
• Traditional IRA Calculator -- Traditional IRA growth on a deductible contribution, tax-deferred until withdrawal, with the tax bill at your stated withdrawal tax rate shown separately.
• IRA & Roth IRA Contribution Limits (2025 & 2026) -- The real 2025 and 2026 IRA and Roth IRA contribution limits side by side: the combined-limit rule, the 50+ catch-up, and Roth income phase-out ranges by filing status, sourced to the IRS.
• Retirement Savings Calculator -- Check your projected retirement balance against a spending target using the 4% rule or your own rate, with the gap and monthly savings needed to close it.
• Retirement Withdrawal Calculator -- How long a retirement balance lasts at a given withdrawal rate, expected return and inflation, with a year-by-year table showing when it runs out.
• RMD Calculator -- Your required minimum distribution from a traditional IRA or 401(k), using the IRS Uniform Lifetime Table, with a multi-year projection of future RMDs.
• Net Worth Calculator -- Total assets minus liabilities by category, with a Federal Reserve reference table showing median net worth by age so you can see where you stand.
• Budget Calculator -- Split your take-home pay into needs, wants and savings using the 50/30/20 rule or your own percentages, with a monthly table.
• Coast FIRE Calculator -- Find your Coast FIRE number -- what you'd need saved today to reach your retirement target on growth alone, with zero further contributions -- and see the gap to it.
• HYSA Calculator -- Project a high-yield savings account balance from a starting deposit, monthly contributions and APY, compounded the way a real HYSA credits interest.
• Dave Ramsey Investment Calculator -- Project investment growth using Dave Ramsey's commonly cited 12% return assumption, shown side by side with a more conservative, compounded historical rate.
• Annuity Calculator -- Estimate the fixed monthly income a lump sum would pay out over a set period at a guaranteed rate -- a period-certain fixed annuity, not a lifetime, variable or indexed contract.
• CD Rate Calculator -- Calculate a certificate of deposit's maturity value, interest earned and early-withdrawal penalty from your deposit, APY and term length.
• Capital Gains Tax Calculator -- Estimate federal long-term capital gains tax on an investment sale using the real 2026 IRS income brackets, stacked on top of your other taxable income.

About the builder

Every closed-form textbook formula that applies on Retire By When -- a flat contribution, a whole number of years -- is kept in the test suite as an independent check the month-by-month simulation engine has to match to the cent. Elbert Ballo built and maintains the site.

Corrections

If a formula, IRS figure or citation here is wrong or out of date, email hello@retirebywhen.com.